1 40 381 https://bereket-haileab.geology.sites.carleton.edu/files/original/41ec0f21db4110d9e1987bae5b5d5d25.jpg 149ef59718886f0eb494742a7fccc4ad https://bereket-haileab.geology.sites.carleton.edu/files/original/a138dad2b3de053078b64679e993b202.jpg a08d4392a96c3fe87933a550f972ddb4 https://bereket-haileab.geology.sites.carleton.edu/files/original/1e807aaea88a8858a029d78eed18ac5b.jpg 8e4129855668635c94aaa61538bcdd5a Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Sedimentary Rocks Subject The topic of the resource This collection includes sandstones, limestones, breccias, conglomerates, dolostones, shales, oolites, and BIF. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-143a Subject The topic of the resource Mill Street Conglomerate Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Taylors Falls Minnesota GPS Coordinates: 45°23'53.03"N 92°39'34.41"W Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample BH250-143a. Housed at Carleton College in Minnesota. Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1Hwu8K_pCgPGAsXSohYImJTFsKWp0dSgT/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1Q7VBNXH5S6xO552if3ILSBq_7wI1biSf/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1f1w8VBzRVW2EAgavPuhQ0Efa6Q2WB_Sy/preview" allow="autoplay"></iframe> Description An account of the resource Mill Street Conglomerate Geologic significance: Great Unconformity The Mill Street Conglomerate is a coarse, clast-supported sedimentary rock exposed near Taylors Falls. It consists predominantly of subrounded to well-rounded basalt cobbles and smaller basalt fragments. The spaces between the larger clasts are filled with granule- to sand-sized basalt debris and finer sediment. The poor sorting and coarse grain size indicate deposition in a high-energy environment capable of transporting and reworking cobbles and boulders. The basalt clasts were eroded from the much older volcanic rocks of the Midcontinent Rift. Their rounded shapes record repeated abrasion, probably along a Cambrian shoreline as waves reworked the exposed basalt landscape. Variations in clast size and matrix abundance reflect changing water energy and local relief along that ancient coast. At Taylors Falls, the conglomerate rests unconformably on approximately 1.1-billion-year-old basalt. This contact is part of the Great Unconformity and represents hundreds of millions of years of weathering, erosion, and missing geologic time before younger sediment accumulated. BH250-143a therefore preserves both the erosion of the ancient volcanic landscape and the return of sedimentation during the Paleozoic. basalt clasts Cambrian shoreline clast-supported conglomerate Great Unconformity high-energy environment Midcontinent Rift Mill Street Minnesota geology nonconformity poorly sorted rounded cobbles Taylors Falls https://bereket-haileab.geology.sites.carleton.edu/files/original/cc7fa07caad5568a28237e69d9ef4db8.jpg 0301a9b0b4bd7dedf6761a05b9ae7594 https://bereket-haileab.geology.sites.carleton.edu/files/original/323e6a0b7521d85951abbcc30c3d6ac6.jpg 1933f4e4457ae09d46003679f7969865 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Sedimentary Rocks Subject The topic of the resource This collection includes sandstones, limestones, breccias, conglomerates, dolostones, shales, oolites, and BIF. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-128h Subject The topic of the resource Galena Limestone Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Near Sogn on Highway 14 GPS coordinates: 44°21'54.57"N, 92°56'1.14"W Creator An entity primarily responsible for making the resource Bereket Haileab Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1WygzFS-F2D1R8AnzJaoExa00qO_SQh1D/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/14xK_7YwrLI_ZgErYcQSolWHYheyXRAzR/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1sArahiF5g3vpQ3ziNsmQBGbAhQxHal92/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1ZjMAVdlGe32kpnSTznGZDVx1a-OZZu14/preview" allow="autoplay"></iframe> Type The nature or genre of the resource Hand sample Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample BH250-128h. Housed at Carleton College in Minnesota. Description An account of the resource BH250-128h is a fossiliferous sample of Galena Limestone collected near Sogn in Goodhue County, southeastern Minnesota. The limestone contains abundant evidence of marine life, including rugose corals and numerous burrows produced by organisms living within or moving through the seafloor sediment. These fossils and trace fossils indicate deposition in a shallow marine environment with an active benthic community. The sample preserves both skeletal material and bioturbation, making it useful for studying the marine environments represented by the Galena Limestone. bioturbation burrows Carbonate rock coral fossil Fossiliferous Limestone Galena Group Galena Limestone Goodhue County limestone Rugose coral Sedimentary rock Sogn southeastern Minnesota Trace fossils https://bereket-haileab.geology.sites.carleton.edu/files/original/760dc50aa171f1b7216930e6c2095d63.jpg 44c83b3f700c5241a82bc440c2026d75 https://bereket-haileab.geology.sites.carleton.edu/files/original/58b358c783e01994b774ee519b2549cc.jpg 52c22b2830b9902c49b2cb0f0b875ac0 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Sedimentary Rocks Subject The topic of the resource This collection includes sandstones, limestones, breccias, conglomerates, dolostones, shales, oolites, and BIF. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-128g Subject The topic of the resource Glen Wood Shale Description An account of the resource Glen Wood Shale BH250-128g is a sample of the Glenwood Formation collected in the Sogn Valley along Highway 14 in southeastern Minnesota. At this locality, the formation is concealed beneath soil and vegetation, so it is necessary to dig into the roadside ditch to expose the outcrop. The rock is a soft, fissile, greenish-gray shale composed primarily of clay minerals with minor silt-sized quartz and other detrital grains. It was deposited during the Middle Ordovician in a quiet, shallow-marine environment as rising sea level flooded the sandy seafloor represented by the underlying St. Peter Sandstone. The Glenwood Formation is overlain by carbonate rocks of the Platteville Formation. Although relatively thin, the Glenwood Shale is environmentally and hydrogeologically important. Its low permeability restricts groundwater movement between the permeable St. Peter Sandstone and the overlying carbonate rocks. Water commonly moves laterally along the sandstone–shale contact, producing seeps, springs, and wet zones where the contact intersects the land surface. Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Sogn Valley, Goodhue County Creator An entity primarily responsible for making the resource Bereket Haileab Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1LeA00LKFCGjDh2L5AWuxC55ElsWp1IuQ/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/11mDQ_kogiqtayqkaWFMyFSEcxV1wr19l/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1HeQnhf-uAd-lnuOvB428BNRDDjqhNgvE/preview" allow="autoplay"></iframe> Glenwood Formation Glenwood Shale Middle Ordovician Platteville Formation Sedimentary rock shale southeastern Minnesota St. Peter Sandstone https://bereket-haileab.geology.sites.carleton.edu/files/original/ab7164c326ff266111ffa0049e509219.jpg ad0229fc4bd699d4cdef0e6049ff096f https://bereket-haileab.geology.sites.carleton.edu/files/original/03e7efbff5e2dd17c3e565d880b005d9.jpg 7c9fe3514d295c68e4a0641f0e3730c3 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Sedimentary Rocks Subject The topic of the resource This collection includes sandstones, limestones, breccias, conglomerates, dolostones, shales, oolites, and BIF. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-128e Subject The topic of the resource Shakopee Dolostone (Upper part of the Prairie du Chien Group) Description An account of the resource Major Minerals: Quartz, dolomite BH250-128e is a sample of the Shakopee Dolostone collected from the Cannon River Wilderness Park area in Rice County, Minnesota. The Shakopee Dolostone forms the upper part of the Lower Ordovician Prairie du Chien Group and consists primarily of dolostone interbedded with varying amounts of sandstone, siltstone, shale, and chert. The Shakopee Dolostone overlies the Oneota Dolostone and records deposition in a warm, shallow-marine carbonate environment. Sandy and silty intervals indicate periodic influxes of siliciclastic sediment into the carbonate system. Later dolomitization altered much of the original limestone and may have obscured some primary sedimentary textures. Some exposures preserve stromatolites and other laminated structures formed by microbial mats. These features provide evidence of biological activity in shallow, commonly restricted marine environments during the Early Ordovician. Near the site where BH250-128e was collected, groundwater emerges as springs along or near the contact between the Shakopee Dolostone and the overlying St. Peter Sandstone. These springs support microbial communities associated with the oxidation of dissolved ferrous iron (Fe²⁺) to ferric iron (Fe³⁺). The resulting iron oxyhydroxide minerals form conspicuous reddish-orange coatings on the exposed Shakopee Dolostone. This modern process illustrates the close relationship among groundwater flow, microorganisms, oxidation–reduction reactions, and mineral precipitation. Related sample: BH250-128b — Oneota Dolostone Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Cannon River Wilderness Park GPS coordinates: 44°23'11.15"N, 93°12'4.06"W Creator An entity primarily responsible for making the resource Bereket Haileab Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1kzcVbW3dVORosRzUG6jCeoZJ6U_D3lFy/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1SprYyka_lmbrSOFgiOuTot3pNtw13ptn/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1yNlvhlR9gPDF0tIuDMjYjcfHoJAG4s2l/preview" allow="autoplay"></iframe> Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample BH250-128e. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section and hand sample Cannon River Wilderness Park carbonate platform Carbonate rock Dolomitization dolostone Early Ordovician ferric iron ferrous iron geomicrobiology groundwater discharge iron oxidation iron oxyhydroxide iron-rich groundwater Lower Ordovician microbial community microbial mat mineral precipitation Minnesota Prairie du Chien Group reddish-orange coating redox reactions Rice County sandstone Sedimentary rock Shakopee Dolostone Shakopee Formation shale shallow-marine environment siliciclastic sediment siltstone spring St. Peter Sandstone stratigraphic contact stromatolite https://bereket-haileab.geology.sites.carleton.edu/files/original/30662e40af59e7c353178e81a775d7b6.jpg dad97add8bf9f1d8837c5a5ae221f2e1 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-256 Subject The topic of the resource Spherulitic or accretionary-lapilli-bearing rhyolitic tuff Description An account of the resource BH250-256 is a reddish-purple, fine-grained rhyolitic volcanic rock from Missouri, tentatively identified as an ignimbrite or tuff. It contains abundant rounded, millimeter-scale structures concentrated in distinct bands. These features may be accretionary lapilli formed from fine ash within an eruption cloud, or spherulites produced by the crystallization of volcanic glass during cooling. Similar features occur in Mesoproterozoic volcanic rocks of the St. Francois Mountains, including the Johnson Shut-Ins Rhyolite. This identification is provisional and will be evaluated through thin-section examination Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Missouri Creator An entity primarily responsible for making the resource Bereket Haileab Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1PRYTi9mPwTke7V_pw0zmqFpCVPvf4VLn/preview" allow="autoplay"></iframe> Accretionary lapilli ash-flow deposit devitrification Felsic Volcanic Rock ignimbrite Johnson Shut-Ins Rhyolite Missouri pyroclastic rock rhyolite rhyolitic tuff spherulites St. Francois Mountains Volcanic glass welded tuff https://bereket-haileab.geology.sites.carleton.edu/files/original/7b01c9b2ae26743fcf0ce20f7bc33f6b.jpg 2e7ee381de3294f9398c564138ac9340 https://bereket-haileab.geology.sites.carleton.edu/files/original/47a600c8754b1b4311a3f13d961cbb86.jpg acf497ecc3e8d0dba30339bf092f31df Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-255 Subject The topic of the resource Basalt BH250-255 consists of basalt samples from the Oligocene–Miocene Ancud Volcanic Complex in Chile. The samples were collected during fall 2024 by Annie Jay, Carleton College Class of 2026, at approximately 41°52′1.20″S, 74°00′55.32″W. Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Chile GPS: coordinates, 41°52'1.20"S, 74° 0'55.32"W Date A point or period of time associated with an event in the lifecycle of the resource Fall 2025 Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Chile Contributor An entity responsible for making contributions to the resource Annie Jay Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1neVWUeUO1IU774FRuYqlPVWxfVmtidV2/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1d7K4LgjNTw_z9KOri1vnIIRazSi8u5bL/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1jLt0sMO9TZAtKtk3fK_MFKh6RJbhrfAd/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1TqjKHWF-4NA-Iz9Xli9soRrEJ04_lSbA/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1bfMdBIHEmBsJiCAO79h9gbtasuJTRkHh/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1rq5tPlLTJ4Pinr-yRA2J97Uz5CMCykd5/preview" allow="autoplay"></iframe> Ancud Volcanic Complex basalt Cenozoic Chile columnar joint mafic rock Miocene Oligocene South America Volcanic rock https://bereket-haileab.geology.sites.carleton.edu/files/original/be15f974c5f99d07fe992882a69b55da.jpg 1d83c5463b645ca996726a6076ccca5c Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-254b Subject The topic of the resource Lithographic limestone Description An account of the resource This specimen is a lithographic limestone obtained from the Carleton College Printmaking Studio. Its original formation and quarry are not documented, but it is hypothesized to be Solnhofen Plattenkalk from Bavaria, Germany, possibly from the quarry area near 48°52′59.2″N, 10°59′42.7″E. This identification should remain provisional until collection records or analytical evidence confirm its provenance. Major minerals: Calcite Creator An entity primarily responsible for making the resource Bereket Haileab Contributor An entity responsible for making contributions to the resource Chloe Fandel Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Unknown, hypothesized to be Jurassic Solnhofen Plattenkalk Source: Carleton Printmaking Studio Solnhofen Quarry, Bavaria, Germany GPS coordinates: 48°52'59.2"N 10°59'42.7"E Date A point or period of time associated with an event in the lifecycle of the resource Summer 2026 Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/19Ru9JLCecbo_evHxR6L0h8ku-h9MXDtb/preview" allow="autoplay"></iframe> Altmühltal Formation Bavaria Calcite Carbonate rock fine-grained limestone Germany laminated limestone limestone Lithographic limestone lithography Micrite Micritic limestone printing stone printmaking Sedimentary rock Solnhofen Limestone Solnhofen Plattenkalk https://bereket-haileab.geology.sites.carleton.edu/files/original/c73993bb374abaa679378f630c8d70d8.jpg f38c67075aef64124625f1f7eb928f72 https://bereket-haileab.geology.sites.carleton.edu/files/original/a37cc9885d113cf438a1acf5ea765824.jpg d4ac6993250d2f8860a79732fe055b55 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Sedimentary Rocks Subject The topic of the resource This collection includes sandstones, limestones, breccias, conglomerates, dolostones, shales, oolites, and BIF. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-254a Subject The topic of the resource Lithographic limestone Description An account of the resource Calicte Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Jones Pit, Orchard, Iowa, USA GPS coordinates: 43°11'38.2"N 92°48'59.5"W Date A point or period of time associated with an event in the lifecycle of the resource Collected: Summer 2026 Creator An entity primarily responsible for making the resource Bereket Haileab Contributor An entity responsible for making contributions to the resource Chloe Fandel Type The nature or genre of the resource Hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/127Z8knW3yWo7g88Zi5H_lQpYkpNm7-CU/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1EVK-jMJNCNdiWjULBrq-aqpGWUemjAsf/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1dKB5rvsvDVDst5JEWmEcyb_pKEqM47SE/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1sZDKu1MDgBGEFCrdTjUu32_UiDZdSwr0/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1f1nJY-5pnC-kgZP2wExcX4CH2Ns3tPGA/preview" allow="autoplay"></iframe> Carbonate rock Cedar Valley Group conchoiial fracture Idlewild Member Iowa Jones Pit laminated limestone limestone Lithograph City Formation Lithographic limestone lithography Micrite printing stone Sedimentary rock https://bereket-haileab.geology.sites.carleton.edu/files/original/5df97fd2ae4cf1624cdbd708345174bc.jpg 34c56b5bb52b264b8dfb9fe4f7b06973 https://bereket-haileab.geology.sites.carleton.edu/files/original/df8c96bc0dae46d4c249147f76178936.jpg 83f4ceb412f477d7c95f5586c4da6e0e Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Metamorphic Rocks Subject The topic of the resource This collection includes slates, phyllites, schists, gneisses, eclogites, marbles, quartzites, skarns, granulites, and mylonites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-37c Subject The topic of the resource Blue Calcite Description An account of the resource BH250-37c is a blue calcite from the Crestmore Quarry district of Riverside County, California. The specimen consists predominantly of coarse crystalline calcite exhibiting excellent rhombohedral cleavage, vitreous luster, and the characteristic pale- to deep-blue coloration for which Crestmore is renowned. The Crestmore deposit formed within magnesium-rich limestone that was subjected to intense contact metamorphism during intrusion of granodioritic and related magmas. Heat and chemically active fluids recrystallized the original limestone into marble and produced one of the most mineralogically diverse skarn localities in North America. The blue calcite commonly occurs with minerals such as monticellite, vesuvianite, wollastonite, grossular garnet, diopside, scapolite, and numerous other contact-metamorphic minerals. More than two hundred mineral species have been reported from the Crestmore district, several of which were first recognized or extensively studied there. The specimen demonstrates the effects of contact metamorphism on carbonate rocks and serves as an introduction to skarn mineralization, fluid-rock interaction, and the development of metamorphic mineral assemblages. Creator An entity primarily responsible for making the resource Bereket Haileab Contributor An entity responsible for making contributions to the resource Bereket Haileab Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Riverside County, California GPS coordinates: 34.0171° N, 117.3983° W Date A point or period of time associated with an event in the lifecycle of the resource October 2023 Type The nature or genre of the resource Hand sample and thin section Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1hDAqS0anXN9YD052GsM0G-hOhSxJ0Dwq/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1LAOvL5hI1bfJFI2ldYpNSRShAqBUe0MO/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1LAQhpMadio5Wh5neauJDpdc7GkDGM3WD/preview" allow="autoplay"></iframe> Blue Calcite Calc-Silicate Minerals Calcite Contact Metamorphic Deposit contact metamorphism Crestmore Blue Calcite Crestmore Quarry Diopside Fluid-rock interaction Fluorellestadite Fluorescent Minerals Grossular Garnet Hydrothermal alteration Jurupa Valley Marble-Hosted Mineral metasomatism Monticellite rhombohedral cleavage Riverside County Scapolite skarn Sky Blue Hill Spinel Vesuvianite Vitreous Luster Wollastonite Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Metamorphic Rocks Subject The topic of the resource This collection includes slates, phyllites, schists, gneisses, eclogites, marbles, quartzites, skarns, granulites, and mylonites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-252 Subject The topic of the resource Garnet schist Description An account of the resource Garnet replaced with graphite Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Canada Date A point or period of time associated with an event in the lifecycle of the resource June 2026 Creator An entity primarily responsible for making the resource Bereket Haileab Contributor An entity responsible for making contributions to the resource Jon Cooper Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Metamorphic Rocks Subject The topic of the resource This collection includes slates, phyllites, schists, gneisses, eclogites, marbles, quartzites, skarns, granulites, and mylonites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-251 Subject The topic of the resource Eologite Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Canada Date A point or period of time associated with an event in the lifecycle of the resource June 2026 Creator An entity primarily responsible for making the resource Bereket Haileab Contributor An entity responsible for making contributions to the resource Jon Cooper https://bereket-haileab.geology.sites.carleton.edu/files/original/09fbadc4da0b237e6f859771c336c077.jpg b4085ee10cac21973507941cbb19cf6f Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Mineral Optics Gallery Subject The topic of the resource This collection contains minerals cut perpendicular to the c-axis in thin section. Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs. Contributor An entity responsible for making contributions to the resource Bereket Haileab Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-175d Subject The topic of the resource BXa figure of an aragonite mineral Creator An entity primarily responsible for making the resource Bereket Haileab Contributor An entity responsible for making contributions to the resource Bereket Haileab Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1dPb3IFYWvo1aO9LPnvN94JLFbhR_vWlZ/preview" allow="autoplay"></iframe> Description An account of the resource Sample BH250-175d was collected from Grand Canyon during field trips that I lead for Carleton Alumni trip. The sample exhibits a typical basaltic texture and well-developed hexagonal columnar jointing. Vesicles within the flow are commonly filled with secondary minerals, including aragonite. In one of the cavities, there are crystals of aragonite cut perpendicular to X that give beautiful BXa figure. Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Pumpkin Spring Pool, Grand Canyon, Arizona, USA Nearby Feature: Grand Canyon GPS Coordinates: 35°54'58.39"N, 113°20'2.21"W Date A point or period of time associated with an event in the lifecycle of the resource August 2021 Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample BH250-175d. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section and hand sample https://bereket-haileab.geology.sites.carleton.edu/files/original/cd5dde10ec5d810131c9a450b965fa41.jpg c55a35596ba02e10f0725e1f6c0c9f9f Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Mineral Optics Gallery Subject The topic of the resource This collection contains minerals cut perpendicular to the c-axis in thin section. Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs. Contributor An entity responsible for making contributions to the resource Bereket Haileab Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-8 Subject The topic of the resource BH250-8 length fast Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1oS4UNMax1vBejYY5eUtbcfncnfZy-7Yj/preview" allow="autoplay"></iframe> https://bereket-haileab.geology.sites.carleton.edu/files/original/399aaa1ffb90016e9fa144a8a2826e38.jpg fe84039368a17e6e1bbfac74858cfcc0 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Mineral Optics Gallery Subject The topic of the resource This collection contains minerals cut perpendicular to the c-axis in thin section. Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs. Contributor An entity responsible for making contributions to the resource Bereket Haileab Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-41 Subject The topic of the resource BH250-41 (Dunite) – Forsterite interference figures Description An account of the resource BH250-41 (Dunite) – Forsterite interference figures BH250-41 is an excellent sample for learning the optical behavior of forsteritic olivine in thin section. In this dunite, several olivine grains are cut nearly perpendicular to an optic axis and produce a distinctive interference figure. Begin by scanning the thin section in plane-polarized light (PPL) and crossed polars (XPL) for grains that are clean, inclusion-poor, and relatively broad in view. In XPL, the best grains for interference figure work are those that show slightly lower birefringence near the center than along the margins, suggesting that the grain is oriented close to one of the optic axes. Once such a grain is identified, center it carefully and switch to conoscopic observation. In BH250-41, these well-oriented olivine grains produce an interference figure in which the isogyre appears as a straight dark band rather than the curved, concave–convex isogyres seen in many other biaxial minerals. This is because forsterite has a very large 2V, close to 90°, so the optic axes are widely separated. As a result, the figure does not show the familiar curved brushes of a small-2V biaxial figure. Instead, students will observe a straight isogyre sweeping across the field. This is a key teaching point: the absence of strongly curved isogyres is itself diagnostic of a mineral with a very large optic axial angle. A common point of confusion is that students may interpret this straight isogyre as an off-centered uniaxial figure. However, careful observation resolves this. In olivine, the isogyre rotates or “spins” around the optic axis as the stage is turned, reflecting its biaxial nature and large 2V. In contrast, in a uniaxial mineral, an off-centered isogyre behaves differently—both ends of the isogyre move up and down symmetrically during stage rotation rather than rotating around a point. Recognizing this difference in movement is critical for distinguishing between biaxial olivine and uniaxial minerals such as calcite. To determine optic behavior more fully, insert the sensitive tint plate and rotate the stage. In this figure, you do not have a clear concave and convex side of the isogyre as you would in a small-2V biaxial figure. Instead, interpretation comes from watching how the addition and subtraction colors change as the stage rotates. In BH250-41, students should observe blue addition colors and yellow subtraction colors shifting position during rotation. The movement of these colors relative to the isogyre helps establish the vibration directions and reinforces the biaxial character of the mineral. A useful step-by-step approach is as follows. First, locate a suitable olivine grain in XPL, preferably one with a slightly subdued center. Second, center the grain precisely. Third, switch to conoscopic light and confirm the presence of a straight isogyre. Fourth, rotate the stage slowly and observe how the isogyre moves—specifically noting its rotational behavior rather than simple up-and-down motion. Fifth, insert the sensitive tint plate and track where blue addition and yellow subtraction develop and how these colors shift during rotation. This sequence guides students from grain selection to confident optical interpretation. BH250-41 is particularly valuable because it teaches students how olivine behaves in a natural ultramafic rock rather than in an idealized section. It also provides an excellent basis for comparison with other BH250 samples containing olivine, including BH250-82 (Hawaiian basalt), BH250-112 (Dish Hill xenolith), BH250-136 (Hawaiian xenolith), BH250-227, and Bh250-103b (Alta Stock marbles) where olivine is essentially pure forsterite (Mg₂SiO₄). Comparing these samples allows students to recognize consistent optical behavior across diverse geologic settings. Comparison with other minerals further strengthens interpretation. In calcite, a uniaxial mineral, the optic axis figure is centered with a black cross and concentric isochromes, and off-centered figures show symmetric motion of the isogyres. In talc, a biaxial mineral with small 2V, students observe curved isogyres and can use concave–convex geometry to determine optic sign. In forsterite olivine from BH250-41, however, the very large 2V produces a fundamentally different figure: a straight isogyre, widely separated optic axes, and diagnostic rotational behavior. Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1TFMweiUFlfx_CZdr5konqpY3688xrU0R/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1ecsjbkhjcqomvTr9iMPHCABFNW65KHR6/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1NKZYYB89d5aDJXEw2IHZCQiprJyzeJCz/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1RvzxN4kC6bCy5rj0GR7W0Y0vy1fXgaAl/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1FRACWu5QIyv1cTH6sRVVwMcj3W2S-k7k/preview" allow="autoplay"></iframe> 2V ~90° addition colors Alta stock marble Biaxial Mineral blue addition Dish Hill xenolith dunite fast axis forsterite Hawaiian basalt interference figure Isogyre isogyre behavior isogyre movement large 2V mantle minerals Mg2SiO4 Mica plate no concave convex isogyre olivine optic axes Optic Axis rotating isogyre Sensitive Tint Plate slow axis spinning isogyre straight isogyre subtraction colors Ultramafic rock vibration directions xenolith yellow subtraction https://bereket-haileab.geology.sites.carleton.edu/files/original/51e766245af92eb2d620ed0732b851e7.jpg 7b25295dcfa5079f4f58e6b3e01ebc94 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Mineral Optics Gallery Subject The topic of the resource This collection contains minerals cut perpendicular to the c-axis in thin section. Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs. Contributor An entity responsible for making contributions to the resource Bereket Haileab Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-103b Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1sissQ7z0uutf5R64SEcNzze_OTUAdtSe/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1dCSs984SXF2iKynuWgz_86d4e75Ev8TD/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1bq8Cg1wuFB16YiN-lGzAUoiyJWQwW-Fp/preview" allow="autoplay"></iframe> Subject The topic of the resource Centered Opic Axis Figure Description An account of the resource BH250-103b (Marble, Alta, Utah) – Calcite interference figures Calcite in BH250-103b provides a realistic and instructive setting for learning interference figures because students must find the right grain rather than being given a perfect orientation. Begin in PPL and XPL by scanning the mosaic of recrystallized calcite for grains that are clean, inclusion-poor, and as equant as possible. Unlike ideal teaching sections, most grains will not be perfectly oriented. The goal is to identify grains that show very low birefringence at their center in XPL, often appearing nearly dark or with subdued first-order colors—an indication that you are looking close to the optic axis (c-axis) of this uniaxial mineral. Once a promising grain is located, center it carefully and switch to conoscopic observation. With proper alignment, calcite will produce a uniaxial optic axis figure, characterized by a centered melatope and a dark cross (isogyres) that remains centered during stage rotation. Because calcite has high birefringence, the isochromes are vivid and well developed, making the figure easy to interpret once the correct grain is found. Small rotations of the stage should keep the cross stable and centered, confirming that you are truly looking down the optic axis. In addition, BH250-103b contains grains that are slightly off the ideal orientation, producing off-centered optic axis figures where the melatope remains within the field of view but is displaced from the center. In these cases, part of the isogyre will sweep toward or out of the field during stage rotation—an important intermediate condition that helps students understand how figures evolve with orientation. To complete the analysis, insert the mica (sensitive tint) plate. Calcite is optically negative, so you should observe characteristic color changes in opposite quadrants of the figure that correspond to the fast and slow vibration directions. You can also use a quartz wedge test, where additional colors move toward the melatope in the addition quadrantsand move away from it in the subtraction quadrants, reinforcing the interpretation of vibration directions and optic sign. The key teaching value of BH250-103b is that students must work through the process—scanning, rejecting poorly oriented grains, and refining their choice—before obtaining a clean interference figure. This builds the skill of recognizing the right grain in a natural rock, which is far more transferable than working with idealized samples. BH250-36 (Single calcite crystal, c ⟂ section) – Reference standard Calcite in BH250-36 represents an idealized case: a single crystal cut perpendicular to the c-axis, meaning you are already looking directly down the optic axis. In XPL, the grain will show very low birefringence at the center, and in conoscopic view it produces a perfect uniaxial optic axis figure with a sharply centered cross and concentric isochromes. The figure remains fixed during stage rotation, providing a textbook example of a uniaxial interference figure. While BH250-36 is useful as a reference for what a “perfect” figure looks like, it removes the most important step in real petrographic work—finding the correct grain. For that reason, students should rely on BH250-103b to develop their observational skills and use BH250-36 primarily as a visual benchmark for comparison and confirmation. addition of retardation addition quadrants Bertrand lens birefringence birefringent mineral blue quadrants Calcite carbonate mineral centered optic axis figure chromatic bands concentric rings conoscopic illumination conoscopic image conoscopic interference pattern conoscopic observation dark cross (Maltese cross) fast ray direction first-order colors gypsum plate higher-order colors Interference Colors interference rings isochrons Isogyres length slow / length fast melatop Mica plate Michel-Lévy colors optic axis determination optical axis (c-axis) optical sign colors Optical sign determination optical sign test petrographic microscope Quartz Wedge retardation retardation colors slow ray direction subtraction of retardation subtraction quadrants Uniaxial interference figure uniaxial mineral Uniaxial negative vibration directions yellow quadrants https://bereket-haileab.geology.sites.carleton.edu/files/original/0d93c7e9bf72d605a570719e5967a81f.jpg 6fd9e30e25bd66f16e1bddb6bcafb9cf Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Mineral Optics Gallery Subject The topic of the resource This collection contains minerals cut perpendicular to the c-axis in thin section. Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs. Contributor An entity responsible for making contributions to the resource Bereket Haileab Thin section Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-31 Subject The topic of the resource BXa = Biaxial optic axis figure Description An account of the resource BH250-31 offers an excellent opportunity to learn how to intentionally locate and use the “right” grain for interference figure work. In this talc–tremolite schist, begin in plane-polarized light (PPL) and crossed polars (XPL) by scanning for talc grains that appear clean, inclusion-free, and relatively equant in shape. The most useful grains are those cut in an orientation that allows you to look down the X direction, producing a Bxa (acute bisectrix) figure, where X = α = the fast vibration direction. In XPL, these grains will show very low birefringence at their center, often appearing nearly dark or displaying only very subdued interference colors. That is your first clue that you are looking down, or very close to, the appropriate optical direction and that you have found a grain capable of producing a high-quality interference figure. Once a suitable grain is identified, center it precisely in the field of view and switch to conoscopic observation, either by inserting the Bertrand lens or by removing the eyepiece. Carefully adjust the focus and illumination to bring out the interference figure. In BH250-31, well-oriented talc grains produce a clear Bxa acute bisectrix figure, meaning you are looking down the X direction (α, the fast vibration direction). The figure is characterized by a centered melatope and symmetrical isogyres. Because talc has low birefringence, the isochromes are subtle, but the geometry of the figure remains well defined. Small stage rotations should keep the melatope near the center, confirming that the grain is properly aligned for this interference figure. To refine the interpretation further, insert the mica (sensitive tint) plate. In this sample, the plate reveals a negative optic sign and a small 2V angle of about 12°. As the plate is inserted, observe the color changes in the quadrants, or in the concave and convex parts of the isogyres, and relate these changes to the slow and fast vibration directions. The combination of a centered Bxa figure, low birefringence at the grain center, and the response to the mica plate provides a complete step-by-step pathway from grain selection to optical interpretation, making BH250-31 a particularly effective teaching specimen for mastering interference figures. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample BH250-31. Housed at Carleton College in Minnesota Contributor An entity responsible for making contributions to the resource Bereket Haileab Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/16tixiecHCqGsAOJBGpxSPukF64NgQOCJ/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1I3oXtuEtPW3eOGtyXVciQ1OH3Ba8i14G/preview" allow="autoplay"></iframe> Publisher An entity responsible for making the resource available Bereket Haileab 2V angle Bertrand lens BXa optic axis conoscopic observation fast axis interference figure Isochromes Isogyres Low birefringence Melatope Mica plate optic axis figure optic sign negative Sensitive Tint Plate slow axis small 2V Talc talc tremolite schist Tremolite vibration directions https://bereket-haileab.geology.sites.carleton.edu/files/original/04c1254cd68c0735c0a4432cbf0f5e4e.jpg 2973c8e3b58e75ca13f1c19b3d74b561 https://bereket-haileab.geology.sites.carleton.edu/files/original/5a24763eaaec58384121542ba59ec94c.jpg b0b1da1f618cad1088c6179b7ec3fe4b https://bereket-haileab.geology.sites.carleton.edu/files/original/fe892e4efe98c50acea0b9d1872fbcf9.jpg 3b8bd18cd3457aab8eafaaa7caa93edb Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-258 Subject The topic of the resource Flint, Chert Description An account of the resource Flint, Cryptocrystalline quartz, Microcrystalline silica, Chalcedonic silica, Fine-grained silica The flint associated with the Brighton chalk is a variety of chert composed primarily of microcrystalline quartz (SiO₂). Although flint and chert are essentially the same siliceous rock, the term flint is traditionally applied to dark, dense chert occurring as nodules or bands within chalk and other limestones. It is considerably harder and more resistant to weathering than the surrounding chalk. The flint formed during diagenesis, after the calcareous sediment accumulated on the Cretaceous seafloor. Silica derived largely from marine organisms, particularly siliceous sponges and microorganisms, dissolved in pore water and migrated through the sediment before precipitating as microscopic quartz. This process produced irregular nodules, continuous bands and branching forms that may preserve ancient burrow systems. Weathered flint commonly develops a pale gray or white outer layer called a cortex or rind. This porous layer forms near the boundary between the flint nodule and the surrounding chalk, where silicification was less complete and microscopic carbonate or pore spaces may remain. Exposure to groundwater and surface weathering can dissolve the residual carbonate and further lighten the rind. The boundary between the pale cortex and the dark, dense interior is often sharp, emphasizing the original shape of the flint nodule. Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Brighton United Kingdom GPS Coordinates: 50°48'15.09"N, 0° 3'49.71"W Date A point or period of time associated with an event in the lifecycle of the resource August 2025 Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived SourceFrom the rock collection of Bereket Haileab. Sample BH250-258. Housed at Carleton College in Minnesota. Publisher An entity responsible for making the resource available Bereket Haileab Contributor An entity responsible for making contributions to the resource Bereket Haileab D. Haileab F. Kaleab Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1A9C3KcfClHgu8c-qa6SosjI_YkIx5Sbj/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1ARkqityVwWApH0tzjrpi6oujfHPm7WuJ/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1nnTGkwR2hJn3jwYdvfhSxiSNThxTaAkn/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1o1MsD2bTR9gB6G7Ar2Q2_G6yY1aBSJOq/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/19m56mODmkwnTuhb5zrv3j5DOK8TiVNXC/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/13lAmbyJRYgSSLLnP65rEnqmIByWvR2Qh/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/12MKXvVXz4G1eZqFoJ2S38sYMrKcNNgF-/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/18Za2NzYJcCeFyqNlDVMk0ThUkd8SRvYw/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/14CBy282VyNIbv-_QmYwQvA8QcrynBisz/preview" allow="autoplay"></iframe> Brighton Chalcedonic silica Chalk Group Chert chert nodules Cryptocrystalline Cryptocrystalline quartz Diagenesis Fine-grained silica flint Microcrystalline silica Nodular Chert Quartz sedimentary Silica United Kingdom Upper Cretaceous https://bereket-haileab.geology.sites.carleton.edu/files/original/ceec729fb937695c924a9d98e1ed8572.jpg 40c17f046e1fd7f6ae17c9594b72a87a Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Sedimentary Rocks Subject The topic of the resource This collection includes sandstones, limestones, breccias, conglomerates, dolostones, shales, oolites, and BIF. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Subject The topic of the resource Chalk Description An account of the resource Coccolith limestone, Biogenic limestone, Fossiliferous limestone, Micritic limestone, Calcite This chalk was collected from the Upper Cretaceous coastal outcrops near Brighton, East Sussex, England. The fine-grained limestone formed from calcareous marine microorganisms deposited in a warm sea approximately 85–75 million years ago. The Brighton-area succession belongs mainly to the White Chalk Subgroup and includes chalk containing marl seams, fossils and characteristic bands of dark flint. These cliffs form part of the South Downs and provide an excellent example of marine carbonate deposition, later silica replacement, groundwater dissolution and active coastal erosion. Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Brighton, United Kingdom GPS Coordinates: 50°48'15.09"N, 0° 3'49.71"W Date A point or period of time associated with an event in the lifecycle of the resource August 2025 Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample BH250-257. Housed at Carleton College in Minnesota. Publisher An entity responsible for making the resource available Bereket Haileab Contributor An entity responsible for making contributions to the resource Bereket Haileab D. Haileab F. Kaleab Type The nature or genre of the resource Hand sample Title A name given to the resource BH250-257 Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/18Za2NzYJcCeFyqNlDVMk0ThUkd8SRvYw/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/14CBy282VyNIbv-_QmYwQvA8QcrynBisz/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/13lAmbyJRYgSSLLnP65rEnqmIByWvR2Qh/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/12MKXvVXz4G1eZqFoJ2S38sYMrKcNNgF-/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1nnTGkwR2hJn3jwYdvfhSxiSNThxTaAkn/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1o1MsD2bTR9gB6G7Ar2Q2_G6yY1aBSJOq/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/19m56mODmkwnTuhb5zrv3j5DOK8TiVNXC/preview" allow="autoplay"></iframe> Biochemical sedimentary Biogenic limestone Biogenic origin Brighton Brighton Formation Calcite Carbonate rock Chalk chert nodules Coccolith limestone Coccolith-rich Cretaceous English Channel coast flint Fossiliferous Fossiliferous Limestone Marine Micrite Micritic limestone Sedimentary rock United Kingdom White Cliffs https://bereket-haileab.geology.sites.carleton.edu/files/original/2ba5398eb366f76ef6fd004b003ea5d8.jpg fd13ff336902ecee9aec9b01aa5edde2 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Igneous Rocks Subject The topic of the resource This collection covers both volcanic and intrusive rocks, including rhyolites, granites, diorites, andesites, basalts, gabbros, diabases, pumices, obsidians, syenites, phonolites, peridotites, carbonatites, dacites, trachyte, dunites, xenoliths, ignimbrites, and pegmatites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-250a Subject The topic of the resource Pillow Basalt Description An account of the resource Pillow Basalt sample showing a chilled margin, vesicles, vesicle pipes and Fe-Mn oxide coatings.<br /><br />BH250-250a specimen was collected in 2018 aboard the Nathaniel B. Palmer during a cruise to the South Atlantic Ocean, targeting the Rio Grande Rise. The sample was generously provided by Peter C. Davidson, whose contributions and scholarship is gratefully acknowledge. According to Peter’s personal communication, the exact coordinates of collection are 28.1133° S, 31.1755° W, at a feature named the Gienah Gurab Escarpment along the northern edge of the Rio Grande Rise in the Atlantic Ocean. The sample was recovered from a depth between 4300 and 3400 meters. <br /><br />BH250-250a is a fragment of a pillow basalt with striking characteristics. It contains numerous vesicles, including excellent examples of pipe vesicles, which indicate the basalt originally erupted in much shallower water than where it presently resides. Many of these vesicles are now partially filled with secondary clay minerals, giving the rock an amygdaloidal texture. Particularly notable is the sharp color transition from the reddish, oxidized, quenched outer rim (top view of the pillow basalt) to the greyer, more coarsely crystalline interior. <br /><br />This pattern reflects variations in cooling rate, oxidation, and alteration. A thin (~1 mm) Mn-oxide crust, visible along the sides and top of the specimen, records subsequent seafloor chemical processes. High-resolution photographs document all sides of the sample, highlighting the diversity in vesicle sizes, orientations, and the remarkable preservation of pipe vesicles. Reference: Davidson, P. C., Koppers, A. A. P., Class, C., Sager, W. W., &amp; Heaton, D. (2025). 40Ar/39Ar dating reveals over 30 million years of plume–ridge interaction formed the Rio Grande Rise. Communications Earth &amp; Environment, 6, 588. https://www.nature.com/articles/s43247-025-02572-y Thanks to Peter C. Davidson not only for generously sharing this specimen, but also for providing the detailed notes and context that make this catalog entry possible. Kein Dolge assisted with data collection. <br /><br />Chemical analysis: A quick chemical analysis was carried out on specimen BH250-250a using a Bruker portable handheld XRF. Measurements were taken from the bottom, the center, the chilled margin, and the top of the sample to compare chemical variations across the pillow basalt. The results show that the bottom, center, and chilled margin are consistent with a basaltic composition, with SiO₂ contents ranging from ~50–55 wt. %. The chilled margin (49.79 wt. % SiO₂) and the center (54.72 wt. % SiO₂) also contain moderate Al₂O₃ (14–18 wt. %), Fe (10–11 wt. %), MgO (2–5 wt. %), and Ca (3–5 wt. %), typical of basaltic glass and crystalline interiors. These values suggest the rock preserves its primary igneous composition. In contrast, the top of the pillow basalt exhibits strikingly different chemistry. It contains much lower SiO₂ (14.40 wt. %) and Al₂O₃ (3.08 wt. %), but is enriched in Fe (18.08 wt. %) and Mn (15.25 wt. %), along with elevated Cl (3.55 wt. %). These features indicate that the top is not primary basalt but rather a surface enriched in iron- and manganese-oxide precipitates. <br /><br />Such oxide coatings commonly develop on submarine basaltic surfaces, where hydrothermal or seawater interaction promotes the deposition of Fe–Mn crusts. Taken together, the data highlight the basaltic core of BH250-250aa while also documenting the secondary precipitation of Fe- and Mn-rich oxides on its outer surface, providing a clear chemical distinction between primary igneous composition and later seafloor alteration.<br /><br /><iframe width="1800" height="250" iframe="" src="https://docs.google.com/spreadsheets/d/e/2PACX-1vS4nyqCmZQGn3t6vX4g4nhDPwHMBaKrigt1LaY2pykWbBGXB1wNb6FYArx625I-JTtD7lyg4uz1OS1r/pubhtml?gid=1402521385&amp;single=true&amp;widget=true&amp;headers=false"></iframe> Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Rio Grande Rise, South Atlantic Ocean GPS coordinate: 28.1133° S, 31.1755° W Date A point or period of time associated with an event in the lifecycle of the resource 2018 Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. BH250-250a. Housed at Carleton College in Minnesota. Publisher An entity responsible for making the resource available Bereket Haileab Contributor An entity responsible for making contributions to the resource Bereket Haileab Peter C Davidson Type The nature or genre of the resource Hand Sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1K1E1CH2wzl1HG__3gvOhDb0rrJ1hg9-_/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1VfbG0S1wjXBZmQy1ntX6pXczbsF7_mYD/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1WMrfd40zvPao2Cp2JuF-PxPbiK30EF1r/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1Xm_ulB5etjHs-fo1GRUCjqfYnjs2ZNEP/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1gt6V8UFrht_7ekpfVzGDtEX6oVy5C2p3/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1cYTyvCceUYgSrgvcHYLf68_4mnR6sjK4/preview" allow="autoplay"></iframe> Amygdaloidal texture basalt Chemical precipitation (Fe–Mn crusts) Chilled margin Deep-sea basalt Fe–Mn crust formation Fe–Mn oxide precipitation Gas escape structures Gienah Gurab Escarpment Oceanic plateau Oxidation (outer rim) Pillow basalt Pillow lava formation Pipe vesicles Quenched margin Rapid quenching Rio Grande Rise Seafloor alteration Seafloor alteration record Seafloor chemical processes Seafloor weathering Shallow water eruption indicators South Atlantic Ocean Submarine volcanism Vesicle formation Vesicles vesicular basalt https://bereket-haileab.geology.sites.carleton.edu/files/original/4c9268402ac35d0d6931fffdf8248f85.jpg ffd9caa64763cb8b922585d0e2ea0707 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Igneous Rocks Subject The topic of the resource This collection covers both volcanic and intrusive rocks, including rhyolites, granites, diorites, andesites, basalts, gabbros, diabases, pumices, obsidians, syenites, phonolites, peridotites, carbonatites, dacites, trachyte, dunites, xenoliths, ignimbrites, and pegmatites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-208d Subject The topic of the resource Perovskite Mineral (Lava flow from Uganda) Description An account of the resource Major Minerals: perovskite (very large) Minot Minerals: phlogopite, clinopyroxene, muscovite, oxide (ilmenite) Optics: pseudo isotropic perovskite, grid-like or tartan plaid-like patterns Phase Transitions and Symmetry: Perovskite crystallizes in a high-symmetry cubic form at high temperatures but can undergo symmetry reduction upon cooling, transitioning to orthorhombic or monoclinic structures. This transition often results in pseudo-isotropic behavior and the appearance of grid-like or tartan-style twinning patterns under crossed polarizers. About the mineral Perovskite: Perovskite is an isotropic mineral with major significance across multiple disciplines geology, materials science, and solid-state chemistry. Chemical and Structural Characteristics: Chemical Formula: CaTiO₃ (calcium titanate) Crystal System: Cubic at high temperatures, but it commonly transforms to orthorhombic as the host lava cools. During this transformation, it retains a pseudo-isotropic appearance in thin section showing twining like features as it is seen in the photomicrographs and thin sections of BH250-208d. Being silica-poor, perovskite reacts with silica (SiO₂) to form sphene (titanite): CaTiO₃ + SiO₂ → CaTiSiO₅ Sphene (titanite) This reaction highlights its petrological behavior and links it to sphene (titanite), a mineral with similar optical properties. The similarities between the two are especially noticeable in thin section under polarized light. Geological Occurrence and Significance: For geologists, perovskite is an important accessory mineral found in, mafic and ultramafic rocks, Kimberlites and carbonatites and Mantle-derived xenoliths. Its high-pressure polymorph, is the most abundant mineral in Earth’s lower mantle, accounting for a significant portion of the planet's volume. This makes perovskite a cornerstone mineral in deep Earth research. Why should geology students care about Perovskite: Understanding perovskite is critical for grasping the structure and evolution of Earth’s interior, Its presence helps interpret seismic data and mantle composition. It can incorporate uranium while excluding lead, making it useful for U–Pb geochronology, especially in kimberlites. It hosts rare earth elements (REEs), niobium, and titanium critical elements in green energy technologies such as wind turbines, electric vehicles, and solar panels Optical and Physical Properties of Perovskite:  Brown, black, or reddish-brown in color and optically typically isotropic in cubic form, but may show weak anisotropy when preserved in orthorhombic symmetry making it pseudo -isotropic showing grid twining. In materials science and physics, synthetic perovskites are transforming solar cell technology. Perovskite is not just a mineral it is a structural archetype with deep relevance to both natural Earth processes and technological innovation. Whether it’s used to probe the deep mantle, date ancient rocks, or power future energy systems, perovskite sits at the intersection of geology, chemistry, and materials science. For future geologists, understanding perovskite means understanding how materials behave under extreme pressure and temperature, how elements cycle through the planet, and how science connects across disciplines to solve both ancient and modern challenges. Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Uganda Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample BH250-208d. Housed at Carleton College in Minnesota Contributor An entity responsible for making contributions to the resource Bereket Haileab Frank H. Brown Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/16vmgoh-LOnktydRQ-2UphPV7TY0KGadB/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1vtrvP-W7sQIR74beF4OhBxRXGrGZHuO7/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1nB5qcN7NKN7IsJ3D8GaLA4AMpCdXSKgy/preview" allow="autoplay"></iframe> 2.4 refractive index accessory minerals: Alkaline magmatism alkaline volcanic rock Clinopyroxene East African Rift euhedral perovskite fine-grained groundmass grid twining grid-like twinning high birefringence High refractive index mineral high relief igneous Ilmenite isotropic mineral (perovskite in XPL) mafic mafic volcanic rock mantle-derived magma massive perovskite crystals Orthopyroxene Oxide minerals Perovskite perovskite highest relief minerals porphyritic texture pseudo isotropic mineral pseudo isotropic perovskite REE-bearing phases tartan plaid-like patterns tartarn twining Ti-rich mineral assemblage titanium-rich phases twinned crystals twinned perovskite Uganda Ultramafic Volcanic Rock https://bereket-haileab.geology.sites.carleton.edu/files/original/39853dc017e57b7a3f7082142743f0f7.jpg c4ca1b81934baaca358d47d6b5c8bfd9 https://bereket-haileab.geology.sites.carleton.edu/files/original/040c796957fc88d4f44ea2ff6c59c7c9.jpg c4ca1b81934baaca358d47d6b5c8bfd9 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Igneous Rocks Subject The topic of the resource This collection covers both volcanic and intrusive rocks, including rhyolites, granites, diorites, andesites, basalts, gabbros, diabases, pumices, obsidians, syenites, phonolites, peridotites, carbonatites, dacites, trachyte, dunites, xenoliths, ignimbrites, and pegmatites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-250 Subject The topic of the resource Basalt Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant East Pacific Rise, recovered by HOV Alvin at 2500 m depth Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 250. Housed at Carleton College in Minnesota. Publisher An entity responsible for making the resource available Bereket Haileab Type The nature or genre of the resource Hand sample Description An account of the resource Mid-oceanic ridge basalt (MORB) from East Pacific Rise, showing glassy, basalt and a chilled margin. Petrologic and Mantle Significance: This mid-ocean ridge basalt (MORB) from the East Pacific Rise represents the dominant volcanic rock type forming the oceanic crust at divergent plate boundaries. It originated from partial melting of the upper mantle at depths of ~60–80 km. The presence of glass and a chilled margin reflects rapid quenching during submarine eruption, preserving the melt composition with minimal alteration. Geochemically, MORB is typically depleted in incompatible elements and exhibits relatively uniform isotopic ratios (e.g., low ⁸⁷Sr/⁸⁶Sr and high ¹⁴³Nd/¹⁴⁴Nd), indicating a well-mixed, depleted mantle source that has experienced prior melt extraction. Once analyzed for its chemistry and thin sections are made, this sample will serve as a valuable geochemical reference for understanding mantle composition, magma generation processes, and global mantle heterogeneity. Contributor An entity responsible for making contributions to the resource Bereket Haileab, Carleton College Geology Department Adam Soule '97 Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1HfKRYZDJ-neJAuKyLPHDDN0my1OQnPdx/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/19f70K0nJ0U2007yA4DfRg2u0qNOaYoXz/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1JqDsPYom35vJgcxBmxyG8vERFSOorom-/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1BfXwdQ7qlhX4-D149unPCLQ6OGps9Lwl/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/175deXA_R80TbsZht3wPxO6tZWq19o7xb/preview" allow="autoplay"></iframe> basalt Basalt glass Chilled margin Depleted mantle Divergent plate boundary East Pacific Rise Glass HOV Alvin igneous mafic Mid-Oceanic Ridge Basalt MORB Newest oceanic crust sample Oceanic crust Partial melting quenched glass Submarine basalt Submarine eruption Upper mantle melting volcanic Volcanic glass https://bereket-haileab.geology.sites.carleton.edu/files/original/616c4236b41a2aa210103288189c1ead.jpg 19fe60a2ae98f456bb9bc819be9a2b19 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Metamorphic Rocks Subject The topic of the resource This collection includes slates, phyllites, schists, gneisses, eclogites, marbles, quartzites, skarns, granulites, and mylonites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-249 Subject The topic of the resource Death Valley Metamorphic Basement Rock Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Death Valley, California, USA Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 249. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section and hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1oq2Wy3XL1E5hyrdHhLQP5oLDCLXx_p8K/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1ZgRLovHnxemUnNdDpx5PIKJemYSHv4d6/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/14tyD0b5yNnlb0A_bTbzkvDEs4Nww67h0/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1RipjvOH7c9gJdn_eoJq6GmiEZr1GLCtV/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1QWfyJtgG1DOyXdT1vRdai8bevt7h_WJf/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/11uowG8b5aGlvj06eYG0zGL75F51nabT-/preview" allow="autoplay"></iframe> <br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/17ACSpMKKuMkHif1nduGx48nL52SAsYZ_/preview" allow="autoplay"></iframe>&nbsp; metamorphic slate https://bereket-haileab.geology.sites.carleton.edu/files/original/be627a5a1d8ac8c8c62c9721d0203712.jpg bfc15653cc8a94c5529f5517737cb203 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Metamorphic Rocks Subject The topic of the resource This collection includes slates, phyllites, schists, gneisses, eclogites, marbles, quartzites, skarns, granulites, and mylonites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-238c Subject The topic of the resource Shale Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Death Valley, California, USA Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 238c. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1ukHDvpfLMUshINZd-cNTk8AFB0V5fd5I/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1hvGuyrnRzy6tnuosZThQOCw1dp3w4on0/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/17Z7GSGNy6t5nxe0NMvVU4MNIbCFMdgBQ/preview" allow="autoplay"></iframe> Description An account of the resource The laminated siltstones (BH250-238b) and shales (BH250-238c) of the lower Kingston Peak Formation in Death Valley are commonly found directly above the underlying Beck Spring Dolomite, marking an important stratigraphic and environmental transition in the late Precambrian basin. The contact typically records a change from shallow-water carbonate platform deposition of the Beck Spring Dolomite into deeper-water siliciclastic sedimentation represented by laminated mudstones, siltstones, and eventually diamictite-bearing (BH250-238 and BH250-239) intervals of the Kingston Peak. These finely laminated siltstones and shales represent quieter intervals of sedimentation that contrast strongly with the coarser diamictites interbedded higher in the section. Their thin bedding suggests settling of suspended clay and silt in low-energy offshore basins. When viewed together with the diamictites, they record repeated environmental shifts: calm background sedimentation interrupted by energetic pulses of glacial debris flows, iceberg rafting, or slope failure. Thus, the transition upward from the Beck Spring Dolomite into lower Kingston Peak mudrocks and diamictites captures the progressive breakdown of a stable carbonate shelf and the onset of tectonically active, climatically unstable Cryogenian conditions that ultimately became associated with Snowball Earth glaciation. Beck Spring Dolomite carbonate to clastic transition Cryogenian Cryogenian climate Death Valley Death Valley stratigraphy diamictite fine-grained sedimentary rocks Fissile shale glacial deposits iceberg rafting Kingston Peak Formation laminated siltstone mudstone Neoproterozoic Neoproterozoic basin evolution Pahrump Group Paleoenvironments shale siliciclastic transition Snowball Earth https://bereket-haileab.geology.sites.carleton.edu/files/original/72e061774fa1f949bc0cb9db5ee9352f.jpg 0c08e7fc3006c9a7773d795ca4a87e54 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Igneous Rocks Subject The topic of the resource This collection covers both volcanic and intrusive rocks, including rhyolites, granites, diorites, andesites, basalts, gabbros, diabases, pumices, obsidians, syenites, phonolites, peridotites, carbonatites, dacites, trachyte, dunites, xenoliths, ignimbrites, and pegmatites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-243c Subject The topic of the resource Ignimbrite/Tuff Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Death Valley, California, USA Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 243c. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section and hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1shS4Q0HIEj9Z0ObFr5Mej2Vqg_a-ePuj/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1W05Pwge5kQxq2toCkngHfs6Qx6UWvUfx/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/16sGLxqRaZNnMtq8RQyew1gjEC2vIoNJw/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1KWAJkWaX2rChOaWYkmh0Sf5B1Oy3PqMY/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/17FKg-V5l0COj5HGg-Fk0tkC1vRF9cdnl/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1DZzlnj5KVRoWgd9a7uU9SwqX_TmMqfJ_/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1uG08LOsTQiwa0luqb1Xt5w71DW1sDljh/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1QOraqkLrPtyk9a8Vrp3hxHmNOuxEfyaG/preview" allow="autoplay"></iframe> Description An account of the resource Major Minerals: Glass, sanidine BH250-243c represents the less-welded, more porous portion of the ignimbrite (BH250-243) exposed along Charlie Brown Road near Shoshone. This unit occurs toward the upper and lower parts of the Miocene Resting Spring Pass Tuff and provides an important contrast to the intensely welded vitrophyre (BH250-243b). Together, these layers offer a clear view of how conditions changed within a single pyroclastic flow deposit. This ignimbrite formed during a large explosive volcanic eruption that spread silicic ash and pumice across eastern California and Nevada, and was later tilted and exposed by Basin and Range extension. Like the rest of the ignimbrite, BH250-243c formed from a pyroclastic density current (nuée ardente)—a fast-moving, ground-hugging cloud of hot ash, pumice, crystals, and gas. However, in this part of the deposit, temperatures were lower compared to the central zone. As a result, the material did not fully compact and weld. Instead, it remained more open and porous, preserving more of its original fragmental character. Ash, pumice, and lithic fragments are still present, but they are less fused together than in the welded interior. This unit records the cooler margins of the ignimbrite, both above and below the hotter core. Unlike the dense, glassy vitrophyre, BH250-243c shows limited welding, meaning pumice fragments are less flattened and may retain more of their original shapes. The rock is typically lighter in color and more friable, with visible pore spaces. These features indicate that this part of the flow cooled more quickly and experienced less compaction. When viewed together with the welded zones and vitrophyre, BH250-243c helps define the vertical thermal gradient within the deposit. Although welding is weaker, you may still observe incipient eutaxitic fabric, where some pumice fragments show slight alignment. This suggests that the material was still moving and settling during deposition, but not at temperatures high enough to fully deform and fuse the pumice into strongly developed fiamme. In some areas, subtle alignment may still reflect flow direction and underlying topography. Compositionally, BH250-243c is also silicic, similar to rhyolite or dacite, and contains minerals such as quartz, feldspar, and biotite. Unlike the vitrophyre, however, much of the original glass has been altered or devitrified to fine-grained crystalline material. The higher porosity and lower degree of welding make this unit more susceptible to weathering and alteration. Even though pyroclastic flows can travel great distances, the presence of a thick, vertically zoned ignimbrite sequence—including the transition from poorly welded (BH250-243c) to densely welded zones and a central vitrophyre—indicates deposition from a hot, thick flow relatively close to its source (proximal to medial). The less-welded nature of BH250-243c reflects cooling at the margins of the flow, not a distal setting. Although the original vent or caldera is not preserved, these relationships allow us to infer that the source was likely a nearby Miocene silicic volcanic center in the southern Death Valley–eastern California region, probably within a few tens of kilometers. Overall, BH250-243c provides an important teaching example of the cooler, less-welded parts of a pyroclastic flow deposit and helps complete the picture of how temperature, compaction, and welding vary within an ignimbrite. ash-flow deposition Ash-flow tuff Basin and Range Province cristobalite Death Valley region devitrification eutaxitic fabric fiamme flattened pumice flow banding fragmental texture glass shards glassy ignimbrite igneous ignimbrite Lithic Fragments nuée ardente pyroclastic rock rhyolitic Sanidine Shoshone Silicic volcanic rock tridymite tuff vesicular pumice vitrophyre vitrophyric texture volcanic Volcanic glass volcaniclastic welded tuff welding https://bereket-haileab.geology.sites.carleton.edu/files/original/17072090491dcafc39fa2915de580287.jpg cc615bf77522b871aa952e5f8e3a092a Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Igneous Rocks Subject The topic of the resource This collection covers both volcanic and intrusive rocks, including rhyolites, granites, diorites, andesites, basalts, gabbros, diabases, pumices, obsidians, syenites, phonolites, peridotites, carbonatites, dacites, trachyte, dunites, xenoliths, ignimbrites, and pegmatites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-243b Subject The topic of the resource Vitrophyre Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Death Valley, California, USA Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 243b. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section and hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/192TcFA_w1gD-ao-ITjkEswgmuQv4e8Ix/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1MHQby6a2dRT6VBqJeTgrdzlmRhFtSf7F/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1DZzlnj5KVRoWgd9a7uU9SwqX_TmMqfJ_/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1uG08LOsTQiwa0luqb1Xt5w71DW1sDljh/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1QOraqkLrPtyk9a8Vrp3hxHmNOuxEfyaG/preview" allow="autoplay"></iframe> Description An account of the resource Major Minerals: glass, sanidine The vitrophyre (BH250-243b) exposed along Charlie Brown Road near Shoshone represents the most intensely welded and highest-temperature portion of the ignimbrite (BH250-243). It forms a dark, glassy layer within the Miocene Resting Spring Pass Tuff and provides a clear window into the thermal core of a pyroclastic flow deposit. This layer developed during a large explosive volcanic event that spread silicic ash and pumice across eastern California and Nevada. Later extension in the Basin and Range Province tilted and exposed the deposit, allowing us to observe this internal zone directly in the field. The vitrophyre formed from a pyroclastic density current (nuée ardente)—a fast-moving, ground-hugging cloud of hot ash, pumice, crystals, and gas. In this central part of the deposit, temperatures were extremely high, and the material remained soft and glass-rich after deposition. Instead of simply settling, the ash and pumice compacted and fused together, behaving almost like a viscous fluid before solidifying. This process produced the dense, obsidian-like texture that characterizes the vitrophyre. This layer marks the hottest zone within the ignimbrite and sits within a broader pattern of vertical cooling. Above and below the vitrophyre are zones of welded tuff where pumice has been flattened into lens-shaped features called fiamme. These surrounding layers are still strongly welded, but not to the same degree as the vitrophyre. Farther toward the top and bottom of the deposit, the rock becomes less welded (BH250-243c) and more porous, reflecting cooler conditions during and after deposition. Together, these layers record how temperature varied through the thickness of the pyroclastic flow. Although the vitrophyre itself is typically massive and glassy, it is closely associated with rocks that display eutaxitic fabric, where flattened pumice fragments are aligned in the direction of flow. This relationship helps link the glassy core to the broader flow dynamics of the ignimbrite. In some areas, these fabrics suggest that the pyroclastic flow moved across uneven or sloping ground rather than settling in a flat basin. Compositionally, the vitrophyre is silicic, similar to rhyolite or dacite, and was originally dominated by volcanic glass. Over time, parts of this glass may begin to change into very fine crystals through devitrification, although the vitrophyre often preserves more glass than the surrounding welded tuff due to rapid quenching and high initial temperatures. Even though pyroclastic flows can travel great distances, the presence of a well-developed vitrophyre indicates that this part of the deposit remained extremely hot and thick during emplacement. This is strong evidence that the ignimbrite at this location formed relatively close to its volcanic source (proximal to medial) rather than far away. Large, flattened fiamme in adjacent layers and the overall thickness of the deposit support this interpretation. Although the original vent or caldera is not visible today, these features allow us to infer that the source was likely a nearby Miocene silicic volcanic center in the southern Death Valley–eastern California region, probably within a few tens of kilometers. Overall, the vitrophyre (BH250-243b) provides a powerful teaching example of how the hottest part of a pyroclastic flow deposit behaves and how geologists can use textures and layering to reconstruct volcanic processes and estimate distance from the source. ash-flow deposition Ash-flow tuff Basin and Range Province cristobalite Death Valley region devitrification eutaxitic fabric fiamme flattened pumice flow banding fragmental texture glass shards glassy ignimbrite igneous ignimbrite Lithic Fragments nuée ardente pyroclastic rock rhyolitic Sanidine Shoshone Silicic volcanic rock tridymite vesicular pumice vitrophyre vitrophyric texture volcanic Volcanic glass volcaniclastic welded tuff welding https://bereket-haileab.geology.sites.carleton.edu/files/original/cac9c6bd0644e3c54ef57cc1612761bd.jpg 735cdf215df9b6a1036e452cababcbc0 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Metamorphic Rocks Subject The topic of the resource This collection includes slates, phyllites, schists, gneisses, eclogites, marbles, quartzites, skarns, granulites, and mylonites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-242b Subject The topic of the resource Marble Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Death Valley, California, USA Mosaic Canyon California GPS coordinates: 36°34'7.45"N, 117° 8'28.24"W Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 242b. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section and hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1D5uKi9-NNr0bYsJ2Aa6BOuhZJLXeAV5L/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1dMaYimLZdUUGlJfFV3JuUlcAzgqTV9MR/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1jqewSmp1mcIVXwyFrUV-XGrIrog-HOtw/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1E-1H31S4dZWjUF3jf-x-TSDdoIvlmU0j/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1jENs2jAyvYXVTaOh5oX1QuFc96v4ILC-/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1vvLz77wp4F05H2SThKDCkLpmDTbp26mG/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1EygQ-QRjkPgFtujLb4Ga7VNUWe6yW-Z1/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/17Z7GSGNy6t5nxe0NMvVU4MNIbCFMdgBQ/preview" allow="autoplay"></iframe> Description An account of the resource The marble from Mosaic Canyon in Death Valley comes from a classic carbonate sequence exposed along the western part of the valley, composed mainly of Paleozoic limestone and dolostone deposited in shallow marine environments along the passive margin of western North America. In Mosaic Canyon, much of this marble is derived from units such as the Noonday Dolomite and overlying limestones, later metamorphosed under low- to moderate-grade conditions to produce a recrystallized, interlocking calcite texture. The rock commonly preserves subtle banding, stylolites, and pressure-solution features, and locally records minor deformation. The canyon’s distinctive smooth, polished, and fluted walls are the result of sediment-laden flash floods that have sculpted the marble surfaces. Overall, the marble records a history of marine deposition, metamorphism, and tectonic exhumation, followed by ongoing surface erosion (Mike Smith, Class of 1999, personal communication). Basin and Range Province Carbonate rock Death Valley Dolostone protolith limestone protolith marble metamorphic metamorphic rock Mosaic Canyon Noonday Dolomite recrystallized calcite stylolites https://bereket-haileab.geology.sites.carleton.edu/files/original/9ebd0a2f2687227ac704807339741736.jpg 84776fa230ba2e6ed87d006c29760a7a https://bereket-haileab.geology.sites.carleton.edu/files/original/28fb57457f16c8dd4ba6b74b01eda380.jpg c489d10743a1abf2510d5b24a4551450 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Igneous Rocks Subject The topic of the resource This collection covers both volcanic and intrusive rocks, including rhyolites, granites, diorites, andesites, basalts, gabbros, diabases, pumices, obsidians, syenites, phonolites, peridotites, carbonatites, dacites, trachyte, dunites, xenoliths, ignimbrites, and pegmatites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-241e Subject The topic of the resource Xenolith without basalt Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Death Valley, California Nearby Geographic Feature: Death Valley GPS Coordinates: 35.940906, -116.732639 Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 241e. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1gbk0jLu0HSdKVaOEPsvojiPApCKf0sRR/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1rNiKaS92aDFiRAMa2swHwsjyZJWWX2Ul/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1lYUogiDYX_6W9nJk29dshfEfVMmF7ie1/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/13cMPJfnIeaCbseuOz4v9NNpoV39B4_rh/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1CsLxdnQhpRcKOulCRPfkTDYUwdn-dPWm/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/14_gFupSUdnIDauG6I-W8-xB7Uc_PcxOu/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1Fo1tCCysJaGPIdJOsLTtGSCsmiHsKgss/preview" allow="autoplay"></iframe> Description An account of the resource Cinder cones are beautiful volcanic features that decorate the landscape. The Split Cinder Cone in southern Death Valley is a Pleistocene-age volcano that has been split and displaced by movement along the active Southern Death Valley Fault Zone. Located near West Side Road and Highway 178, the western part of the cone has been offset approximately 225 meters north relative to the eastern portion by right-lateral strike-slip faulting, a relationship that can be observed both in the field and on satellite imagery. In addition to the beautiful structural features visible at this site, the cinder cone preserves several notable volcanic characteristics, including volcanic bombs and chilled margins. Another important aspect of this outcrop is the abundance of xenoliths, which were carried to the surface by the magma and are exposed throughout the cone. Some of these xenoliths are felsic in composition, indicating that the magma incorporated shallow granitic country rock during ascent. Five samples were collected from this locality, including a volcanic bomb and several xenoliths: BH250-241a, BH250-241b, BH250-241c, and BH250-241e. igneous xenolith https://bereket-haileab.geology.sites.carleton.edu/files/original/0c7dc65e2e03821c799852192c858cfa.jpg 07cf2a0e2e733e7c108e9bfc77c59f1e https://bereket-haileab.geology.sites.carleton.edu/files/original/cb4f7f3a0ec5853d76359b54ddb4c252.jpg c489d10743a1abf2510d5b24a4551450 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Igneous Rocks Subject The topic of the resource This collection covers both volcanic and intrusive rocks, including rhyolites, granites, diorites, andesites, basalts, gabbros, diabases, pumices, obsidians, syenites, phonolites, peridotites, carbonatites, dacites, trachyte, dunites, xenoliths, ignimbrites, and pegmatites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-241d Subject The topic of the resource Xenolith without basalt Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Death Valley, California, USA Nearby Geographic Feature: Death Valley GPS Coordinates: 35.940906, -116.732639 Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 241d. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section and hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/16hncEyNbJ9FJNMazUBwTzYhiOFKNhoDL/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1L8s02MJqHXcpLFca6QKHYuU7I5KRaBGF/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/10TCMQ3xMybsQfcjx6pW0wr7XThMM5Q7v/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1y3jAmOvvdwmIWwYSkExtuXrEynBDsvh1/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1ecm3b7yVIH10voZ61SF6gjTMJ16fD4sH/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1CsLxdnQhpRcKOulCRPfkTDYUwdn-dPWm/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/14_gFupSUdnIDauG6I-W8-xB7Uc_PcxOu/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1Fo1tCCysJaGPIdJOsLTtGSCsmiHsKgss/preview" allow="autoplay"></iframe> Description An account of the resource Cinder cones are beautiful volcanic features that decorate the landscape. The Split Cinder Cone in southern Death Valley is a Pleistocene-age volcano that has been split and displaced by movement along the active Southern Death Valley Fault Zone. Located near West Side Road and Highway 178, the western part of the cone has been offset approximately 225 meters north relative to the eastern portion by right-lateral strike-slip faulting, a relationship that can be observed both in the field and on satellite imagery. In addition to the beautiful structural features visible at this site, the cinder cone preserves several notable volcanic features, including volcanic bombs and chilled margins. Another important characteristic of this outcrop is the presence of abundant xenoliths, which were brought to the surface by the lava and are exposed throughout the cinder cone. Some of these xenoliths are felsic in composition, indicating that the magma incorporated shallow granitic country rock during ascent. Five samples were collected from this site, including a volcanic bomb and several xenoliths: BH250-241a, BH250-241b, BH250-241c, and BH250-241e. basaltic volcanism bomb sag Chilled margins cinder cone country rock fragments crustal xenoliths Death Valley Death Valley National Park desert geology displaced volcano fault offset felsic xenoliths geomorphology granitic xenoliths igneous Pyroclastic deposits right-lateral fault scoria Split Cinder Cone strike-slip faulting volcanic bombs Volcanic Breccia volcanic cone Volcanic textures xenolith xenoliths https://bereket-haileab.geology.sites.carleton.edu/files/original/670a6ac9cdba93253593f9b8f3235e0f.jpg b28d7d14bc583bf9920ecf183dae3f29 https://bereket-haileab.geology.sites.carleton.edu/files/original/a07f85346dd9c58cb6aea2bfbf3ff221.jpg c489d10743a1abf2510d5b24a4551450 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Igneous Rocks Subject The topic of the resource This collection covers both volcanic and intrusive rocks, including rhyolites, granites, diorites, andesites, basalts, gabbros, diabases, pumices, obsidians, syenites, phonolites, peridotites, carbonatites, dacites, trachyte, dunites, xenoliths, ignimbrites, and pegmatites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-241c Subject The topic of the resource Xenolith (in a basalt) Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Death Valley, California, USA Nearby Geographic Feature: Death Valley GPS Coordinates: 35.940906, -116.732639 Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 241c. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1QGlaXgxywAPmXYTXcWIwsNHTpmHkb1-L/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1FBCfV1jmunYiqQSPqNCUHZ8pfMw3BM1c/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1CsLxdnQhpRcKOulCRPfkTDYUwdn-dPWm/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/14_gFupSUdnIDauG6I-W8-xB7Uc_PcxOu/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1Fo1tCCysJaGPIdJOsLTtGSCsmiHsKgss/preview" allow="autoplay"></iframe> Description An account of the resource Cinder cones are beautiful volcanic features that decorate the landscape. The Split Cinder Cone in southern Death Valley is a Pleistocene-age volcano that has been split and displaced by movement along the active Southern Death Valley Fault Zone. Located near West Side Road and Highway 178, the western part of the cone has been offset approximately 225 meters north relative to the eastern portion by right-lateral strike-slip faulting, a relationship that can be observed both in the field and on satellite imagery. In addition to the beautiful structural features visible at this site, the cinder cone preserves several notable volcanic features, including volcanic bombs and chilled margins. Another important characteristic of this outcrop is the presence of abundant xenoliths, which were brought to the surface by the lava and are exposed throughout the cinder cone. Some of these xenoliths are felsic in composition, indicating that the magma incorporated shallow granitic country rock during ascent. Five samples were collected from this site, including a volcanic bomb and several xenoliths: BH250-241a, BH250-241b, BH250-241c, and BH250-241e. basaltic volcanism bomb sag Chilled margins cinder cone country rock fragments crustal xenoliths Death Valley Death Valley National Park desert geology displaced volcano fault offset felsic xenoliths geomorphology granitic xenoliths igneous Pyroclastic deposits right-lateral fault scoria Split Cinder Cone strike-slip faulting volcanic bombs Volcanic Breccia volcanic cone Volcanic textures xenolith xenoliths https://bereket-haileab.geology.sites.carleton.edu/files/original/40697afb05a26ec3c940af42a729e002.jpg 5862f9debe1da66df2cfe192c241949e https://bereket-haileab.geology.sites.carleton.edu/files/original/72d28654f248a0be785062a24cd1af8a.jpg c489d10743a1abf2510d5b24a4551450 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Igneous Rocks Subject The topic of the resource This collection covers both volcanic and intrusive rocks, including rhyolites, granites, diorites, andesites, basalts, gabbros, diabases, pumices, obsidians, syenites, phonolites, peridotites, carbonatites, dacites, trachyte, dunites, xenoliths, ignimbrites, and pegmatites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-241b Subject The topic of the resource Xenolith (with basalt rim) Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 241b. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section and hand sample Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Death Valley, California, USA Nearby Geographic Feature: Death Valley GPS Coordinates: 35.940906, -116.732639 Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1wiGbMkH05OYtnPnXFap3663GFxEqbz0D/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/11xcVmM_tPxmgo7E6KROSImwZopje-3fB/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1W9srYs-EkNUK9Tnp0JDKiNHCFgytoDD6/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1TOk9Y-ONnAeEbqvEBhyXS6HqIyhLITAF/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1AA6y4jYPbIdUq1ZRF8EytBIfkX-x10CZ/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1ciW8ectI5ZqKsLSvOZ02j6pULO_d69Ri/preview" allow="autoplay"></iframe> <br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1HGDx2_xY9KIvAL-bcfMQ1tXvauh3MuxV/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1CsLxdnQhpRcKOulCRPfkTDYUwdn-dPWm/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/14_gFupSUdnIDauG6I-W8-xB7Uc_PcxOu/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1Fo1tCCysJaGPIdJOsLTtGSCsmiHsKgss/preview" allow="autoplay"></iframe> Description An account of the resource Cinder cones are beautiful volcanic features that decorate the landscape. The Split Cinder Cone in southern Death Valley is a Pleistocene-age volcano that has been split and displaced by movement along the active Southern Death Valley Fault Zone. Located near West Side Road and Highway 178, the western part of the cone has been offset approximately 225 meters north relative to the eastern portion by right-lateral strike-slip faulting, a relationship that can be observed both in the field and on satellite imagery. In addition to the beautiful structural features visible at this site, the cinder cone preserves several notable volcanic features, including volcanic bombs and chilled margins. Another important characteristic of this outcrop is the presence of abundant xenoliths, which were brought to the surface by the lava and are exposed throughout the cinder cone. Some of these xenoliths are felsic in composition, indicating that the magma incorporated shallow granitic country rock during ascent. Five samples were collected from this site, including a volcanic bomb and several xenoliths: BH250-241a, BH250-241b, BH250-241c, and BH250-241e basaltic volcanism bomb sag Chilled margins cinder cone country rock fragments crustal xenoliths Death Valley Death Valley National Park desert geology displaced volcano fault offset felsic xenoliths geomorphology granitic xenoliths igneous Pyroclastic deposits right-lateral fault scoria Split Cinder Cone strike-slip faulting volcanic bombs Volcanic Breccia volcanic cone Volcanic textures xenolith xenoliths https://bereket-haileab.geology.sites.carleton.edu/files/original/bcf3d51f7196b683ac0224bc44e1f1ce.jpg 177580bd4bb5f48858b75683b8d8884d Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Sedimentary Rocks Subject The topic of the resource This collection includes sandstones, limestones, breccias, conglomerates, dolostones, shales, oolites, and BIF. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs. Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-238b Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 238b. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section and hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1LWx-jAz2BBNMtFTHKdVUcFLhgi6rBVJ8/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1LhgFXYaeV7gIl9HqUKZRD4AD9cuNrAYu/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1f9tD4DZPwGd_ENgG-FZM1yTOn2JRt1Pa/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1-o14uKapTRt_z1sYd5Gnqrfpd1U2ti35/preview" allow="autoplay"></iframe> <br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1HxVYOFxUmhfWWj0pewqZMww5D8GDSwHG/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1hvGuyrnRzy6tnuosZThQOCw1dp3w4on0/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/17Z7GSGNy6t5nxe0NMvVU4MNIbCFMdgBQ/preview" allow="autoplay"></iframe> Description An account of the resource The laminated siltstones (BH250-238b) and shales (BH250-238c) of the lower Kingston Peak Formation in Death Valley are commonly found directly above the underlying Beck Spring Dolomite, marking an important stratigraphic and environmental transition in the late Precambrian basin. The contact typically records a change from shallow-water carbonate platform deposition of the Beck Spring Dolomite into deeper-water siliciclastic sedimentation represented by laminated mudstones, siltstones, and eventually diamictite-bearing (BH250-238 and BH250-239) intervals of the Kingston Peak. These finely laminated siltstones and shales represent quieter intervals of sedimentation that contrast strongly with the coarser diamictites interbedded higher in the section. Their thin bedding suggests settling of suspended clay and silt in low-energy offshore basins. When viewed together with the diamictites, they record repeated environmental shifts: calm background sedimentation interrupted by energetic pulses of glacial debris flows, iceberg rafting, or slope failure. Thus, the transition upward from the Beck Spring Dolomite into lower Kingston Peak mudrocks and diamictites captures the progressive breakdown of a stable carbonate shelf and the onset of tectonically active, climatically unstable Cryogenian conditions that ultimately became associated with Snowball Earth glaciation. Beck Spring Dolomite carbonate to clastic transition Cryogenian Cryogenian climate Death Valley Death Valley stratigraphy diamictite fine-grained sedimentary rocks Fissile shale glacial deposits iceberg rafting Kingston Peak Formation laminated siltstone mudstone Neoproterozoic Neoproterozoic basin evolution Pahrump Group Paleoenvironments shale siliciclastic transition Snowball Earth https://bereket-haileab.geology.sites.carleton.edu/files/original/eb49132157b7131b0771a6a9c14fb4ba.jpg 2fd8d21224b01446d6ae81dbc5f3f08c Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Metamorphic Rocks Subject The topic of the resource This collection includes slates, phyllites, schists, gneisses, eclogites, marbles, quartzites, skarns, granulites, and mylonites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-100b Subject The topic of the resource Morton Gneiss Saprolite Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample BH250-100b. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section and hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1mOc2BS7Vg1m6E3b1yMYTA36A8wpAm_W_/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1gn8tlnjMrfYRa3ms8ldKvkxPcLitLf8x/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1Nz_iUR2cawp-FhSC1WWcfyktbDeA1vsV/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1TDjHd3mnxS25TUm2aluHkq_s9f29vYgd/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1-hKYzkR74MwLYyRXzFfi3a03Tj64Hojz/preview" allow="autoplay"></iframe> Description An account of the resource The Morton Saprolite near Redwood Falls, Minnesota, formed through deep chemical weathering of the Precambrian Morton Gneiss, one of the oldest rock units on Earth. As the gneiss weathers, it produces a distinctive mineral assemblage including quartz, kaolinite, sericite (white mica), gibbsite, goethite, and hematite. Despite extensive mineralogical alteration, the saprolite preserves the original fabric and banding of the gneiss — a hallmark feature of saprolitic weathering. The weathered material is typically reddish to yellowish-brown, reflecting the abundance of iron oxides. This saprolite has been the subject of multiple geochemistry student research projects, particularly focusing on its mineralogy, weathering processes, and geochemical evolution. Documentation and findings from these student studies are available through resources linked on this website. Several student projects have explored this subject; please refer to the papers, abstracts, and posters available on the Geochemistry of Natural Waters website. For more discussion on the Morton Saprolite see BH250-100 Clay Mineral Clay Mineral Formation Deep Chemical Weathering Element Mobility Feldspar weathering Geochemical Weathering Gibbsite Goethite Hematite Hydrolysis Immobile Element Concentration Kaolinite Leaching metamorphic Minnesota Minnesota River Valley Morton Gneiss Paleosaprolite Potassium Loss Precambrian Rare Earth Element (REE) Enrichment Redwood Falls Redwood Falls Minnesota Regolith Residual Soil saprolite Saprolitic Weathering Sericite Sericite Separation Silica Depletion Southwestern Minnesota Weathered Gneiss White mica https://bereket-haileab.geology.sites.carleton.edu/files/original/be4ce6d8c5b0126f7a4f471dee880c3a.jpg b94e1024127717980d446a9ff01641aa Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Metamorphic Rocks Subject The topic of the resource This collection includes slates, phyllites, schists, gneisses, eclogites, marbles, quartzites, skarns, granulites, and mylonites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-100d Subject The topic of the resource Morton Gneiss Saprolite Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 100d. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section and hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1ZUxIutARyFAutj7cLfjUADwYjZaJAL1r/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1IYc9HMlN-M20cAl7T_nB8-5JwByv5w1f/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1Ox7z5csyTdSPbYh-dTLiww7-lYF1gjfc/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1fEzKQ0uju82UkN65RL4p6Rsc4C8VVFcE/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1fJQOkrmVOFABWVQXad-IMgHJ7t9wNJVh/preview" allow="autoplay"></iframe> Description An account of the resource The Morton Saprolite near Redwood Falls, Minnesota, formed through deep chemical weathering of the Precambrian Morton Gneiss, one of the oldest rock units on Earth. As the gneiss weathers, it produces a distinctive mineral assemblage including quartz, kaolinite, sericite (white mica), gibbsite, goethite, and hematite. Despite extensive mineralogical alteration, the saprolite preserves the original fabric and banding of the gneiss — a hallmark feature of saprolitic weathering. The weathered material is typically reddish to yellowish-brown, reflecting the abundance of iron oxides. This saprolite has been the subject of multiple geochemistry student research projects, particularly focusing on its mineralogy, weathering processes, and geochemical evolution. Documentation and findings from these student studies are available through resources linked on this website. This rock/saprolite is the least weathered Morton Geniss. Several student projects have explored this subject; please refer to the papers, abstracts, and posters available on the Geochemistry of Natural Waters website. For more discussion on the Morton Saprolite see BH250-100 Clay Mineral Clay Mineral Formation Deep Chemical Weathering Element Mobility Feldspar weathering Geochemical Weathering Gibbsite Goethite Hematite Hydrolysis Immobile Element Concentration Kaolinite Leaching metamorphic Minnesota Minnesota River Valley Morton Gneiss Paleosaprolite Potassium Loss Precambrian Rare Earth Element (REE) Enrichment Redwood Falls Redwood Falls Minnesota Regolith Residual Soil saprolite Saprolitic Weathering Sericite Sericite Separation Silica Depletion Southwestern Minnesota Weathered Gneiss White mica https://bereket-haileab.geology.sites.carleton.edu/files/original/2d6fff3a2442d2023e22e19a8283d43d.jpg 5b680cc4c7adac8ceb2d8ba9454d8b77 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Metamorphic Rocks Subject The topic of the resource This collection includes slates, phyllites, schists, gneisses, eclogites, marbles, quartzites, skarns, granulites, and mylonites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-100c Subject The topic of the resource Morton Gneiss Saprolite Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 100c. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section and hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1lK8eyzzs5OVRH2PMjHr0kgY881X0gf_4/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1zT67ROMJQ0o3yUTRcTbGAQnPBj8zJAoC/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1-giicKdg6v1WZUI5fW6TpvP68fpyVWrh/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1y3O4UVrhU8oxZ9YbAV3vMdnQ44jNn7Dr/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1l8Nu1UeKvcH0SjoL1LOFTC2ZDWyPsAKZ/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1JHmVGtuMN0V2BtDVJYFjqNPUBbTvSh0j/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/10U8ZghFT95XCm7e0gwop5sPgUqh2rrxo/preview" allow="autoplay"></iframe> Description An account of the resource The Morton Saprolite near Redwood Falls, Minnesota, formed through deep chemical weathering of the Precambrian Morton Gneiss, one of the oldest rock units on Earth. As the gneiss weathers, it produces a distinctive mineral assemblage including quartz, kaolinite, sericite (white mica), gibbsite, goethite, and hematite. Despite extensive mineralogical alteration, the saprolite preserves the original fabric and banding of the gneiss a hallmark feature of saprolitic weathering. The weathered material is typically reddish to yellowish-brown, reflecting the abundance of iron oxides. This part of the sample is less weathered Morton Gneiss than BH250-100, 100b This saprolite has been the subject of multiple geochemistry student research projects, particularly focusing on its mineralogy, weathering processes, and geochemical evolution. Documentation and findings from these student studies are available through resources linked on this website. Several student projects have explored this subject; please refer to the papers, abstracts, and posters available on the Geochemistry of Natural Waters website. For more discussion on the Morton Saprolite see BH250-100 Clay Mineral Clay Mineral Formation Deep Chemical Weathering Element Mobility Feldspar weathering Geochemical Weathering Gibbsite Goethite Hematite Hydrolysis Immobile Element Concentration Kaolinite Leaching metamorphic Minnesota Minnesota River Valley Morton Gneiss Paleosaprolite Potassium Loss Precambrian Rare Earth Element (REE) Enrichment Redwood Falls Redwood Falls Minnesota Regolith Residual Soil saprolite Saprolitic Weathering Sericite Sericite Separation Silica Depletion Southwestern Minnesota Weathered Gneiss White mica https://bereket-haileab.geology.sites.carleton.edu/files/original/83d35d90ba4d6b51b4318c7875c4ba2a.jpg c60f828f2573172bbf4f1492124333c7 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Metamorphic Rocks Subject The topic of the resource This collection includes slates, phyllites, schists, gneisses, eclogites, marbles, quartzites, skarns, granulites, and mylonites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-52b Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample BH250-52b. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section and hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1YEKsI_ZBCJWTmGyudq8rSr6BF91GUKbk/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1B0sH6RGpZFfRK1Ufx__X0_8mgetVXbW6/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1S9nJ8TNbyK8GAtbNjNptY3BCEON9wtVV/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1Q80IpQiolPMjPtZtW7TU1NW2LVH2TQ7W/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/17nFNa_zJ7AJLT-PSjkYhXoy-sC9agF4e/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/128s5Sj1pPT19sAVmjfR7pUklMUTKRwh7/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1IGPCL83-aMhefwbbhUciebw1zbFGNfCr/preview" allow="autoplay"></iframe> Subject The topic of the resource Garnet Schist (from the same location as BH250-52) Description An account of the resource Major Minerals: Quartz, plagioclase, albite, biotite, hypersthene Minor Minerals: Garnet, clinopyroxene Optical Features: Biotite displays bird's-eye maple interference pattern and strong pleochroism Texture: Strong foliation; pre-kinematic (pre-tectonic) garnet growth Note: BH250-52b is from the same location as BH250-52 with more garnets Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Granite Falls, Minnesota, USA GPS Coordinates: 44 48 06.07 N, 95 32 26.18 W Contributor An entity responsible for making contributions to the resource Bereket Haileab Biotite pleochroism Bird's-Eye Extinction Bronzite Clinopyroxene Foliated Metamorphic Rock Garnet Granite Falls Minnesota Hypersthene Metamorphic Texture Minnesota Rive Valley Orthopyroxene Pre-Kinematic Garnet Strong Foliation https://bereket-haileab.geology.sites.carleton.edu/files/original/a4fa0637f553bf0b8a4dcf4e75e386e0.jpg 4541fd6593b966cb160663b09d03541e https://bereket-haileab.geology.sites.carleton.edu/files/original/e59151e8502db747658a3dd2bb97d8c5.jpg 8c69d2e4c418e23054e53a40d10bcb55 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Metamorphic Rocks Subject The topic of the resource This collection includes slates, phyllites, schists, gneisses, eclogites, marbles, quartzites, skarns, granulites, and mylonites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-118c Subject The topic of the resource Amphibolite Description An account of the resource Major Minerals: amphibole, biotite, orthoclase BH250-118, BH250-118b, and BH250-118c are samples collected from the Morton Gneiss in Morton, Minnesota. The Morton Gneiss is one of the oldest known rocks in North America and is a widely studied example of high-grade metamorphic rock. It is prominently exposed in southwestern Minnesota, particularly around the town of Morton, from which it takes its name. Here, active quarries reveal striking outcrops of the gneiss, displaying its distinctive banding. Historically, the rock was quarried for use in tabletops, building walls, and tombstones, and quarrying continues today under the ownership of a company based near St. Cloud. The site has also been of academic interest, with recent Carleton College graduate Emma Watson (Class of 2023) completing her comprehensive thesis on the Morton Gneiss. The Morton Gneiss is Archean in origin, with its protolith (original rock) forming around 3.6 billion years ago. Since its formation, it has undergone multiple episodes of metamorphism and deformation, most notably during the Penokean orogeny (~1.85 billion years ago) and later thermal/metamorphic overprinting during the Proterozoic. It is a banded, migmatitic gneiss, showing evidence of both solid-state metamorphism and partial melting (migmatization). The rock features interlayered felsic bands (BH250-118), mafic bands (BH250-118b), and amphibolite (BH250-118c), each representing different compositions, origins, and metamorphic histories. Amphibolite (BH250-118c) is present as lenses or layers within the Morton Gneiss and represents metamorphosed mafic rocks that may have originated as basaltic or gabbroic intrusions, or as volcanic sediments. Amphibolite in this setting is dominated by hornblende and plagioclase, typically lacking quartz. It can occur conformably with the gneissic layering or as discordant bodies, suggesting emplacement as dikes during or before metamorphism. Geologically, the Morton Gneiss is significant because it preserves a record of early Earth crustal evolution, including crust formation, tectonism, and high-grade metamorphism. It forms part of the Minnesota River Valley subprovince, which is itself a key component of the Superior Province of the Canadian Shield. Interestingly, in the past, outcrops of the Morton Gneiss were considered as potential storage sites for radioactive waste, and remnants of that period—including test wells and excavated pits—can still be seen in certain locations. Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Granite Falls, Minnesota, USA 44°49'7.94"N, 95°33'52.44"W Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 246. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1tbGznYh1FAhOfRKxgkRgQ41QQxxTq42t/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/13xiGU89DDm8VQ1dU4WuQePR0lxDxCqWA/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1tnMHw5oIbopk88dP7o6nbT_yZUUeRPN7/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1vs9q7m9Uxitd8soiisAWUOcpXp5UFoNQ/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1YYrDK3R59iryYxQBJWIrX0ts_Iysu1b-/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1v3F5vz19z_LijXjMH9b0bH26cgqHF6sL/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1U5ets6zsvvNbK4-Ix5Oq7-SjWXZ1FKxV/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1wP1dBGW3zLn2i409RlmanQMfl-qgRR2-/preview" allow="autoplay"></iframe> <iframe width="100%" height="480" src="https://drive.google.com/file/d/1FHy8p7Y2S3QIDGfPCQgYlTy5LjvO-3tX/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/1bD4xkklyf0aZQyNIcuEKp41_RLVsJtyd/preview" allow="autoplay"></iframe> amphibolite Amphibolitized Intrusion Archean Gneiss Banded Gneiss Canadian Shield Felsic Gneiss gneiss Granitic Protolith High-Grade Metamorphic Rock Leucosome Veins Mafic Gneiss metamorphic Metamorphosed Mafic Rock Migmatitic Gneiss Minnesota Minnesota River Valley Subprovince Morton Morton Gneiss Partial Melting Features Penokean Orogeny Proterozoic Overprinting Quartz-K-feldspar-Plagioclase-Biotite Radioactive Waste Test Site https://bereket-haileab.geology.sites.carleton.edu/files/original/510eb006e7748e2bb90e4cf7619ee55f.jpg 25a45ac3c6587e94ef80b61ef4e4e878 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Sedimentary Rocks Subject The topic of the resource This collection includes sandstones, limestones, breccias, conglomerates, dolostones, shales, oolites, and BIF. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs. Hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-122wc Subject The topic of the resource Decorah Shale Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Wangs Corner, Warsaw Township, Minnesota, USA GPS Coordinates: 44.410464, -92.983144 Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample BH250-122wc. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1aQDB35K8-PUReNwaypSxF0-Rsjb16fis/preview" allow="autoplay"></iframe> Creator An entity primarily responsible for making the resource Bereket Haileab Description An account of the resource BH250-122wc is a sample collected from the Decorah Shale at Wangs Corner, Warsaw Township, Minnesota. This site is a regular destination for both introductory and upper-level geology students, offering a remarkable glimpse into one of the most fossiliferous outcrops in the Midwest. Despite recent access challenges involving the landowner, it remains an invaluable location for studying Upper Ordovician stratigraphy and fossil preservation. The Decorah Shale directly overlies the Platteville Limestone and consists of fine-grained, greenish-gray shale interbedded with occasional carbonate lenses. The outcrop is rich in articulate brachiopods and bryozoans, disarticulated crinoid, gastropods, bivalves, cephalopods, rugose corals, and trilobites. Sibo Wang, Class of 2010, conducted her senior comprehensive project at this site. Her research includes detailed documentation of the fossil assemblage and provides a valuable resource for future study. Bivalves Brachiopods Bryozoans Cephalopods Crinoids Decorah Shale Fossiliferous Outcrop Gastropods Goodhue County Rugose Corals Senior Comps Sibo Wang Trilobites Wangs Corner Warsaw Township https://bereket-haileab.geology.sites.carleton.edu/files/original/515327bdaa683126fc0ee909a004bf8d.jpg 06fa9f5efa02c78344bb5ee698190d24 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Igneous Rocks Subject The topic of the resource This collection covers both volcanic and intrusive rocks, including rhyolites, granites, diorites, andesites, basalts, gabbros, diabases, pumices, obsidians, syenites, phonolites, peridotites, carbonatites, dacites, trachyte, dunites, xenoliths, ignimbrites, and pegmatites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-94b, BH250-94c, BH250-94d Subject The topic of the resource Olivine-Bearing Gabbro (Stillwater Complex, Montana) Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: near Stillwater, Montana, USA Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample BH250-94b, 94c, and 94d. Housed at Carleton College in Minnesota. Contributor An entity responsible for making contributions to the resource Bereket Haileab John Goodge, '80 Type The nature or genre of the resource Hand Sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1eqGAKgltEzpq94X6qyurzJN_yK9gwNge/preview" allow="autoplay"></iframe>&nbsp;&nbsp;<br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1xuDXaSLvgr6zB0fTQNXHumkUcUZkQr-9/preview" allow="autoplay"></iframe> Creator An entity primarily responsible for making the resource Bereket Haileab Description An account of the resource Olivine-Bearing Gabbro (Stillwater Complex, Montana) Major Minerals: plagioclase, olivine Minor Minerals: serpentine, oxides Location: Stillwater Complex, Montana, USA BH250-94b, c and d are particularly valuable teaching specimens from the Stillwater Complex of Montana, one of the world’s classic layered mafic intrusions. This specimen is a hand sample only and does not have an associated thin section, making it especially useful for teaching students how much information can still be extracted from careful hand-sample observation alone. The specimen was collected and generously donated by John Goodge, Carleton College Class of 1980, adding an important alumni connection to the teaching collection. Like BH250-93, these samples helps students explore crystallization sequences in mafic magmas, but it records a contrasting pathway in which the original melt composition likely favored early crystallization of mafic minerals. The abundance of dark mafic minerals relative to plagioclase suggests a more magnesium- and iron-rich parental magma compared with BH250-93. BH250-94b, c and d are dominated by plagioclase and olivine, with minor oxide minerals and secondary serpentine produced through alteration of olivine. The presence of serpentine provides an excellent opportunity to discuss how olivine commonly becomes unstable during later hydrothermal alteration or low-temperature weathering processes. These secondary minerals remind students that igneous rocks often preserve both primary crystallization histories and later alteration events. Although these specimens lacks a thin section, they remains highly effective for teaching simplified phase equilibria in mafic systems when paired with BH250-93. Students can compare the relative abundance of minerals in hand sample and infer that the original melts occupied different positions on a phase diagram. BH250-93 likely formed from a melt that favored early plagioclase crystallization, whereas BH250-94b likely originated from a more mafic melt in which olivine crystallized earlier. For introductory students, BH250-94b, c and d demonstrates how mineral proportions and textures visible in hand sample can reveal magmatic history. For advanced petrology students, it becomes an excellent example for discussing parental magma composition, layered intrusions, fractional crystallization, and alteration processes within the Stillwater Complex. Together with BH250-93, this sample helps illustrate how two rocks with similar names can preserve very different crystallization histories. gabbro igneous mafic plutonic https://bereket-haileab.geology.sites.carleton.edu/files/original/3f9295e125640f9dde720776a9a9ec99.jpg a0f9ec064f08922e33f2046e389a4b85 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Igneous Rocks Subject The topic of the resource This collection covers both volcanic and intrusive rocks, including rhyolites, granites, diorites, andesites, basalts, gabbros, diabases, pumices, obsidians, syenites, phonolites, peridotites, carbonatites, dacites, trachyte, dunites, xenoliths, ignimbrites, and pegmatites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-89b Subject The topic of the resource Baxter Hollow Granite: (Probable Source Rock for the Baraboo Quartzite) Description An account of the resource Major Minerals: orthoclase, quartz, plagioclase Minor Minerals: zircon, Fe-Ti oxides, apatite, chlorite, calcite, sericite BH250-89b represents the Baxter Hollow Granite, one of the most important basement rocks associated with the evolution of the Baraboo Quartzite because it likely served as a major sediment source for the quartz sands that eventually became the Baraboo Quartzite. The Baxter Hollow Granite is part of the crystalline basement exposed in the Baraboo Range and is Paleoproterozoic in age, generally dated to approximately 1,760–1,830 Ma, making it slightly older than deposition of the Baraboo Quartzite, which occurred roughly between 1,750–1,630 Ma. The granite formed during early Proterozoic magmatic events along the southern margin of the Superior Craton prior to deposition of the Baraboo sedimentary sequence. It was later uplifted, exposed at Earth’s surface, and subjected to prolonged weathering and erosion before its sediments were transported into the basin where the Baraboo Quartzite accumulated. Mineralogically, the Baxter Hollow Granite is a felsic intrusive rock composed primarily of quartz, potassium feldspar, plagioclase feldspar, and biotite, with minor muscovite, zircon, magnetite, and accessory Fe-Ti oxides. Chemically, it is silica-rich and enriched in potassium, sodium, and aluminum, which is typical of evolved granitic magmas. Quartz is particularly important because of its resistance to chemical weathering, whereas feldspars are far less stable under surface conditions and readily alter through hydrolysis. For example, potassium feldspar can weather to clay minerals through reactions such as: 2KAlSi3O8 + 2H+ + 9H2O → Al2Si2O5(OH)4 + 4H4SiO4 + 2K+ Calcium-rich plagioclase may weather through reactions such as: CaAl2Si2O8 + 2CO2 + 3H2O → Al2Si2O5(OH)4 + Ca2+ + 2HCO3- These reactions break down feldspars into clay minerals while releasing dissolved ions into groundwater, leaving quartz as the most durable surviving mineral. Texturally, BH250-89b displays a medium-grained phaneritic texture (figure xx). Quartz typically occurs as glassy anhedral grains, potassium feldspar may show pink to salmon coloration, plagioclase is commonly white to gray, and biotite occurs as dark flaky grains. In outcrop and hand samples, the granite may appear relatively undeformed and may not clearly show the effects of later low-grade metamorphism associated with regional tectonic events. However, thin section observations reveal subtle evidence of this overprinting. Quartz grains commonly display undulose (wavy) extinction (see thin sections of BH250-89b), indicating that the granite experienced mild deformation and recrystallization during later tectonic events, likely related to regional metamorphism associated with the Penokean Orogeny. The transformation of the Baxter Hollow Granite into the sediment that formed the Baraboo Quartzite required prolonged weathering, erosion, transport, and sedimentary reworking. Once uplifted and exposed at the surface, the granite underwent physical weathering through fracturing, thermal expansion, and mechanical breakdown. Chemical weathering attacked feldspars and mafic minerals, converting them into clays and dissolved ions, while resistant quartz grains remained intact. Rivers transported these quartz grains into shallow marine and coastal environments, where repeated wave action and longshore transport further removed unstable minerals and concentrated nearly pure quartz sand. Over time, this extreme sedimentary maturation transformed granite-derived sediment into one of North America’s most mature quartz arenites. By the time these sediments were deposited in the basin that became the Baraboo Quartzite, most feldspar, lithic fragments, and unstable minerals had been eliminated, leaving behind the exceptionally pure quartz-rich sandstone seen today. During later burial and deformation associated with the Penokean Orogeny, those sands were metamorphosed into quartzite. BH250-89b therefore preserves the beginning of the Baraboo Quartzite story, the crystalline source rock that had to be weathered, transported, and transformed before one of Wisconsin’s most iconic quartzites could form. Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Baraboo, Wisconsin, USA GPS Coordinates: 43.385406, -89.798408 Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample 89b. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Hand Sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1fF2jtBeeGpO-XgqKkjSG7yfoiAor7Wsp/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1Nskh_QPRrTClXgJQb2Azcn04moi4p4Ty/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1yGsXTyIlIj3QJ3raKQrbwir6kvd0s2MC/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1hqFX9u-QxBT2dYlgAmLc3XGX2TBpjSbG/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1czy0XgXPWmoZcqwcrVy-LWRAGOFNNoqY/preview" allow="autoplay"></iframe><iframe width="100%" height="480" src="https://drive.google.com/file/d/168YHSl2Tq61NIFpFgVLUBuRQqK8hobfH/preview" allow="autoplay"></iframe> Creator An entity primarily responsible for making the resource Bereket Haileab Baraboo Quartzite context Baraboo Range Baxter Hollow Baxter Hollow Granite felsic granite igneous Paleoproterozoic plutonic Proterozoic granite Wisconsin geology https://bereket-haileab.geology.sites.carleton.edu/files/original/0682e02036ba09e506ca4ebec3d8451f.jpg 7a2d882a5723d41e0edb508f8fa16f2e Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Metamorphic Rocks Subject The topic of the resource This collection includes slates, phyllites, schists, gneisses, eclogites, marbles, quartzites, skarns, granulites, and mylonites. Creator An entity primarily responsible for making the resource Bereket Haileab Source A related resource from which the described resource is derived Housed in Anderson Hall, Carleton College. Format The file format, physical medium, or dimensions of the resource Thin sections, thin section scans, hand samples, hand sample images, photomicrographs, chemical analyses (major elements, trace elements and REE analyses for selected samples). Thin section and hand sample Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource BH250-80b Subject The topic of the resource Serpentinized Peridotite Source A related resource from which the described resource is derived From the rock collection of Bereket Haileab. Sample BH250-80b. Housed at Carleton College in Minnesota. Type The nature or genre of the resource Thin section and hand sample Relation A related resource <iframe width="100%" height="480" src="https://drive.google.com/file/d/1EgLa3doiwVTG4N-VkPuc6_USVDOwfTpd/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1LlxYrJCy_AvhxjKBYC48iAn-KkoKEBHr/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1uHgZQZeIrh9PPL1AYer8gm7wjKjDveTr/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1qSMlcVWFcTKwIw1AHv38wKeLYxM-cSdq/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1dRTqeVuqyFxAvjCWo2SjEzZkAi5bK3ee/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1IbwiRa9mC1q97ALfxBW_rc-zbhVtmjuH/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1E1HKbZPtTMtcdiSC3pLd1HkEZq2QlFwd/preview" allow="autoplay"></iframe><br /><br /><iframe width="100%" height="480" src="https://drive.google.com/file/d/1d9mNHNf8tEt4ZvETVCMVXZr_qqy7Twnq/preview" allow="autoplay"></iframe>width="640" height="480" iframe="" <iframe width="640" height="480" src="https://drive.google.com/file/d/1nwnG3lTWUealES0LWiUFi8flFyy4ptl7/preview" allow="autoplay"></iframe> Coverage The spatial or temporal topic of the resource, the spatial applicability of the resource, or the jurisdiction under which the resource is relevant Location: Upper Peninsula, Michigan, USA Presque Isle 46°35'35.95"N 87°22'48.63"W Creator An entity primarily responsible for making the resource Bereket Haileab Description An account of the resource Major Mineral: serpentine Minor Mineral: olivine altered to serpentine BH250-86b is a sample collected from the Upper Peninsula of Michigan, specifically from the tip of Presque Isle. It represents part of an ultramafic body commonly known as the Presque Isle Peridotite. This body is unconformably overlain by the Jacobsville Sandstone, a widespread Proterozoic sedimentary unit prominently exposed along the southern shoreline of Lake Superior. Degree of Alteration: The Presque Isle peridotite has undergone extensive serpentinization, a hydrothermal alteration process in which primary minerals like olivine and pyroxene have been transformed into serpentine minerals, predominantly antigorite and lizardite. The resulting rock is a magnetite-rich serpentinite, characterized by a bluish-green color and weak magnetism due to the presence of fine-grained magnetite. Petrographic analysis of thin sections confirms that the original plagioclase lherzolite has been altered to serpentinite. Secondary minerals such as chlorite and calcite are present, indicating ongoing interaction between the rock and circulating fluids during and after the serpentinization process. Conjugate Fractures: The outcrop at this site exhibits well-defined conjugate fracture sets, which are clearly visible in the field and documented in photographs. These fractures play a significant role in both structural deformation and chemical alteration. Fluid movement through these fractures is evident from mineral-filled veins and alteration halos surrounding them. Conjugate fractures occur in pairs, typically intersecting at high angles—often between 60° and 70°. In the Presque Isle peridotite, they are found cutting across massive serpentinite and other altered ultramafic zones. These fractures often act as conduits for fluid flow and are commonly filled with secondary minerals such as calcite, serpentine, or chlorite. Their formation is attributed to a combination of tectonic stress and hydration-induced volume expansion. As olivine and pyroxene transform into serpentine minerals during serpentinization, the rock undergoes a net volume increase—typically up to 30–40%. This expansion generates internal pressure, which contributes to the development of these brittle fracture networks, facilitating further alteration and mineral deposition. Contributor An entity responsible for making contributions to the resource Bereket Haileab Calcite veins Conjugate fractures Fluid-rock interaction Hydrothermal alteration Jacobsville Sandstone metamorphic peridotite Presque Isle Peridotite Proterozoic Geology Serpentine Minerals Serpentinization serpentinized peridotite ultramafic Ultramafic rock Upper Peninsula Michigan Volume expansion