BH250-247c
Title
BH250-247c
Subject
Pumice
Description
BH250-247a, b, c and d
Belbel, Botolan, Zambales lies on the western flank of Mount Pinatubo and represents a proximal volcaniclastic environment shaped directly by the 1991 eruption and its aftermath. During that eruption, enormous volumes of pyroclastic flows swept down the slopes of the volcano, depositing thick, hot mixtures of ash, pumice, and lithic fragments. In areas like Belbel, these deposits are commonly preserved as massive, poorly sorted units with abundant pumice and angular clasts, reflecting rapid emplacement from high-energy flows. Because of the short transport distance from the vent, the materials here tend to be coarser and less reworked than those found farther away, and primary volcanic textures are often well preserved.
Following the eruption, the landscape was rapidly transformed by intense seasonal rainfall and typhoons, which remobilized loose pyroclastic material into lahars (volcanic debris flows). In Belbel, these lahars reworked earlier deposits but still retained a strong proximal signature, producing thick accumulations of debris-flow deposits interbedded with channelized units. These deposits are typically matrix-supported, with a muddy ash-rich groundmass surrounding a wide range of clast sizes, from fine ash to boulders. Repeated lahar events built up a stratigraphic sequence of stacked flow units, recording pulses of sediment transport tied to climatic events in the years following the eruption.
Geomorphically, the Belbel area reflects an evolving volcanic landscape transitioning from eruption-dominated processes to sedimentary reworking. Channels are often deeply incised into earlier deposits, and terraces mark former lahar levels, indicating ongoing adjustment of the drainage system. Compared to more distal areas such as the Tarlac plains, Belbel preserves a clearer link to the volcanic source, with deposits that are thicker, coarser, and less modified by prolonged transport. As a result, this area provides an excellent natural laboratory for understanding proximal facies of volcanic systems, the interaction between pyroclastic and sedimentary processes, and the rapid reshaping of landscapes following major explosive eruptions. Samples from this area were collected by Jaren Yambing (Class of 2022).
Belbel, Botolan, Zambales lies on the western flank of Mount Pinatubo and represents a proximal volcaniclastic environment shaped directly by the 1991 eruption and its aftermath. During that eruption, enormous volumes of pyroclastic flows swept down the slopes of the volcano, depositing thick, hot mixtures of ash, pumice, and lithic fragments. In areas like Belbel, these deposits are commonly preserved as massive, poorly sorted units with abundant pumice and angular clasts, reflecting rapid emplacement from high-energy flows. Because of the short transport distance from the vent, the materials here tend to be coarser and less reworked than those found farther away, and primary volcanic textures are often well preserved.
Following the eruption, the landscape was rapidly transformed by intense seasonal rainfall and typhoons, which remobilized loose pyroclastic material into lahars (volcanic debris flows). In Belbel, these lahars reworked earlier deposits but still retained a strong proximal signature, producing thick accumulations of debris-flow deposits interbedded with channelized units. These deposits are typically matrix-supported, with a muddy ash-rich groundmass surrounding a wide range of clast sizes, from fine ash to boulders. Repeated lahar events built up a stratigraphic sequence of stacked flow units, recording pulses of sediment transport tied to climatic events in the years following the eruption.
Geomorphically, the Belbel area reflects an evolving volcanic landscape transitioning from eruption-dominated processes to sedimentary reworking. Channels are often deeply incised into earlier deposits, and terraces mark former lahar levels, indicating ongoing adjustment of the drainage system. Compared to more distal areas such as the Tarlac plains, Belbel preserves a clearer link to the volcanic source, with deposits that are thicker, coarser, and less modified by prolonged transport. As a result, this area provides an excellent natural laboratory for understanding proximal facies of volcanic systems, the interaction between pyroclastic and sedimentary processes, and the rapid reshaping of landscapes following major explosive eruptions. Samples from this area were collected by Jaren Yambing (Class of 2022).
Coverage
Location: Belbel, Botolan, Zambales, Philippines
Nearby Geographic Feature: Mt. Pinatubo
GPS Coordinates: 15.170000, 120.346944
Nearby Geographic Feature: Mt. Pinatubo
GPS Coordinates: 15.170000, 120.346944
Creator
Bereket Haileab
Source
From the rock collection of Bereket Haileab. Sample 247c. Housed at Carleton College in Minnesota.
Contributor
Jaren Yambing, '22
Type
Thin section and hand sample
Relation
Collection
Citation
Bereket Haileab, “BH250-247c,” BH250 Mineralogy Teaching Collection, accessed April 24, 2026, https://bereket-haileab.geology.sites.carleton.edu/items/show/329.