T6 Heterogeneity in Geomorphic Systems: Driving Forces and Landscape Response

Sunday, 25 September 2016
8:00 AM - 12:00 PM
Room 405

DUELING EROSION FRONTS: GLACIAL BUZZCUTTING AND NONGLACIAL SCARP ENCROACHMENT LIMIT THE HEIGHT OF TROPICAL MOUNTAINS

Paper number: T6-12
Program: Technical Sessions
Time: 10:55 AM – 11:10 AM

Authors

Abstract

Large-scale topographic analyses show that most mid-latitude mountain ranges have hypsometric maxima that lie between the modern and LGM ELAs. Such observations have given rise to the “glacial buzzsaw” hypothesis, which says that ice-driven erosion is effective enough to limit vertical orogen growth. Here we present evidence that glacial buzzcutting is also an important process in tropical mountain ranges, even though evidence of glaciation there is often limited to small, isolated patches. We hypothesize that climate variation in high tropical mountains leads to glacial and fluvial erosion taking turns driving landscape evolution.

Our work combines surface-exposure age dating of glacial landforms, field mapping, remote sensing, and topographic analysis to characterize the imprint of glacial erosion in the Talamanca Range of Costa Rica and the Central Range of Taiwan. 10Be dating of glacial landforms at Cerro Chirripó in Costa Rica confirms LGM timing of glacial erosion, and topographic analysis shows that LGM buzzcutting has occurred in both places. Fluvially driven escarpments currently propagate headward into extinct glacial valleys, and scarp encroachment into buzzcut landscapes appears to act quickly enough to erase most glaciated terrain during warm periods. We deduce that this oscillatory pattern of erosion has acted throughout the Pleistocene in these and other tropical ranges, often obscuring evidence of past glaciations. Ironically, the height of many of these hot, humid landscapes has been limited by erosion during cold phases.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-279307

© Copyright 2016 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.