Wearing Away Mountains

Abstract

GEOLOGY The Himalayas are thought to be one of the most rapidly eroding regions on Earth. Knowledge of their erosion rate today and over the long term is needed for understanding the relations among climate, tectonics, and erosion. Weathering of silicate rocks also helps to remove carbon dioxide from the atmosphere. Most estimates of erosion in this region have been made from studies that average over several million years. An approach that provides a better estimate of current erosion rates is the study of cosmogenic nuclides—isotopes that are produced in rocks through bombardment with cosmic rays. Vance et al . examined several areas across the Himalayas and found erosion rates varying up to 2.7 mm per year in the High Himalaya. Comparison with other data suggests that erosion and exhumation rates have been balanced for the past several thousand to few million years. Current rates of erosion are higher than earlier rates, implying that there has been a fairly recent increase in the exhumation rate of the range. — BH Earth Planet. Sci. Lett . 206 , 273 (2003).