Post-glacial climate change in the Rocky Mountains from isotopic records of ferricrete deposits

Dartmouth College, Hanover NH

Investigators

Abstract

This award is for a stable isotopic study of ferricrete deposits in the Rocky Mountains of the western United States. The purpose of this study is to understand the nature of climate change during the current interglacial in the Rocky Mountains. The primary importance of this study is the investigation of rapid climate change (last 10,000 years) in high alpine catchments which should be sensitive to local and regional climate perturbations. This project makes use of variations in oxygen isotope ratios of goethite from ferricretes through time. Ferricrete deposits are found throughout the American west in areas of naturally acidic waters, typically near sulfide-rich rocks. These ferricrete deposits consist of goethite-cemented stream sediments that can be meters thick and which entombed datable wood fragments. The investigator's previous research has shown that ferricretes are an important new climate indicator which is useful in terrestrial, mountainous areas where few other climate proxies currently exist.