Ronald Amundson

University of California, Berkley, USA

Biography

Ronald Amundson is Professor of Pedology at the University of California at Berkeley. During his career, he has focused on the stable isotope geochemistry of soils, the soil carbon cycle, and human impacts on soils and terrestrial ecosystems. Much of his research has been devoted to understanding how soil and related geomorphic processes vary in relation to climate, in order to better understand how climate change may affect soils and ecosystems, and how to better interpret climates of the past, on both Earth and Mars, from soil and geological records.

Abstract: Paleohydrology in present deserts

Present deserts represent the current configuration of global climate systems and rainfall patterns. The environmental history leading to this current configuration is important for understanding such issues as ground water recharge and archaeological records. There are several well accepted means of reconstructing past hydrology, such as the sedimentological and paleobotanical records of basin (lake or marshland) sediments. These records, while insightful, suffer as all records do, by certain limitations. In this talk, I will review how an integrated perspective of fluvial deposits, stream channel profiles, hillslope soils and features, and soil profile geochemistry, when combined can provide a strong and independent perspective on long-term hydrological changes in modern deserts. The specific desert examined will be the Atacama Desert of northern Chile, the driest desert on Earth but one with a still debated climate history. Detailed field observations, combined with chemical analyses, cosmogenic isotope determinations of landform ages and erosion rates, and geomorphic modeling, are used to quantitatively and qualitatively assess oscillations in precipitation rates since the Miocene. The combined record, and its interpretation, provides a novel view of the Desert’s paleohydrology, and demonstrates the utility of a methodology that should be applicable to other desert regions.