"Over 40,000 atoms counted this year."

Current research projects -- Spatial variation in erosion rates, southeast Tibet The first step towards understanding the influence of erosion on the tectonics of a particular orogen is actually figuring out what erosion rates are, and how they vary in space. As part of the NSF Geodynamics of Indentor Corners project, we are measuring Be-10 in river sands from the eastern Himalayan syntaxis in an effort to better understand the geomorphic and geodynamic evolution of this spectacular, rapidly eroding, and rapidly deforming region. More information: here and here.    Burial dating of glacial tills, north-central U.S. Here we're using a neat application of cosmogenic-isotope systematics to determine the age since burial for glacial till sequences in Minnesota and adjacent states. This is important because these sediments comprise the terrestrial record of Laurentide Ice Sheet advances. We'd like to be able to compare them to marine records of global glaciation and learn more about how ice sheets and climate are linked together. More information... Evaluating spatial models of erosion Erosion takes place through many processes: landsliding, soil creep, river incision -- and it's hard to know which processes are most active at a particular place and time. How we account for all these processes affects the erosion rate that we infer from a Be-10 measurement. Andy Gendaszek is learning how such a measurement can yield not only the erosion rate, but also an assessment of which erosional processes are most important, and how we can best represent them. More information (PDF presentation)   River erosion in the Pacific Northwest The rivers of the Pacific Northwest drain an area of active tectonics, active erosion, and active disturbance by natural and industrial causes. Is the erosion that these rivers accomplish keeping pace with tectonic uplift? Have landscape disturbances since settlement significantly increased erosion rates? Undergraduate geology/music major Nathaniel Thompson can tell you. More information (large PDF poster)    Exposure frequency of the Antarctic landscape What have "average" glacial conditions in West Antarctica been in the past two million years? Cosmogenic isotopes in bedrock surfaces record a complex history of limited exposure and repeated cover by the West Antarctic Ice Sheet. Recent measurements from the Ford Ranges, made with support from Lawrence Livermore National Laboratory and NSF, constrain this long-term history. More information ... Deglaciation of Antarctica We use cosmogenic-isotope dating of glacially transported rocks, or "glacial erratics," to determine when, and how fast, the Antarctic ice sheet receded after the last ice age 10,000-20,000 years ago. We have worked with the Australian Antarctic Program in the Prince Charles Mountains and at several coastal sites in East Antarctica. Recently, we have been working with the US Antarctic Program on the deglaciation of the Ford Ranges, on the Marie Byrd Land coast in West Antarctica. View some results from the Ford Ranges ...    Timing of the Last Glacial Maximum worldwide We and others associated with our lab have exposure-age dates on glacial deposits from all over the world -- North America, Oceania, Antarctica, Europe, and Asia. We're interested in how best we can compare these data to tell us about the sequencing of major climate changes and ice sheet advances. More information... Pleistocene erosion rate changes, Utah How does climate change affect rates of surface processes and the direction of landscape evolution? In theory, cosmogenic-isotope measurements on sedimentary sequences should tell us about past changes in erosion rates that can be compared to climate records. Greg Balco is working in Fisher Valley, Utah currently to determine if there's any truth to this. Preprint of the paper...   Deeply weathered continental surfaces The ancient, low-relief surfaces of continental interiors are the result of prolonged weathering over geologic time, and many are thought to be "fossilized landscapes," essentially unchanged for hundreds of millions of years. John Stone and collaborators are using cosmogenic-isotope and other geochronological techniques to determine when these surfaces were created and how stable they actually are. More information...    Glacial-lake megafloods, Russian Altai In this project we're attempting to determine the age of giant flood-related bedforms (e.g., giant gravel dunes at left) along the Chuya and Katun Rivers in the Russian Altai Mountains. These were formed during outburst floods from large ice-dammed lakes and were some of the largest floods ever recorded. More information... Calibration of isotope production rates You can't divide P into N and get T if you have no clue what P is. We're involved in a number of calibration experiments designed to better determine the rate at which cosmogenic isotopes are produced, both by primary cosmic radiation and by secondary particles originating in the Earth's atmosphere and crust. More information...