This Major Research Instrumentation (MRI) Program grant supports acquisition of an high resolution x-ray fluorescence (XRF) core scanner equipped with a color CCD line scanning camera for paleolimnological and paleoclimatological investigations at the Large Lakes Observatory (LLO), University of Minnesota - Duluth. An Avaatech XRF Core scanner will facilitate PI and students research requiring rapid, non-destructive, high spatial resolution (~1mm) and high sensitivity determination of the concentration of major, minor and trace elements in sediment cores. The XRF scanner will offer new advances for studies of lacustrine sedimentary records of climate and environmental change with annual to decadal resolution. High resolution studies of sediments recovered from East African Rift lakes, the U.S.-Canadian Great Lakes, and large lakes within the Asian and South American continental interiors will immediately benefit. A wealth of community-accessible, long, and continuous lacustrine sedimentary records from around the world (e.g., Great Salt Lake, Bear Lake, Lake Titicaca, Lake Malawi and soon Bosumtwi) are archived at the LacCore national lake core repository in nearby Minneapolis. The LLO XRF core scanner will be made available to the larger paleolimnological community for study of these and other lake sediments. ***