9702643 Bierman The densely populated northeastern United States is subject to extreme hydrologic events that impact the landscape. Some of these events are meteorological; nor'easters, hurricanes, and convective thunderstorms generate rainfall of sufficiently high intensity and duration to cause property damage, ecologic disturbance, and erosion. Other events are human-induced; a century ago, the region was almost completely cleared of forest, increasing rates of runoff and erosion. The history of deforestation and reforestation is well documented; yet 200 years of data are insufficient to characterize the spatial and temporal distribution of the largest storms, those having the greatest recurrence intervals, those capable of the greatest damage, and those causing the most significant, episodic landscape change. It is our working hypothesis that in the well-forested Northeast, where infiltration rates are typically high, lacustrine and alluvial fan sedimentation occurs primarily during very intense and/or long duration storms when soil pore pressure increase sufficiently to trigger landslides and saturation overland flow. Our data indicate that sedimentation can also be triggered by deforestation, such as occurred during colonial land clearance; yet, pollen, charcoal, and macrofossil data indicate that New England has been clothed in forest continuously since 11,000 years ago. Although local erosion and sedimentation events could be triggered by tree die back, fire, or localized storms, large-scale storms seem the most reasonable explanation for regionally synchronous sedimentation events. To further my long-terms goals, understanding rates of landscape change and using research-based inquiry as a teaching tool, this proposal seek funds to collect, analyze, date and compare 30-40 Holocene sedimentary records from the Northeast (New England and New York). By comparing the ages of sedimentation events at wide-spread sites, we will determine the percentage and timing of deposit ional events that are regionally synchronous. To establish the timing of lacustrine sedimentation events, we will collect, date, and analyze cores from 15-20 "hydrologically sensitive" ponds, those with large, steep, drainage basins. To constrain ages of terrestrial sedimentation events, we will trench, describe and date deposits in 15-20 alluvial fans. We will use both data sets to map (for the past 10,000 years) the temporal and spatial distribution of sedimentation events and by analogy, the paleo-distribution of storm events capable of causing significant hillslope erosion. Not only will we publish our data through conventional channels, but we will create a dynamic Web site and interactive exhibit in the heavily used Perkins Geology Museum at UVM. The Web site will be both a data repository updated as the project progresses and a teaching tool for Earth Science education from the pre-college through the University level.
