OVER THE EDGE: MAPPING QUATERNARY GEOLOGY DEPOSITS BEYOND THE GLACIAL MARGIN

With the assistance of LiDAR data, surficial geology mapping work under the auspices of the Great Lakes Geologic Mapping Coalition has led to the development of new mapping capabilities. Recent mapping studies conducted by the Ohio Geological Survey included using LiDAR and ArcGIS to develop methods for mapping glacial geology in three dimensions as well as setting a new standard for detailed mapping of karst features. Availability of LiDAR data also makes it possible to map the landscape in greater detail, including the results of Quaternary weathering processes that produced deposits in unglaciated territory. With the use of the slope derivative from LiDAR data, much can be delineated that was not previously observable. Current surficial mapping at the glacial margin in the Rainsboro and Bainbridge 1:24,000 quadrangles required definition of new mapping units for Ohio due to observations associated with LiDAR coverage. Thick colluvial deposits are evident in the chaotic slope data at the base of otherwise smoothly sloped bedrock hills. Landslide scarps, chutes, and toe slope deposits are quite evident and can be mapped also. Although printed 1:24,000 topographic maps still have many uses, LiDAR data provides a new set of analytical tools, and LiDAR data is rapidly becoming the primary choice for creating base maps for detailed surficial mapping.