Graphic shows the section of the USGS quad digitized to create the 1947 Surface.  Below it is the area with hatcher lines enlarged on the 1869 map graphic for comparison.  The graphic was traced in CorelDraw and converted to a DXF file then imported into ArcInfo and registed using the coordinates of the traced features.      It is impossible to tell what this ravine looked like exactly in 1869 but by using the 1947 surface generated from these contours and comparing it with the photographic record there is evidence that there has been considerable erosion in this area and could vary well have been as steep as it is depicted in the 1869 surface.