Research on the internet led us to the USGS web site. This assisted in the identifying of a variety of soil types and the absorption rates for each.  A topographical map was purchased from the USGS.  It has been researched at this site the absorption of different types of soil.  Sandy soils are known to have the highest absorption rate and clay soil has the lowest.  Rocks are not a type of soil but they affect the movement of water though a system.