This is terrestrial shale (boys and girls this means that it is an ancient soil). It is nifty because I have only seen soil up to this point which had only been deposited in a marine setting... If you look closely at the pic, and expand it, you can see all the differing colors of the shale. Usually in Ohio and Kentucky the shale is a bluish to grey tint. This purple was actually red at one time and there are other colors in as well. The many colorations are caused from the roots of long sinced decayed trees. So this is also an indicator that it is Mississippian age rock... WHEW!
-S.I.B.-