Appreciate these last answers. I wrote in response to James Williams and
GACinMass this morning but the message seems to have gone to never-never
land. And their comments were funny. Some others weren't.

I plan to use rock but first I think I will have to use some concrete block
under the liner. And also some carpeting and underliner. Shale is very
sharp. The concrete block will help distribute the weight of the stones I
plan to use.

Groundhog shale, as I understand it, is a combination of clay and shale.
The shale is broken up in fairly small pieces. I don't know why they call
it groundhog shale. We do have a lot of ground hogs although what that
might have to do with anything, who knows? I never heard of it before
moving to this area either. Never saw such rotten soil.

A mattock is sort of a combination heavy duty hoe and pickaxe. Think of a
pickaxe. Both ends of the blade are pointed. On a mattock, only one end is
pointed. The other is, as I said, a heavy duty hoe with a very thick blade.
You can grub out brush and even small trees with it. We need them around
here.

If the darned thing ever gets finished, I'll let you know.