Hilltop Site Revisited

Recently I returned to the hilltop site I described previously (10/24/2012).  This site has several propped boulders, in varying stages of completion.
Here is a completed propped boulder.

The other side shows a sharp edge along  the bottom, indicating the stone was worked.  There are three supporting stones under it.

There is no reason a farmer would do this.  Below is a propped boulder  in progress.  Once the large fragment was removed, a support stone could be placed under the boulder, and more stone from the lower edge chipped away. It looks like someone was going to take a  slab off the top, also.  Maybe this was done later than the removal of stone from the bottom.

Here is  a close-up of the partially completed boulder I showed previously (10/24/2012)

Notice the large flake of stone on the ground to the right.  It looks like it was knocked out of the side of the boulder directly above it.
Here is another propped boulder shown previously.

This has a striking tall and narrow shape from the other side.

The sides are smooth and flat, as stone has been removed.  I have never seen an upright boulder like this anywhere else.  It is about 10 feet tall.
Near some of these boulders is this large rock with a strange "chair" shape. When I swept away the leaves, I found the "seat" is flat.   This was probably not used in food production, but may have been used in making and edging tools.  There might be tools and rock chips scattered around it.

 This site is also surrounded by farm walls and platform cairns surmounted with carefully stacked rocks.

I think this site shows the historical progression of Indian quarrying.  First  the Indians built these propped and oddly shaped boulders for their own reasons. After  the white man came, they used their quarrying skills to break up boulders into squarish stones and build walls. Of course, it is impossible to be know exactly how the site was altered over time.
      In less than two weeks, somebody added a tongue to the site guardian!