On the way back from a trip to nowhere

On the way back we took small roads and looked for rock piles from the car, stopping occasionally to explore a bit if an area looked promising. It seems we were doomed to fail all day. We saw a few piles that looked like good candidates for being field clearing piles: piles built at the corners of stone walls. Also we saw a couple of other examples of scooped out hollows or what looked like prayer seat configurations. I have no idea where we were on the map.

Here is one pile built into a wall corner:
A few feet along one of the walls was a curious hollow. I cannot figure this out but it looked to have been put there while building the wall.
This did not seem to be something added later to the wall or the result of some kind of damage.

Later by the road at a different place we saw something and got out to take pictures. This is one "U" shaped structure which might have been a prayer seat - although built pretty recently.
There was another a few feet away.I thought these could be kid's forts but they were a little too well made. Maybe modern day ceremonialism?

Still later on the way home, here is another pile built into the corner of two stone walls:
If you look closely behind the large pile, you can see some auxilliary piles where the smaller cobbles were collected:
So this looks good for being a field clearing pile - with no alternative motives.