In the first photo part of the slab is on a sub-slab. In the second photo the slab is directly on the grey rock.
You can zoom in quite a lot on these photos, particularly the first one.
Regarding the 1st image in post #1811...
I can see what you are saying about a “slab on a sub-slab”, but
I have trouble understanding how that has dropped down vertically
six to ten feet from its original position, and now appears to sit on bedrock.
Unless that is just the perspective of the photo and confusing/deceptive to the eye.