3 – Ancient hot water jacuzzi, when working the sun heated the rocks, then rain from thunderstorm would run down the rocks on the right and into the pool, hot rocks then heated the water, channel at back could be opened to supply the kids paddling pool … 500ft below.

4 – Dinosaur trap, the local ancient peoples used this to trap the Mountain Dwelling Brontosauriious, which when it placed it’s
massive foot in the hole would spring the rock trap and hoist the beasty into the air. No such thing as a Mountain Dwelling Brontosauriious, see – the trap so worked they were hunted to extinction.