Precision Cut Rocks at Puma Punka Peru

[Pimander]

You don't need aliens to have lost technology.  Someone was clearly (in my opinion) navigating the globe supposedly before the invention of the clock (therefore unable to calculate longitude).

There is some interesting info out there on the use of ultrasonics I will try to find if I get some time.

[Shasta56]

What if they communicated with the stone, and asked it to grow in those formations?   The Earth is a sentient being.

Shasta