This is very interesting.

What strikes me is sometimes having a deep sense of timelessness - that is (for myself) having some non-cerebral comprehension of an enduring quality of human yearning. This can be so powerful as to become an altered state. I have absolutely no idea of how much of my mind I share with my pre-historic forbears but I completely understand the desire to create something enduring, to mark the passing of one's life and of those that mattered to you.

I have had three or four intensely wierd (drug free) experiences at prehistoric places - two of which were in the Cambrians where the sites concerned are very small. But they were also at times when I was feeling intensely wierd so it's difficult to tell where the causal line lies between person and place.....then add in drugs..