Back in 2006 when news of newly discovered pyramids was reported in Bosnia, I remember checking out the tiny photograph of the angular, foliage covered hills, then shrugging my shoulders and moving on. It seems that amateur archaeologists have continued the investigation of these hills, and have posted the results on Flickr.
They are really lovely photographs of more (pseudo)archaeologist-made archaeology–that is, naturally occurring geological formations dug in such a way to suggest “real” archaeological remains. The thing is, I am also a geology nerd (if you couldn’t tell by my photographs of the Giant’s Causeway in Ireland) and while I deplore the needless destruction of the sandstone layers of an ancient lake and the later actual archaeological sites on top of the formation, it’s pretty neat to see the layers in section.
If you’re so inclined, check out what other archaeologists had to say about the pyramids, or check out the edit log from the wikipedia entry–it’s pretty instructive from a cultural heritage/knowledge construction point of view.
Colleen Morgan 
I too am a geology nerd and (belatedly) totally agree with you – that’s rock – about as natural as it gets.
Thanks for saving me the bother of checking this out.
I agree that these excavations appear to be more natural than man-made, but just as in Yonaguni, there is always the possibility that ancient man either took advantage of natural geology or was inspired to imitate it. Even lear from it and expand on such inspiration.Many of the ancient constructions are imitations of natural structures. Mountains, caves and other geological formations. Inspiration from nature is at the heart of all of mankind’s early creations.
…the clay of the Pyramids in tucume also seems natural after a period of time…same with the chinese pyramids and some old Zikkurats in Irak…
They look different on a microstratigraphic level. Also these are still natural.