That devil's tower is a trip. Made up of hexagonal columns of some precision, like an organism. Same with the Giant's Causeway, I think it's called, with the same hexagons of stone.

There's a State park called Petit Jean that I used to visit a lot, there's a natural sidewalk on one of the trails made of this 'box work' or carpet rock as they call it, there's a photo at this link: http://www.encyclopediaofarkansas.net/encyclopedia/media-detail.aspx?mediaID=7875