slgwv's photos with the keyword: Fort Rock

And Fort Rock Valley beyond; telephoto view looking east from the rim above Hole in the Ground. Oregon, USA. Fort Rock is a tuff ring around another eruptive center, now an Oregon state park. It evidently never actually was a "fort"--it's named from the resemblance.

Wave-cut bench on south side. Fort Rock is a broken ring of tuff deposits from an eruptive center that was submerged during the Pleistocene. Hence there are lots of surf-erosion features such as this.