Pike's Peak. I believe that it is situated at around 10,000' in a glacier carved cirque called the Bottomless Pit. The rock is more polished than the granite found in the lower elevation. The formation is actually visible from Colorado Springs. I did the route in 1985 with Rick Westbay.
Climbed down there back in the '70s with Billy Westbay and the crew. Super cool spot, just don't drink the stream water unless it is filtered. Miss Billy, he was the king of cool, I cry when I think about him....