Green Mountain Reservoir, CO
On road to Kremmling from Steamboat Springs. Those mountains on the right are the Gore Range. The hillside on the left is shale, and the beach below is shale too! Very dark and gray looking. There is a link to a photo of the hillside showing the structure of the shale a little better. I happen to like looking at these things closely, because I find what is growing on such soils fascinating, and am looking for endemics (I didn't see any).
These photos are seconds apart, so the overcast is off to the west and the blue sky to the east: a storm coming in.