Oh yeah! That WAS a glacial lakeshore.

I am smacking myself in the forehead for not realizing I was exploring exactly the kind of glacial lakeshore early-man site that I wanted to find in Nevada. Better late than never.

On the other hand, I am patting myself heartily on the back for picking a place to explore that has perhaps the highest concentration of lithic debris in the whole valley. The dark brown crescent at the southern end of the chert outcrop is darker than any other of the patches. Having been there on foot, I can tell you what these different features are:

The amazing thing (I'll write about this more on Rock Piles) is that the darker patches are a heat map. I am now looking at aerials of the whole valley (called Hidden Valley on the topo map) and not only is my hill the best place to look (the darkest) I can also see other specific places I should have gone here and there - because they also have dark brown patches. How cool is that!