Let’s take a look here at some of the formation.
In this next shot, you see a shot over the rocks toward the flueway and powerhouse where the waterwheel was.
If you go to the Flickr site (click the photo) you will see notes describing some of how the water-driven electric power system worked.
And no, it’s not marble, but granite. It was mistaken as marble because granite with clean water flowing over it has a bit of a reddish look like marble might have.