Numerous folds are present throughout the formation. The Fountain Formation is a Paleozoic sedimentary formation consisting of mostly arkosic sandstone and conglomerate. Clasts in the FF are immature, cobble to fine sand. The formation is dominated by feldspar with some quartz and muscovite. The sorting is very poor.
Numerous scours are present.
The immaturity of the clasts and the presence of the scours indicate possible alluvial fan or braided stream depositional environments. The sediments of the FF are eroded pieces of the Idaho Springs Formation. The age of the FF is approximately 300 Ma. Now, let's think about the contact between the two formations again. Notice the relatively sharp contact between the Idaho Springs and Fountain Formations.