[1] During the Mississippian, the sea gradually transgressed over the current United States Mid-west, depositing significant limestone sequences across the region.

[9] Within this large-scale sea level rise, there were many smaller cycles of transgression and regression, which are expressed in stratigraphic facies packages within the larger framework of the formation.

[5] The formation is marine in origin, and bedding planes, cross-stratification, and fossil assemblages indicate that it was deposited in high-energy, relatively shallow water.

[8] As the Pahasapa is a marine limestone, the fossils it contains are primarily brachiopods and scattered corals,[1] along with some crinoid plates, gastropods, and bryozoans.

[10] In the sections of the Pahasapa that have been dolomitized, many of the fossils have been destroyed due to recrystallization of the calcium carbonate, and those that remain have a distinctive "sugary" appearance.