55. GASPORT Dolomite 

Gasport Dolomite is a geological formation of Early Silurian age found in the Lockport Group of western New York and Ontario. It is characterized by a lower member (Gothic Hill) of crinoidal-rich dolograinstone and an upper member (Pekin) of argillaceous dolomicrite that contains bioherms. It represents a period of reef-building, and its fossils include brachiopods, corals, and bryozoans.