Patterns of reef growth in the Middle Devonian Edgecliff Member of the Onondaga Formation of New York and Ontario, Canada, and their ecological significance

Abstract

Reefs of the Middle Devonian Edgecliff Member of the Onondaga Formation in New York and Ontario, Canada, contain three distinct paleocommunities: the Phaceloid Colonial Rugosan Paleocommunity, the Favositid/Crinoidal Sandstone Paleocommunity, and the rare Delicate Branching Tabulate Paleocommunity. The reefs may be classified as mounds or composite structures based on the degree of intergrowth of the rugosan and favositid paleocommunities. Composite structures may be further subdivided into mound/bank, thicket/bank, and ridge/bank structures based on the degree of development of the rugosan paleocommunity. Geographic distribution of reef types suggests that these patterns of reef growth were controlled by water depth.