Niagaran Reefs of the Great Lakes Area

Abstract

The controversial issue as to whether or not certain structures in the Niagaran of the Great Lakes region are true reefs is reviewed. Reefs are defined in terms of fundamental biologic potentials of the organisms responsible for them rather than in terms of the present-day appearance of the structures. These potentials are the ability to erect rigid topographic structures by frame-building, sediment-retention and binding, and to create a wave-resistant structure. These have been the basic properties of reef-building biota throughout all time. Organisms potentially capable of erecting the Niagaran structures are shown to have been present. Evidence of their performance capacity is presented. The biologic affinities of the common builders, combining frame-building and sediment-binding abilities, remain to be determined. Stromatoporoids performed these functions in some cases. The character of the niche-dwelling assemblage is reviewed in terms of environmental relations and potential source material for bioc...