Search:niagara period -> NIAGARA PERIOD
niagara period
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- Niagara period - - A subdivision or the American Upper Silurian system, embracing the Medina, Clinton, and Niagara epoch. The rocks of the Niagara epoch, mostly limestones, are extensively distributed, and at Niagara Falls consist of about eighty feet of shale supporting a greater thickness of limestone, which is gradually undermined by the removal of the shale. See Chart of Geology.
- Medina epoch - - A subdivision of the Niagara period in the American upper Silurian, characterized by the formations known as the Oneida conglomerate, and the Medina sandstone. See the Chart of Geology.