ore is comprised of fossiliferous limestone Hough, 1958).
The Quaternary deposits that lie in layers atop to bedrock in the Sleeping Bear Dunes National Lakeshore include Petoskey stones (limestone coral), igneous rocks, and sedimentary rocks. The igneous rocks and the sedimentary rocks include in their composition a variety of metallic minerals including copper, iron, and silver. The Quaternary deposits in the Sleeping Bear Dunes National Lakeshore also include the following rock types: (a) Cambrian (shale, sandstone, and conglomerate), (b) Orodovician (shale, sandstone, and dolomite), (c) Silurian (shale, dolomite, limestone, and potash), (d) Devonian (sandstone, shale, limestone, and gypsum), (e) Mississippian (shale, sandstone, conglomerate, limestone, dolomite, and gypsum), and (f) Pennsylvanian (shale and sandst
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