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Devonian

Milwaukee Cement Quarry Lithographic print from Geology of Wisconsin Survey of 1873-1877 Volume II Plate XIIIA T.C. Chamberlin, Chief Geologist.
Milwaukee Cement Quarry Lithographic print from Geology of Wisconsin Survey of 1873-1877 Volume II Plate XIIIA T.C. Chamberlin, Chief Geologist.

Devonian (WI and IL)
Devonian

417 - 354 million years ago

 

    Devonian dolomite and shale, the youngest bedrock in the state, occur along the southeastern shoreline of Lake Michigan. These rock were deposited during normal marine conditions and restricted conditions with some evaporate minerals present. Much of the rock is fossilifeous with brachiopods, bryozoans, crinoids, cephalopods, bivalves, gastropods, trilobites, fish, and plant fossils. The rock was quarried and made into cement by the Milwaukee Cement Company between 1876-1907.

Photo Gallery

Falls of the Milwaukee River at Estabrook County Park, Milwaukee, Wisconsin. The Milwaukee River flows of resistant beds of the Middle Devonian Milwaukee Foramtion. Popular spot for fisherman and fossil collectors.
© The Field Museum - CC BY-NC
Milwaukee Cement Quarry Lithographic print from Geology of Wisconsin Survey of 1873-1877 Volume II Plate XIIIA T.C. Chamberlin, Chief Geologist.
© The Field Museum - CC BY-NC