. Bulletin of the Geological Society of America. Geology. SILURIAN EXPOSURES IN KENTUCKY 423 r* BurKsville TTTf L'*J_.^. Bakerton Rock House ili d.\ SCJ liititii Jjo- SwQTi Bottorn^ K*^... Horse ., m the anticline where it crosses the upper waters of the Cumberland river, in southern Kentucky. While passing down the Cumberland river with Professor Arthur M. Miller, of the State College of Kentucky, we found two exposures of Silurian rocks west of Mill Springs (figures 6 and 7). About a quarter of a mile up Forbush creek a small stream enters from the north. Here 15i feet of Si
. Bulletin of the Geological Society of America. Geology. SILURIAN EXPOSURES IN KENTUCKY 423 r* BurKsville TTTf L'*J_.^. Bakerton Rock House ili d.\ SCJ liititii Jjo- SwQTi Bottorn^ K*^... Horse ., m the anticline where it crosses the upper waters of the Cumberland river, in southern Kentucky. While passing down the Cumberland river with Professor Arthur M. Miller, of the State College of Kentucky, we found two exposures of Silurian rocks west of Mill Springs (figures 6 and 7). About a quarter of a mile up Forbush creek a small stream enters from the north. Here 15i feet of Silurian limestone occur below the sandy layer at the base of the Black shale. A layer with large crinoid beads occurs 21 inches below the top of this limestone, and north of the mouth of Forbush creek, near the house of William Richardson, the same layer is found, including Whitfieldella cylindrical variety suh- quadrata. At the mouth of Little Cub creek the Ordovician is overlaid by Silu- rian limestone, with clayey shales farther up. The limestone at the base is 19 feet thick. The layer with large crinoid beads and Whit- fieldella cylindrica, variety subquad- rata, occurs 3i feet below the top of this limestone. Overlying the limestone are 2J feet of greenish clayey shale, 2 feet of clayey lime- stone, and an interval of 9 feet probably occupied entirely by greenish clayey shale. At both localities the large crinoid beads belonged originally to the Clinton. The Clinton was probably eroded, and the crinoid beads were accumulated in the residual beds. The Whitfieldella associated in the same bed is a characteristic form of the Osgood bed. It differs from the typical forms of Whitfieldella cylindrica only in its more grandrangular outline and its less sinuate anterior margin. The limestone below the Whitfieldella layer is referred to the Clinton. The limestones and clays above the crinoid bed are referred to the Osgood. The subject has been more fully studied in corresponding bed
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1890
