ARTICLE I.— SILURIAN FOSSILS FROM THE KOKOMO, 

 WEST UNION, AND ALGER HORIZONS OF INDIANA, 

 OHIO AND KENTUCKY. 



By Aug. F. Foerste. 



In Ohio, the Silurian section was divided by Professor 

 Orton into the following lithological units, named in descend- 

 ing order : 



Hillsboro sandstone. 

 Cedarville limestone. 

 Springfield limestone. 

 West Union limestone. 

 Niagara shale. 

 Dayton limestone. 

 Clinton limestone. 



In east-central Kentucky, the following horizons can be 

 recognized, also named in descending order: 



( Estill clay 

 Alger member j Waco limestone 



Crab Orchard formation I ^ Lulbegrud clay 



_ ,. T- , 1 , ^ Oldham limestone 



Indian Fields member - ^, , , 



( Plum creek clay 



Clinton formation Brassfield limestone. 



In this classification, the Brassfield limestone is the south- 

 ern continuation of the strata which were identified in Ohio, 

 by Professor Orton, as Clinton. The Oldham limestone 

 apparently is equivalent to the Dayton limestone. The Plum 

 creek clay is a local deposit and can not be traced with con- 

 fidence beyond east-central Kentucky. This is true also of 

 the Waco limestone, so that the northward extension of the 

 Alger member of the Crab Orchard formation consists only of 

 clay and clay shale uninterrupted by limestones, and corre- 



JotTR. Gin. Soc. Nat. Hist. Vol. XXI, No. 1. Printed September, 1909 



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