OHIO FOSSILS 



CHAPTER 7. MISSISSIPPIAN FOSSILS 



Collecting Localities 



GENERAL . The Mississippian rocks of Ohio are exposed in a wide belt from the Ohio 

 River in the south to the vicinity of Lake Erie in the north where the outcrops continue east- 

 ward to the Pennsylvania line (see map, fig. 8). In the extreme northwestern part of the state, 

 in Defiance, Williams, and Fulton counties, is a smaller area of Mississippian rocks separ- 

 ated from the larger area to the east. 



In the Lower Missippian Waverly group we find the oldest large body of sandstones and 

 shales cropping out in Ohio. The lower part of the Waverly consists of shales, in some places 

 hard to distinguish from the Devonian shales. Silt and sandstone layers increase as we go 

 upward in the column until they make up most of the rock of the Upper Waverly. Silts tones, 

 sandstones, and shales all contain abundant fossils from place to place. 



The Maxville limestone is found only in patches as it was- deposited on an irregular sur- 

 face and much of it was eroded before the later sediments were laid down. The Maxville car- 

 ries a fauna small in number of species but abundant in individuals of remarkably good pres- 

 ervation. See Morse (1911) for description of the species. 



NORTHEASTERN OHIO . The lower part of the Mississippian section in this area yields 

 brachiopods sparingly throughout but there are large concentrations of fossils in some beds. 

 The Cuyahoga formation contains a varied fauna which includes well preserved brachiopods, 

 pelecypods, gastropods, and a few trilobites. 



EAST-CENTRAL OHIO. In the area centering around Licking County, the Cuyahoga and 

 Logan formations have proved particularly prolific in fossils: Both the silty and shaly beds of 

 these formations yield fossils in abundance but the better preserved ones are those from the 

 shales. The area around Granville and Newark was intensively explored by many workers, 

 especially C. L. Herrick (1887) who published extensive lists of fossils from that area. In some 

 beds in Licking County, the whole surface of a bed may be covered with brachiopod shells 

 (Rhipidomellas and productids). In the shales, pelecypods are commonly found, along with 

 rarer cephalopods and conularids. Some of the best preserved specimens are from iron 

 concretions which abound in some of the shales. 



SOUTH -CENTRAL OHIO . In this area, the formations mentioned for northern and east- 

 central Ohio are also present and yield fossils in about the same numbers, but here they are 

 overlain, in some localities, by patches of Maxville limestone which is abundantly fossilifer- 

 ous -,see Lamborn (1945). Thirty-six species have been listed from the Maxville. 



A famous collecting locality of former days was the ledge of Byer sandstone in the Ohio 

 River, called the Sciotoville bar. It has yielded thousands of brachiopods, pelecypods, gas- 

 tropods, and other fossils. Many of these are filled with the mineral sphalerite (zinc sulphide) 

 or sometimes with galena (lead sulphide) or with calcite (calcium carbonate) in which delicate 

 structures of the interior of the shell are preserved. The bar is now covered by deep water 

 behind one of the dams which provide water for navigation. 



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