24 



OHIO FOSSILS 



Sand from the Pennsylvanian beds is used for silica refractories, foundry, filter, ferro- 

 silicon, and silicon. They are washed clean of impurities for glass sand and potter's 

 flint. Several Pennsylvanian sandstones produce oil. These are the so-called "shallow sands" 

 of eastern Ohio. 



For many years Ohio has been the leading producer of clay and clay products. This is 

 largely because of the abundance of fire clays and clay shales of Pennsylvanian age. These 

 are used for the manufacture of brick, tile, sewer pipe, fireproof ing, and refractories 

 such as glass pots and furnace brick. 



Pennsylvanian limestones are thin, but because of their location can compete with the 

 Silurian limestones of western Ohio for use in the manufacture of Portland cement, and for 

 roads and agricultural lime. 



The Pennsylvanian seas swarmed with animals whenever living conditions were favorable. 

 Many kinds of sea animals survived from the Mississippian and many others first appeared 

 in Pennsylvanian time. 



Among the most interesting of Pennsylvanian fossils are the fusulines, a family of 

 Foraminifera exceedingly abundant in some limestones. They are small, the largest about 

 a quarter of an inch long, and shaped like rice grains (see fig. 285). The fusulines are rare 

 in the late Mississippian, abundant in the Pennsylvanian and Permian. They died out in late 

 Permian time. 



Pennsylvanian corals are about as rare as Mississippian ones and some of them have 

 peculiar characteristics. For example, one of the horn corals ( Lophophyllidium , fig. 286) 

 has a raised central axis. A few colonial corals also occur in the Pennsylvanian. 



Crinoids in great variety have been described from Pennsylvanian rocks but complete 

 specimens are rare in Ohio. The same may be said of starfishes and sea urchins. Scattered 

 plates and segments of crinoid stems and the spines of sea urchins, however, are abundant 

 in the limestone layers. 



As in the Mississippian, the most striking brachiopods are the productids which develop- 

 ed heavily -spined, large forms in the Pennsylvanian but there are also spectacular spiriferids, 

 large flat forms ( Derbyia , fig. 250), and a host of small fat brachiopods. 



Fig. 25 Stegocepbalian 



Among the pelecypods, scallop-like forms were abundant in Pennsylvanian seas. They 

 were accompanied by ancestors of the pearl-oyster ( Myalina , fig. 312), and many other less 

 spectacular kinds. 



