562 JOSIAH BRIDGE 



Mississippian deposits has failed to disclose any determinable 

 Mississippian fossils. Some of the oolite is conglomeratic, con- 

 taining small angular chert pebbles, and much of it contains small 

 cavities, some rounded, others angular, which simulate the impres- 

 sion of poorly preserved fossils. Lee has suggested that this oolite 

 is the possible equivalent of the Short Creek oolite of southwestern 

 Missouri. The writer has not seen Lee's collections from the fossilif- 

 erous oolite, and his own observations have not confirmed Lee's. 

 Bowlders of siliceous oolite are abundant in the residual material 

 over a large part of this area. There are beds of it in the Jefferson 

 City formation, and some oolite bowlders have been found which 

 contain Canadian fossils. On the other hand, many of the oolite 

 bowlders are weathered and stained with iron oxide in much the 

 same manner as are the Mississippian bowlders, while others do 

 not seem to have been weathered in this manner. 



The association of the different types of bowlders seems to 

 follow no general rule. In some localities they consist exclusively 

 of sandstones, while in others chert predominates, but in nearly 

 every case examples of all the easily recognized lithologic types are 

 to be found together. 



The fossils are in most cases preserved as molds of the exterior 

 and as casts of the interior. In rare instances the shell itself, 

 together with the internal structures, has been completely silicified. 

 In many examples the molds and internal casts preserve the mark- 

 ings of the original with great fidelity, and excellent squeezes may 

 be obtained from them. Some difficulty has been experienced in 

 correlating the mold with the internal cast, for, strangely enough, 

 when one surface is well preserved, the other often is not. 



The material used in the preparation of this paper has come 

 from three sources: (1) a collection belonging to the Department 

 of Geology of the Missouri School of Mines and Metallurgy, lent 

 by Professor Cox and Professor Dake; (2) some collections be- 

 longing to the Missouri Bureau of Geology and Mines, lent by 

 Mr. Buehler; and (3) a number of collections made by the writer 

 and his friends. These were made while the writer was connected 

 with the Missouri School of Mines and are the property of that 

 institution. 



