COOPER LIMESTONE. 13 



tion outcrops intermittently for several miles but in places was 

 entirely removed before the deposition of the Mississippian 

 rocks. 



The original extent of the Cooper is problematical. It did 

 not reach far east of Boone County, as in that direction the 

 Mineola occupies the same horizon and the two formations con- 

 tain only two identified species in common. Southward from 

 Boone, Moniteau, Morgan and Pettis counties, only older rocks 

 are exposed. West of Morgan County and south of Pettis no 

 indication of Cooper limestone occurs. It may extend westward 

 from Pettis County under the younger rocks and as it is thickest 

 in its westernmost outcrops it seems probable that it is present 

 westward. The Cooper seas may have connected northward 

 with the earliest middle Devonian seas of Iowa. They extended 

 as far eastward as Spalding in Ralls County and probably to the 

 Mississippi River. The paleontologic data are too meager for 

 positive conclusions and the paleogeographic map in Plate F, 

 figure a, is only a suggestion. If the sea in which the Cooper was 

 deposited had been connected with the seas of eastern Missouri 

 and Illinois the fossils should indicate it. The thickening of the 

 Cooper westward suggests sea connection in that direction. As 

 it does not occur in outcrops south of Pettis County and has not 

 been found in Iowa, the western connection must have been 

 narrow. 



The Cooper is nonconformable on the Jefferson City over 

 most of its extent in central Missouri though in several places it 

 rests on St. Peter sandstone. In northeastern Missouri it is 

 disconformable on the Kimmswick and Maquoketa. 



In central Missouri the Callaway limestone is disconformable 

 on it in small areas, the Sylamore sandstone is nonconformable 

 on it over most of its extent, and the Chouteau limestone lies 

 on it where the Sylamore is absent. In northeastern Missouri it 

 is overlain disconformably by Louisiana limestone and Grassy 

 Creek shale. 



Paleontology. — The Cooper faunas are meager and the 

 species are not diagnostic. Some places have given promise of 

 furnishing abundant faunas from abundant fragments of fossils of 

 various kinds but the fossils have not been found. Pleurotomaria 

 providencis Broadhead seems to be the most widely distributed 

 species in Missouri. It occurs in western Boone County and also 

 in Ralls and Marion counties. Only Favosites alpenensis 

 Winchell, Streptelasma cooperensis Branson, and Atrypa reticularis 



