DIFFERENT PROVINCES OF NORTH AMERICA IN LATE PALEOZOIC TIME 83 



Pennsylvania!! sediments in all of the Ozarks, however, indicates that the sea 

 may have retreated again in a comparatively short time, probably before the 

 end of the Des Moines epoch. If the Warrensburg and Moberly channels came 

 into existence late in the Pleasanton epoch, as seems probable, a relative uplift 

 of the Ozark took place at that time. Moreover, the differences in the sediments 

 laid down in Missouri and Illinois during the Missouri epoch, so far as known 

 from strata still intact, point toward the presence of a land-mass between the two 

 areas during that interval. Some of the sands deposited in parts of the Missouri 

 epoch are also most easily explained by postulating a land-mass in southern 

 Missouri. The overlap of Des Moines strata toward the west and the probable 

 derivation of some early Des Moines sediments from an Ozark land-mass, on 

 the other hand, seem to show that the Ozarks were above sea until late in the 

 Cherokee epoch. * * * 



"SEDIMENTATION DURING MISSOURI EPOCH. 



"The Missouri group seems to have been deposited under conditions which 

 alternated between those of quiet waters, which permitted the growth of marine 

 invertebrates but excluded clastic sediments to a large degree, and those of 

 unsettled and disturbed waters in which sandstones and shales were deposited. 

 From time to time the more unsettled conditions changed during short intervals 

 in which lenticular coal or limestone beds were formed. While quiet waters 

 prevailed and calcareous materials were conspicuous among the sediments, condi- 

 tions were unfavorable for extensive plant growth. Even at other times coal- 

 forming plants succeeded in establishing themselves only for relatively short 

 intervals and, with one or two exceptions, in comparatively small swamps. The 

 intervals of limestone deposition, on the whole, grew shorter as time progressed. 



"One of the notable features of the deposition during the Missouri epoch was 

 the repetition of an alternating succession of limestones and thin shales with 

 thicker shales and sandstones. Almost exactly similar conditions of sedimenta- 

 tion appear to have recurred intermittently over wide areas. There is a striking 

 similarity in the Plattsburg and Stanton, Oread, and Deer Creek limestones and 

 to a less degree in the Lecompton, Topeka, and Howard, and the Tarkio and 

 cap-rock limestone of the Xyman coal. In each case the sections show only 

 minor variations from the following succession: 



1. Limestone, flaggy; a thin bed (at top). 5. Limestone, dark gray; even-bedded; I or 2 feet. 



2. Shale, drab; a few feet. 6. Shale, drab. 



3. Limestone, gray, thin-bedded; a thick bed. 7. Limestone, blue (at base). 



4. Shale, black, slaty. 



" In the Plattsburg and Stanton, Oread, and Deer Creek members this succes- 

 sion is typically shown. In the other cases mentioned the place of the dark-gray, 

 even-bedded limestone (5) seems to be taken in some areas by coal, and the 

 limestone (3) is much thinner. 



"The clastic members have certain resemblances, which, however, are not 

 nearly so striking as those just mentioned. Most of them contain sandstones 

 that vary in apparent stratigraphic position within short distances, and include 

 limestones that do not maintain uniform thicknesses. 



"DEFORMATIONS. 



"From the beginning to the end of Pennsylvanian time in Missouri earth 

 movements in the region now occupied by the series were relatively slow, simple, 



