504 GEOLOGY. 



resemble in a general way those of the first stage (Kinderhook) of 

 the period. Those were made while the sea was advancing on the 

 land and deepening; these while it was shoaling and retreating. Both 

 are more restricted in their distribution than the beds of the inter- 

 mediate epochs. While sedimentation was general over the central 

 Mississippi basin, there were probably changes in the relation of land 

 and water from time to time. 



In Michigan l and Ohio the sediments of this stage (Maxville, upper 

 part of Grand Rapids, see p. 500) were partly calcareous and partly 

 clastic. Farther east the accumulating beds (upper part of Mauch 

 Chunk) were clastic. 



In summation it may be said that while the Mississippian beds 

 are predominantly clastic east of the Cincinnati arch, they are pre- 

 dominantly limestone west of it, though limestone is not wanting 

 in the east, especially in the latitude of West Virginia and Maryland, 

 nor sandstone and shale in the Mississippi basin, especially in the first 

 and last epochs of the period. At many points the Mississippian 

 system carries great quantities of chert. 



The sections of the Mississippian system on pp. 557-563 give some 

 idea of its character, its range, and its relations. 2 



The Mississippian system is represented northeast of the United 

 States, where it underlies the Coal Measures of Nova Scotia. In the 

 coal field of this region 3 the Mississippian formations rest on Cam- 

 brian and pre-Cambrian terranes. The system consists of a thick 

 formation (2500 feet) of more or less conglomeratic sandstone below, 

 and of shale and limestone above. With the shale and limestone there 

 are local beds of red sandstone and gypsum. 



In the Great Plains. 



Within the area of the Great Plains, the Mississippian system is 

 known in Indian Territory 4 (part of the Caney shale, the aggregate 



1 Lane, Geol. Surv. of Michigan, Vol. VII, Pt. II, pp. 13-15, and 22d Ann. Rept., 

 U. S. Geol. Surv., Pt. III. 



2 The Mississippian (Subcarboniferous, Lower Carboniferous) is shown in many 

 of the folios of Alabama, Georgia, Tennessee, Virginia, West Virginia, Kentucky, 

 and Pennsylvania. 



3 Fletcher, Descriptive Note on the Sydney Coal Field, Cape Breton, N. S., 1900. 

 * Taff, Atoka, and Colgate folios, U. S. Geol. Surv. 



