CHAPTER XIX 

 THE MISSISSIPPIAN (EARLY CARBONIFEROUS) PERIOD 



The time from the close of the Devonian period to the end of 

 the Paleozoic era was formerly regarded as the Carboniferous period. 

 But this interval is now divided into two or three divisions, each 

 with the rank of a period. If three divisions are made (as here), 

 the first is the Mis sis sip plan (Subcarboniferous, Lower Carbonifer- 

 ous) period. It represents a time of widespread submergence of 

 the North American continent, and was brought to a close by wide- 

 spread emergence. The second, the Pennsyhanian (Carboniferous, 

 Coal Measures, Upper Carboniferous] period represents a time 

 when the area between the Appalachian Mountains and the looth 

 meridian maintained a halting attitude, being now slightly above 

 sea-level and now slightly below it. West of the Great Plains, sub- 

 mergence was rather general, as during the preceding period. The 

 third division of the old Carboniferous period is the Permian, a 

 time of notable crustal deformation, general aridity, and, during part 

 of the period at least, low temperature. 



FORMATIONS AND PHYSICAL HISTORY 



The following subdivisions of the Mississippian system are 

 recognized in the regions indicated: 



Mississippi River States Pennsylvania 



4. Chester (or Kaskaskia) series (including Cypress 



sandstone below, and Chester beds above). 2. Mauch Chunk 



3. St. Louis series (including Salem limestone below 



and St. Louis and St. Genevieve limestones 



above). 

 2. Osage or Augusta (including the Burlington 



and Keokuk limestones, and Warsaw shale). i. Pocono 

 i. Kinderhook (or Chouteau) 



East of the Great Plains 



In the early part of the Mississippian period, coarse sediments 

 (sands and gravels, now a part of the Pocono formation) were gather- 

 ing along the western border of Appalachia, while in the' central 

 part of the Mississippi basin the sediments of this stage (Kinder- 



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