HOMOTAXIAL EQUIVALENTS OF THE PERMIAN 323 



"Upper Coal Measures" along the Missouri River, which may 

 be regarded as the standard section, have been lately carefully 

 correlated. 



The recent work has been sufficient to give us a good idea of 

 the general character of the deposits regarded as Permian, the 

 stratigraphical successidn in the different parts of the province, 

 the range of many species of fossils, and an outline of the main 

 subdivisions that it will be useful to recognize. 



Character of deposits. — The beds of the Continental Interior 

 basin that have been considered as Permian, or Permo-Carbonif- 

 erous and Permian, consist of two heavy shales, separated by 

 thick limestones. The total thickness in Kansas is probably 

 about 2000 feet ; in Texas perhaps double this figure. 



The lower beds are almost wholly made up of argillaceous 

 and sandy shales, yellow, brown, green, and blue in color, and 

 brown shaly sandstones. Occasionally occur thin, rather impure 

 limestone bands, that carry abundant fossils. Near the bottom 

 of the formation are some workable coals, associated with which 

 is a characteristic flora. 



The median number is composed largely of gray and buff 

 limestones, often in thick layers, shaly limestones, and calca- 

 reous shales. The heavy limestones contain more or less chert 

 in nodules and discontinuous bands. Abundant fossils are 

 represented. 



The upper part consists principally of gray, variegated, and 

 red shales, and shaly limestones. Gypsum and salt deposits 

 occur abundantly. Fossils occur only vzxy sparingly. 



In the main, the deposits indicate shallow waters, in strong 

 contrast to the thalassic conditions that prevailed previously in 

 the same regions. The sediments were laid down largely in 

 closed basins, which finally become altogether dry. 



General geological section. — In Kansas the general succession, 

 as made out by Prosser and Cragin, is about as follows : 



