THE PLAINS PROVINCE 87 



[Garrison formation, Florena shales.] "The upper member of the formation 

 is composed of green, chocolate, and yellowish shales alternating with grayish lime- 

 stones, while in the Big Blue valley a bed of gypsum occurs near the base. * * *" 



" Wreford limestone. This formation is composed of limestone and chert, 

 or flint, as it is popularly termed throughout the Flint Hills region, and varies in 

 thickness from 35 to 50 feet. In general, it is composed of three strata, a cherty 

 limestone below and above, separated by a heavy limestone nearly free from 

 chert. The rock is buff color. * * * 



" Mat field shales. The formation is composed principally of variously colored 

 shales, with some shaly buff, occasionally cherty limestones, and a light-gray 

 limestone 2 feet or so in thickness, which occurs about 30 feet below its top. 

 The thickness ranges from 60 to 70 feet, and it generally forms covered slopes 

 between two massive and conspicuous flint ledges. * * *" 



" Florence flint. This formation is about 20 feet in thickness and consists 

 of very cherty limestone separated by definite layers of chert, with a band of 

 shaly or white cellular limestone near the center. * * *" 



"Fort Rihy limestone. Overlying the Florence flint is a series of massive 

 buff limestones, changing to thin-bedded and shaly strata in the upper part of 

 the formation, which have a total thickness of 40 feet or more. Near the center 

 of the formation are generally one or two massive layers, which on the weathered 

 surface form a conspicuous ledge that may be readily followed by the eye for 

 miles. * * *" 



"Doyle shales. This formation is composed of variously colored shales with 

 an occasional thin stratum of soft limestone, and has a thickness of 60 feet. 

 About 20 feet above the base is a thin, grayish limestone which often appears on 

 the surface, and at the top are yellowish shales containing a few fossils. * * *" 



" Winfield formation. This has a thickness of about 25 feet, and is composed 

 of a cherty limestone at the base with a massive concretionary one at the top, 

 the two separated by yellowish shales. * * * The chert is not so uniform in 

 occurrence as in the Wreford and Florence flints, and at some localities this 

 horizon is represented simply by a prominent light-gray limestone, nearly free 

 from chert. * * * The irregular worn upper surface of the concretionary lime- 

 stone and the appearance of many of the concretions, as though rolled in the mud 

 on the sea bottom, indicate a shallowing of the sea at this time, followed by a 

 subsidence of the sea-bottom before the deposition of the succeeding even thin- 

 bedded limestones. This change of physical condition is indicated in the fauna 

 by the nearly complete disappearance of the brachiopods and the survival of a 

 fauna composed mainly of Permian lamellibranchs. * * *" 



" Marion formation. Buff thin-bedded limestones and shales form the prin- 

 cipal part of this formation * * *. The lower part is composed of rather soft, 

 porous, thin-bedded limestones and shaly layers to shales, containing near the 

 base a considerable number of siliceous geodes and occasionally some chert. 

 Some 50 or 60 feet above the base is a buff limestone containing large numbers of 

 lamellibranchs. * * *" 



"The upper portion of the formation is composed mostly of thin buff lime- 

 stones similar to those in the lower portion, alternating with a greater thickness of 

 shales and marls, and in some localities contains beds of gypsum and salt." 

 [The top of the formation is a conglomerate, while at various localities and 

 different levels beds of gypsum of varying thickness occur.] 



