70 



GEOLOGICAL FORMATIONS 



the buff arenaceous limestone to be water-worn and weathered ; 

 and directly upon the eroded rock rests 20 feet of brecciated 

 limestone. Whether or not this can be regarded as a portion 

 of an ancient land surface, older than the Saint Louis lime- 

 stone, depends partly upon the results of further investigation, 

 and partly upon the final decision as to the origin of the brec- 

 ciated rock. Gordon, who has recently given special atten- 

 tion, is inclined to regard arenaceous member as the base of 

 the Saint Louis. 



At Hall's typical locality it is manifest that the Warsaw 

 beds are properly the superior portion of the Keokuk lime- 



Fig. 3. Base of Saint Louis Limestone at Keokuk 



Stone. This inference is directly derivable from the faunal and 

 stratigraphical features, and in a less marked degree from the 

 lithological nature of the deposits. The layers passing under 

 this name reported from other localities are now known to 

 have various relationships with the overlying and underlying 

 strata. Alleged faunal peculiarities have usually been the 

 chief grounds for considering the Warsaw as a distinct sub- 

 division of the Lower Carboniferous. Most writers on the 

 subject have united the beds under discussion with the Saint 

 Louis; a few with the Keokuk. This difference of opinion 



