CORRELATION OF CARBONIFEROUS ROCKS 343 



tion of Kansas ; while a massive Fusidina limestone west of 

 Auburn, Nemaha county, was regarded as the Cottonwood lime- 

 stone. 



It remained, however, to trace these formations from the 

 Kansas River Valley into Nebraska in order to fully demonstrate 

 the accuracy of the above correlations. Fortunately the recent 

 areal work of the University Geological Survey of Kansas has 

 nearly completed this part of the proof. As the classification 

 of the formations of southeastern Nebraska has an important 

 bearing upon the Permian question of Nebraska and Kansas a 

 synopsis of the results of this work will be of interest. During 

 the summer of 1898, Mr. J. W. Beede of the University of Kan- 

 sas, traced the Burlingame limestone from the Kansas River, 



upper part of the Upper Coal series, and include limestones, sandstones, and shales, 

 amounting to about 180 feet in thickness" {ibid., p. 379). Dr. Keyes gives the thick- 

 ness of the Atchison shales as 500 feet on the Missouri River, and describes the stage 

 as composed mainly of shales with a stratum of coal near the base {op. cit., p. 310). 

 In Kansas the Wabaunsee formation is composed of massive limestones separated by 

 calcareous, argillaceous, and arenaceous shales. (See the writer's description of the 

 formation in Jour. Geol., Vol. Ill, pp. 688-697.) 



The only other reference to the Atchison county group in Professor Broadhead's 

 papers, known to the writer, is in his article on the " Coal Measures of Missouri," 

 where he revised and quoted the section from the 1872 report, with this introductory 

 sentence: "The following is a vertical section of the Coal Measures below the 

 Atchison county beds" (Mo. Geol. Surv., Vol. VIII, 1895, P- 3 00 )- On page 377 is a 

 brief description of the highest rocks in the state, which are said to occur in "Atchi- 

 son and the northern part of Holt county," but as far as a formation name is 

 concerned, they are put under what is termed "Group A," and there is no mention of 

 Atchison county group or beds. 



In view of the above facts it does not appear to the writer, in the first place, that 

 the name "Atchison county group," used by Professor Broadhead in 1873, was ever 

 defined as the name of a formation ; and, secondly, that the name "Atchison shales," 

 proposed by Dr. Keyes in 1899, is not entitled to be substituted for the Wabaunsee 

 formation described by Prosser in 1895. 



The writer finds that the above is essentially the opinion of other geologists 

 familiar with questions of this character. It is clearly stated in the following letter 

 from one of the members of the International Commission on Stratigraphic classification: 

 " I do not possibly see how the use of the term in the manner described could be 

 regarded as a formation name. Many such indefinite uses of local names are found 

 scattered everywhere through geological literature, and if we are to go back in every 

 instance to such a usage, few I fear of our formation names would stand. The name 

 to my mind must be applied to a definite series of deposits with clearly defined limits, 

 if it is to have any formational significance." 



