292 KANSAS UNIVERSITY QUARTERLY. 



occurred leaving the strata already formed in an inclined position, 

 so that the new formations will not be conformable with them. 

 The other condition accepted universally as a sufficient basis for 

 making a division or sub-division in stratigraphy is a positive varia- 

 tion of any character in the flora or fauna of the formations con- 

 cerned. There may be grounds for difference of opinion, or differ- 

 ence in custom regarding the degree of variation which should obtain, 

 but all admit that if the change is sufficiently great a division of the 

 formation should be made, either with or without unconformity. 



The Coal Measures of Kansas are 2750 feet thick, and cover an 

 area of approximately 20,000 square miles. It would seem desirable, 

 therefore, for the sake of convenience to subdivide them into two or 

 more groups. But when a section of country has been studied in suffi- 

 cient detail to trace the different great classes of formations across the 

 whole area, and to determine their limits vertically, as has been done 

 for the Kansas Coal Measures through the assistance of the numer- 

 ous deep wells which have recently been drilled in our state, it 

 becomes possible to make many sub-divisions to which local geo- 

 graphic names can be applied, thereby in great measure limiting the 

 convenience which may be derived from other kinds of sub-divisions. 

 It is doubtful whether any real convenience will arise by making any 

 division of our Coal Measures other than those already made and to 

 which local geographic names have been assigned, for it is now 

 possible to speak exactly with reference to any portion whatever of 

 our Coal Measures anywhere in the state by a proper use of the terms 

 already introduced. 



It is the concerted opinion of the different individuals who have 

 been engaged with the writer in field work that the Kansas Coal 

 Measures'should be divided into two divisions, which may be desig- 

 nated as the Lower and the Upper. Careful search failed to discover 

 any considerable unconformity anywhere between the Cherokee 

 shales and the Cottonwood Falls limestone, yet, as has already been 

 pointed out, slight unconformities exist everywhere. The upper- 

 most members of the Coal Measures are quite different from those 

 situated at the base, but the transitions of all physical properties 

 seem to be gradual rather than abrupt. This gradual change is 

 shared by the coal itself. The variations in lithologic characters are 

 mere repetitions from limestone to shale and sandstones, and then 

 back to limestone again. It is apparent to every member of the Sur- 

 vey that unless the change from shale to limestone, or limestone to 

 shale would warrant a division, nothing in the line of physical proper- 

 ties throughout the whole Coal Measures could be used as a basis. 

 But when we turn to the side of paleontology we are not so wholly 



