SEPARATION OF CARBONIFEROUS AND RED BEDS. 113 



Tliougli the beds in Nebraska that were referred by Mr. Meek to the 

 Permian are now considered by him as of npper Coal Measure age, it may 

 be well to consider their character in this connection. The Sub-Carbonifer- 

 ous in all the Missouri region consists of massive limestone deposits, while 

 the upper portions of the Carboniferous, the upper Coal Measures, are com- 

 posed of more or less thin bedded, alternating deposits of shale, limestones, 

 sandstones, bituminous shales, and, as far west as eastern Nebraska, thin 

 coals. Such deposits are called " oscillatory," as indicating unsteady and 

 repeated changes in the circumstances of their formation. The alternating 

 series of the Hills differs conspicuously in the character of its component 

 beds, but corresponds in the matter of oscillation. 



With the very fragmentary and unsatisfactory evidence that is here 

 brought to bear upon the question of the relation of these upper beds of 

 the Carboniferous, we can arrive at no more definite conclusion tlian to say 

 that they are with little doubt Carboniferous ; tliat they are probably upper 

 Carboniferous, and that they may possibly by future investigation be 

 established as Permian, 



In the position I have assigned to the upper limit of the Carboniferous 

 I differ somewhat from Professor AVinchell and Dr. Hayden. The former 

 places it higher, including the purple limestone which interrupts the red 

 clays, and the latter places it below the alternating series. 



When Dr. Hayden visited the Hills in 1857, he labored under the 

 disadvantage that always pertains to a rapid reconnaissance, and to this we 

 must lay his low estimate of the dimensions of the Carboniferous. His 

 error in this regard was very natural, as the portion of the formation trav- 

 ersed by him is greatly thinned by denudation. He divided the Carbon- 

 iferous into two portions, as follows: " G. Hard, more or less gritty, 

 yellowish and whiteish limestone, containing Productus, Spirifera, Euom- 

 phaliis, etc., passing down into a light yellowish calcareous gj'it, altogether 

 50 feet;" and, passing downward, "H Very hard, reddish-gray limestone, 

 containing Si/ringopora, Proditdits, Terehratula, etc., * * * 50 feet."* 



His "G" is our No. 3; his "H" is our No. 2; our smallest measure- 

 ment gave them a total of 300 feet. The sandstones, etc., which we have 



* Tiaii.s. Am. Phil. Soc, 18t)'2. Geology of the Upper Missouri, Hayden. 

 8 B H 



