6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 69 



Many geologists believe that the red color of sedimentary rocks 

 denotes cold, arid climate, and the suggestion has been made that 

 the " Red Beds " of the Rocky Mountain region may denote a glacial 

 epoch. No indication of the presence of glaciers has yet been found 

 in these beds, but they seem to be of about the same age as the 

 extensive glacial deposits in India, Australia, and South Africa. 1 

 If it is true that glacial epochs follow periods of general diastrophism 

 and are caused by changes in oceanic and atmospheric circulation, 

 brought about by earth movements, it seems reasonable to associate 

 these red rocks with glacial conditions and to correlate them with the 

 beds of Permian age in other parts of the world, some of which are 

 known to be of glacial origin. Furthermore, it seems reasonable to 

 assign the elevation of the ancient Rocky Mountains to the period 

 of general diastrophism usually called the Appalachian Revolution, 

 which wrought world-wide changes in climate, geography, and 

 biology. 



In this connection it seems not out of place to suggest a line of 

 study that is well worth following, namely, the determination of 

 the date of this ancient uplift of the Rocky Mountains and its rela- 

 tion to this revolution. 



Conspicuous evidences of diastrophism are found between Penn- 

 sylvanian and Permian, in the restricted area occupied by the Arbuckle 

 Mountains in southern Oklahoma, where the older rocks were up- 

 lifted, sharply folded, and eroded so that the beds of Permian age 

 lie across the eroded edges of several thousand feet of strata which 

 range in age from Ordovician to Pennsylvanian. In several places 

 in the Rocky Mountain region an unconformity separates rocks of 

 unquestioned Pennsylvanian age from overlying rocks which may 

 be Permian. However, in some places the Pennsylvanian age of 

 some of the " Red Beds " has never been questioned. Although the 

 indications are that this uplift affected the whole Rocky Mountain 

 region and resulted in a general unconformity between these two 

 series of rocks, 2 the problem has not yet been worked out. 



Although much remains to be learned about the time of this uplift 

 and its results, it seems obvious that the sea of Pennsylvanian time 

 was expelled from the Southern Rocky Mountain region and that 

 mountains were raised in its place previous to the time of the 

 principal red-bed accumulation. For our present purpose it is of 

 secondary importance whether these red rocks are of Pennsylvanian 



1 Chamberlin, T. C, and Salisbury, R. D., Textbook III, pp. 632-636, 1906. 



2 Lee, W. T., Geol. Soc. America, Bull., vol. 5, P- 169, 1917- 



