THE BUILDING OF THE COLORADO ROCKIES 151 



uplifted range. More exact determination of the age of this 

 diastrophism must await closer correlation of these lower Red 

 Beds. But one may well wonder whether this ancestral Rocky 

 Mountain building, which seems to correspond in time with a 

 prominent period of folding in the Arbuckle Mountains of Okla- 

 homa, may not prove to have been closely related to the mid- 

 Pennsylvanian Hercynian orogenic disturbance recognized by 

 Baker and Bowman in the Trans-Pecos region of Texas. ^ On the 

 other hand, the Appalachian diastrophism would seem to have come 

 after a portion at least of the Permian, if the Dunkard beds included 

 in the Appalachian folded series are correctly referred, as is 

 commonly done, to the Permian. 



It is hot sufhciently clearly recognized by geologists that the 

 diastrophism marking the closing stages of the Paleozoic was 

 a double diastrophism,^ comprising an essentially world-wide 

 Hercynian orogenic disturbance — the Westphalo-Carbonide move- 

 ment between the Westphalian and the Stephanian — and a more 

 local Appalachian disturbance, the Permo-Carbonide movement 

 which came after a portion at least of the Permian. It was the 

 earlier, or Westphalo-Carbonide, movement that inaugurated those 

 profound climatic changes which are recorded in widespread evi- 

 dences of vigorous glaciation within the tropics, in the astonishingly 

 wide prevalence of Red Beds the world over, and which are reflected 

 in turn in great changes in life, and which, in view of the dominat- 

 ing character of these changes and their great significance from 

 many standpoints, may perhaps not unfittingly be chosen as the 

 dividing line between the Paleozoic and the Mesozoic. 



Lee states that in few places in the Rocky Mountains can a 

 line of separation be drawn between the Permian and Triassic 

 rocks, while there is a much greater break in sedimentation between 

 the Pennsylvanian hmestone and the Permian Red Beds.^ During 

 the later Pennsylvanian and Permian periods detritus from the 



' C. L. Baker and W. F. Bowman, "Geologic Exploration of the Southern Front 

 Range of Trans-Pecos, Texas," Univ. of Texas, Bull. No. IJ53 (1917), PP- 107-12. 



* Rollin T. Chamberlin, "Periodicity of Paleozoic Orogenic Movements," Jotir. 

 GeoL, XXII (1914), 334-45- 



3 Willis T. Lee, op. cit., p. 7. 



