338 ROLLIN T. CHAMBERLIN 



Orange River Colony, and in the Transvaal, the Dwyka conglom- 

 erate rests unconformably upon the older rocks, generally upon the 

 strata of the Cape System/ 



The age of the Cape System is still somewhat uncertain; the 

 middle member (Bokkeveld series) is of Devonian age, but the age 

 of the upper member (Witteberg series) is more in doubt, as these 

 beds have as yet yielded no remains of animals, and only rather 

 poor specimens of plants. While httle value can be placed upon 

 the determinations, it is to be noted that all the genera found occur 

 in the Carboniferous rocks of Europe.^ Hatch and Corstorphine 

 are also inclined to correlate the Witteberg series with the Carbo- 

 niferous of the Northern Hemisphere.^ The Ecca series is of 

 Permo-Carboniferous age, but until more is known about the age 

 of the strata involved in the folding this widespread break in 

 South Africa cannot well be correlated with movements elsewhere. 

 But it would be most natural to suppose that the glaciation (repre- 

 sented by the Permo-Carboniferous Dwyka conglomerate) followed 

 closely upon the deformation. 



In North America movements which appear to be contempo- 

 raneous with the Hercynian folding of Europe at the close of the 

 Westphalian have been recognized at a number of points. Very 

 pronounced movements affected portions of Oklahoma. The 

 Arbuckle Mountains, which had suffered Culmide folding, were 

 again subjected to strong folding before the close of the Pennsyl- 

 vanian. Taff states that this deformation commenced near the 

 beginning of Upper Carboniferous time and ended before its 

 close.'' Hutchison describes the major portion of the present 

 structure of the region of the Arbuckle and Criner Hills as formed 

 in early mid-Carboniferous times. ^ The date of the folding, while 

 occurring some time within the Pennsylvanian period, cannot as 



' F. H. Hatch and G. S. Corstorphine, op. cit., pp. 335-38; also Plate I, opposite 

 P-33- 



^ A. W. Rogers and A. L. DuToit, An Introduction to the Geology of Cape Colony, 

 2d ed. (1909), pp. 159-60. 



3 Hatch and Corstorphine, op. cit., p. 344. 



ij. A. Taff, "Geology of the Arbuckle and Wichita Mountains in Indian Terri- 

 tory and Oklahoma," Prof. Paper ji, U.S. Geol. Survey (1904), p. 38. 



s L. L. Hutchison, Bull. 2, Oklahoma Geol. Survey (1911), p. 7. 



