488 SAMUEL WEIDMAN 



elusion that certain chert boulders mentioned by Taff in folded Car- 

 boniferous shales near TaKhina, Oklahoma, had been shaped by 

 earth movements and not by glacial action. The writer has seen 

 these chert fragments in the folded and faulted shale at Talihina 

 where they reveal abundant evidence of earth movements and agrees 

 fully with Woodward's interpretation of their origin. It should 

 also be stated that Taff fully recognized that certain marks on boul- 

 ders described by him resembled slickensided surfaces. 



There are, nevertheless, certain formations of Carboniferous 

 age in the Ouachita Mountains of eastern Oklahoma containing a 

 mixture of various kinds of large boulders derived from different 

 sources, the origin of which as stated by Taff is difficult to explain, 

 except in some manner through the agency of ice, probably the work 

 of icebergs. If the evidence presented by the writer in the Arbuckle 

 and the Wichita mountain areas indicates Carboniferous glaciation, 

 the erratic boulders described by Taff would seem to fall naturally 

 into the same category. 



W. H. TwenhofeP in 191 7 in a paper entitled " Granite Boulders 

 ( ?) in the Pennsylvanian Strata of Kansas," described numerous 

 large boulders, mainly of granite porphyry within the area occupied 

 by formations of Pennsylvanian age near Rose, Woodson County, 

 Kansas. Many of the boulders are as much as four feet in diameter, 

 the largest being seven feet in diameter, and they appear to be unlike 

 the granite boulders of the Pleistocene drift, the southern limit of 

 which Ues about 75 miles to the north. The boulders are now 

 exposed on Pennsylvanian strata and while their correlation could 

 not be fully determined, Twenhofel is inclined, for various reasons, 

 to consider that they are of Pennsylvanian rather than of Tertiary 

 or Pleistocene age, and that the boulders reached their present posi- 

 tion through the agency of ice, either glacial or floating, more prob- 

 ably the latter. The possibility that the Rose boulders may be 

 correlated with the Squantum tillite near Boston, Massachusetts, 

 described by Sayles^ is suggested by Twenhofel. 



There are, therefore, in the rocks of Carboniferous age, some 

 distance from but within the general region of the Arbuckle and the 



^ Am. Jour, of Science, Vol. XLITI (1917), pp. 363-80. 



^ Bull. Mus. Comp. Zobl., Vol. LVI, No. 2, Geol. Series, Vol. X (1914), pp. 141-75. 



