660 T. W. STANTON 



The next step in the attempted correlation of the Morrison for- 

 mation with the Comanche series was the announcement by Lee, 

 at the Washington meeting of the Geological Society of America in 

 1902, that he had discovered Gryphaea corrugata Say, a characteristic 

 Comanche fossil, in the Morrison shales on the Cimarron near Gar- 

 rett, Oklahoma. Only brief abstracts of his paper, entitled "Age 

 of the Atlantosaurus Beds," have been published. 1 His conclusion 

 was that the non-marine Morrison formation is traceable laterally 

 into marine shales of the Comanche series containing fossils that 

 indicate a horizon within the Washita group, and that therefore the 

 Morrison is of that age. Darton stated that he had observed similar 

 relations on Butte Creek, southeastern Colorado, and he accepted 

 Lee's interpretation. As Darton's current field-work covers the 

 entire area from the Missouri River to the Wasatch Mountains, 

 the immediate effect of the new correlation on the mapping and 

 classification was far-reaching. In two published folios 2 of the 

 Geologic Atlas of the United States, and in Professional Paper 

 No. J2, "Geology and Underground Water Resources of the Central 

 Great Plains," 3 the Morrison formation is classified as Cretaceous 

 and the chief reason assigned in every case is essentially that it 

 "appears to be equivalent to a portion of the Comanche series in 

 northwestern Oklahoma and southeastern Colorado." 



Last June, through the courtesy of Mr. Darton, I was enabled to 

 join Mr. Lee in the field and visit with him the exposures on the 

 Purgatoire, the Cimarron, and the Canadian that he had previously 

 studied. We were accompanied by Mr. C. W. Gilmore, of the 

 U. S. National Museum, who is familiar with the dinosaurs of the 

 Morrison. We also visited Mr. Darton's locality on Butte Creek, 

 and later extended our observations as far south as Tucumcari, 

 New Mexico. 



1 Science, New Series, Vol. XVII (1903), pp. 292, 293; Geological Society of 

 America, Bulletin, Vol. XIV (1904), pp. 531, 532. Science gives a very brief account 

 of the discussion that followed the reading of the paper but the reporter completely 

 missed the point of Stanton's argument in opposition. 



2 "New Castle (Wyoming-South Dakota)," and "Edgemont (South Dakota- 

 Nebraska)." 



3 See pp. 34, 96, 102, 141, and 164. 



