606 INDEX TO THE STRATIGRAPHY OF NORTH AMERICA. 



been regarded as the eastward continuation of ttie Tuscaloosa formation (Upper Cretaceous), 

 by the Georgia and Alabama geologists." 



In the Carolinas these beds are separated from the overlying Black Creek formation by an 

 unconformity. Likewise an unconformity separates them from the overlying Eutaw forma- 

 tion in the Chattahoochee and Alabama river regions in Georgia and Alabama. Geographi- 

 cally the belt in which the deposits occur is separated from the Cretaceous occurrences to the 

 northward in Virginia by an overlap of Miocene beds. However, in all their physical characters 

 they bear a close resemblance to the Patuxent formation, which forms the basal division of the 

 Potomac group in Virginia and Maryland. On account of this physical similarity and because 

 of their supposed buried connection with the Virginia Patuxent, the application of the name 

 Patuxent has been extended to include these North Carohna arkosic beds. The apparent con- 

 tinuity of the North Carohna beds with the similar deposits to the south would, in the absence 

 of laiown unconformities, seem to necessitate the adoption of the name Patuxent for all the 

 beds in question in South Carohna, Georgia, and Alabama, unless biologic evidence indicating 

 the incorrectness of tliis interpretation is forthcoming. With one exception no organic remains 

 have been found in these arkosic beds south of the Virginia line. A few poorly preserved plant 

 remains have been collected recently from an exposure in a bluff of Tallapoosa River at Old 

 Fort Decatur, in Macon County, Ala. These were submitted to E. W. Berry, who expressed 

 the opinion that the beds containing them are of Lower Cretaceous age. The meager paleon- 

 tologic evidence thus afforded tends to confirm conclusions which Mr. Berry and the writer 

 had previously reached, based on physical criteria alone. Unfortunately the poorly preserved 

 condition of the leaves renders it difficult to determine satisfactorily the relation of the forma- 

 tion to the Patuxent formation of Virginia and ^Maryland. However, in Mr. Berry's opinion, 

 the presence of large numbers of leaves, apparently dicotyledons, most of which are too poorly 

 preserved to permit their specific or even generic determination, seems to justify doubt as to their 

 being as old as the Patuxent formation, in which similar questionably identified dicotyledons 

 are very sparingly represented. 



I-J 13-14. EASTERN NEW MEXICO, OKLAHOMA, AND SOUTHERN KANSAS. 



Portions of the Comanche series appear along the canyons which descend from 

 the Tertiary of the High Plains to the " Red Beds." There are unconformities both 

 above and below these incomplete sections, which constitute the northwestern 

 occurrences of the Comanche series. Hill^^ describes in detail sections observed 

 in Kansas, Oklahoma, and New Mexico, with comparative faunal lists, and under 

 the title "Plains section" he summarizes the strata as follows: 



Plains Tertiary. 

 "Dakota" sandstone. 

 Belvidere beds: 



(6) Blue and black shale with fossils [the Kiowa shale of Cragin "'^,"i'], 



(a) Cheyenne sandstone grading upward into 6. 

 "Red beds." 



The fauna consists largely of typical Washita species with a few that range 

 down into the Fredericksburg. 



I-K 13. NEW MEXICO, COLORADO, AND WYOMING. 



The Morrison formation of Wyoming and Colorado was formerly referred 

 without question to the Jurassic on the evidence of its large vertebrate fauna. More 

 recent studies of this fauna by Scott, Williston, and others favor its reference to the 

 Lower Cretaceous, but this assignment of age is not yet unanimously accepted, and 



a Langdon, D. W., Variations in Cretaceous and Tertiary strata of Alabama: Bull. Geol. Soc. America, vol. 2, 

 1890, pp. 587-606. Veatch, Otto, Second report on the clays of Georgia: Bull. Geol. Survey Georgia, No. 18, 1909, 

 pp. 82-106. 



