266 T. W. STANTON DAKOTA SANDSTONE PROBLEMS 



acteristics, this faunule ought to be Lower Cretaceous, but I have not 

 been able to make specific identifications of any forms characteristic of 

 the Lower Cretaceous or the Comanche series." In fact, no genera were 

 identified ; but, on account of the recognition of a marine deposit beneath 

 the Dakota and distinct from the Morrison, it was classified tentatively 

 as Lower Cretaceous. In beds of this same unit near Lander, Wyoming, 

 Williston 14 has recorded the occurrence of crocodile and shark teeth, 

 among which he identified four species "with species obtained from the 

 Mentor beds of the Lower Cretaceous of Kansas." Williston believed that 

 the bed containing the fish teeth, together with the underlying sandstone 

 and conglomerate, belonged in the Morrison formation, which he was dis- 

 cussing under the term "Atlantosaurus beds." Most of the Kansas fish 

 teeth with which comparisons were made came from the "Greenleaf sand- 

 stone/' which was described as overlying the Kiowa shale, but some came 

 from the unquestioned Kiowa. Scylliorhinus, the only genus mentioned 

 in Williston's paper, is recorded from the "Greenleaf sandstone" only. 

 Species based on teeth of sharks and crocodiles, as usually identified, have 

 a considerable stratigraphic range. 



Attention is called to the possibility or even the probability that the 

 Dakota sandstone of this section is the same as the Newcastle sandstone 

 of the Black Hills section, and that the underlying shale and possibly 

 some lower beds are also of Dakota age. 



A section in southeastern Wyoming, on Horse Creek, north of Cheyenne 

 (number 11 of the chart), is almost equidistant from the Lander area 

 and the Black Hills. The diagram is somewhat generalized from my own 

 field-notes, from the section published by Darton in the Laramie-Sherman 

 folio, and from a section measured by W. T. Lee which he has kindly 

 permitted me to use. In this section, a short distance beneath the Mowry 

 shale, there is a sandstone 25 to 50 feet thick, comparable in character and 

 position with the Newcastle sandstone of the Black Hills section and, 

 like it, treated by Darton as a member in the Graneros shale. Beneath 

 the sandstone there are dark shales and thin-bedded sandstones with a 

 thickness of 150 feet which contain fish bones and scales and marine 

 invertebrates identified as 



Pteria sp., related to P. gastrodes Meek. 

 Inoceramus sp., related to /. lahiatus Schlotheim. 

 Turrit cllaf sp. 



The comparisons are -with species of the Colorado group, but they might 

 as well have been witb Plena saUnaensis White and Inoceramus coman- 



l * Journal of Geology, vol. 13, 1905, pp. 347, 348. 



