242 STANTON 



tion of shales and sandstones, and especially in the upper part the 

 individual beds are apparently not continuous for such long distances 

 but change their character laterally. Some of the sandstones contain 

 very large and peculiar concretions and occasionally in the shales 

 there are thin lignitic beds but no workable coal. Associated with 

 one of the lowest lignite beds near the base of the formation is the only 

 bed of brackish-water fossils found in the section. These include 

 Ostrea glabra M. & H., Corhiila suhtrigonalis M. & H., Anomia, and 

 Corhicula cytheriformis M. & H., all of which are well-known Cre- 

 taceous species that range from the Judith River formation, or lower, 

 up to the Laramie. The dinosaurs of the Triceratops fauna have not 

 been found directly associated with the brackish-water shells in this 

 area but judging from Hatcher's map and descriptions they must 

 range down to about the same horizon.^ 



In the area drained by Lance Creek, where most of Hatcher's col- 

 lections were obtained, the lower part of the "Ceratops beds" is well 

 exposed and has the same dips of 15° to 20° as the underlying marine 

 Cretaceous, but in the higher beds the dip decreases to 5° or less and 

 the exposures are not continuous so that it has not been practicable 

 to make an accurate measurement of the thickness of the entire forma- 

 tion. Hatcher's estimate was about 3000 feet while mine was about 

 2000 feet. Although there is uncertainty about the exact thickness 

 and other minor details the general stratigraphic relations and succes- 

 sion of the whole section are perfectly simple. I cannot do better 

 than endorse the following statement quoted from Hatcher:' 



All the beds of the entire section are conformable, and bear evidence 

 of a continuous deposition, from the Fort Pierre shales up through the 

 Fox Hills sandstones and the overlying fresh-water Ceratops beds. 

 The Fort Pierre shales are not suddenly replaced by the Fox Hills 

 sandstones, but the transition is a gradual one, and it is impossible 



° The range here assigned to the dinosaurs in this section is clearly implied 

 in his statement in the 1896 paper that "it would doubtless be better to 

 restrict the limits of the Ceratops beds to those strata in which horned dino- 

 saurs occur, and to consider the underlying 400 feet of barren sandstones 

 as the equivalent of the Judith River beds." In the Ceratopsia monograph 

 the statements concerning the stratigraphic position of the various species 

 refer only to type specimens, chiefly skulls, and these were not found in collect- 

 ible condition in the lower, steeply dipping beds. 



^ Am. Jour. Sci., 3d ser.. Vol. XLV, 1893, pp. 139-140. 



