256 STANTON 



sandstone (now identified with the Eagle sandstone) at the base of 

 that group- The shales and sandstones between these two have been 

 named the Claggett formation, and the shale above the Judith River 

 has been named Bearpaw. The latter is the equivalent of the upper 

 part of the "Pierre" shale as developed at Glendive and elsewhere in 

 eastern Montana and probably includes the equivalent of at least part 

 of the Fox Hills, though the upper part of the Fox Hills is possibly 

 represented in the base of the overlying "Laramie." The succession 

 in the marine Cretaceous with Stone's measurements of the dififerent 

 formations is as follows: 



Montana group: Feet. 



Bearpaw shale 700 to 11 00 



Judith River formation 400 to 800 



Claggett formation 400 to 800 



Eagle sandstone 100 to 250 



Colorado shale 1300 



This stratigraphic succession is developed in most of the Cretaceous 

 areas in Montana west of a line drawn across the state through the 

 Pryor Mountains and the mouth of Musselshell River. For detailed 

 descriptions of these formations the reader is referred to the papers 

 cited — especially to the one by Stone for local details — but there are 

 some facts that deserve mention in this connection. 



One of these important facts is that the Judith River formation 

 with a vertebrate fauna of Trachodon, Ceratopsia, turtles, etc., occurs 

 here in unquestionable stratigraphic sequence beneath about a thous- 

 and feet of marine Cretaceous strata which in turn are overlain by 

 beds containing a related dinosaur fauna. Not only is this true, but 

 Douglass^® has recorded that the intervening Bearpaw shale [its 

 lower part] has yielded specimens of Trachodon and other land dino- 

 saurs directly associated with marine invertebrates, showing that these 

 dinosaurs inhabited the neighboring land continuously from Judith 

 River time until after the end of the Bearpaw. Brown records-^ a 

 similar discovery of a dinosaur in the upper part of the Pierre shale 

 of the Hell Creek region. 



^* Proc. Am. Philos. Soc, Vol. XLI, p. 212. Annals Carnegie Mus., Vol. 

 V, p. 276. 



"Bull. Am. Mus. Nat. Hist., Vol. XXIII, 1907, p. 826. 



