st. johx.] MESOZOIC AREAS — CRETACEOUS. 497 



Buffalo Fork Mountains, little was acquired, relative to their detail-stratig- 

 raphy iu that section. 



CEETACEOtTS. 



The work of the past season in this district did not encounter rocks 

 of the age of the Cretaceous, so far as may he judged from paleontolog- 

 ical evidence. However, to the south of our southwestern section, in 

 the contiguous district, Dr. Peale discovered beds pertaining to the Fox 

 Hills Group, charged with a distinctive fauna ; but the northern exten- 

 sion of the highlands, in which the latter Cretaceous deposits were found, 

 exhibited no certain evidence of the existence of similar horizons. In 

 the vicinity of Fort Hall, to the east and northeast, outflanking the 

 Jurassic on the west, in the disturbed belt at the intersection of the 

 Mount Putnam and the Stations IV and V displacements, occurs a 

 rather heavy series of red sandstones which may possibly be synchronous 

 with some formation of this period. But the. evidence is unsatisfactory 

 and wholly based on apparent superposition of these deposits to fossil- 

 iferous Jurassic limestones, the connection between which could not be 

 traced. On the northern flank of the Gros Ventre Bange, however, Dr. 

 Hayden discovered Cretaceous strata with characteristic fossils, Inocer cl- 

 onus, Ostrea, Pinna, Carclium, &c, a condensation of which, as well as 

 Dr. Hayden's notes on the same, is incorporated in a preceding page. 



As to the later series of formations belonging to Cenozoic time, of 

 which extensive and very varied exhibitions were found within the ter- 

 ritory of this division, their further consideration in this connection is 

 deferred until a future time, when it is hoped that, with more complete, 

 or at least more extended, observation in the unvisited quarters of the 

 district where these deposits are believed to take a conspicuous place 

 among the later sedimentary formations, some connection may be traced 

 by means of which we shall the better be able to understand the rela- 

 tions of these, perhaps, anomalous late Mesozoic and Cenozoic deposits 

 with their appearance in better-known localities in the country farther 

 south. 



32 GS 



