white.] FOSSILS OF THE CACHE A LA POUDEE. 175 



made, and consequently the aggregate thickness of them is not known. 

 This thickness, however, is estimated to he ahont 250 feet between 

 Marck's farm and a point about four miles above Eaton's farm. 



At the exposures here referred to the following list of fossils was col- 

 lected, all belonging to the extreme upper portion of the Cretaceous 

 series beneath the Laramie Group. A part of them also characterize 

 the highest known Cretaceous strata beneath the Judith Elver Group 

 in the Upper Missouri River region, as shown by Meek and Hayden, 

 but the relations of those fossils in this respect will be discussed in con- 

 nection with those collected at Fossil Creek, Little Thompson Creek, 

 the mouth of the Saint Trains, &c, because the strata exposed at these 

 localities all belong to one natural group. 



LIST OF THE FOSSILS COLLECTED FROM CRETACEOUS STRATA IN THE 

 VALLEY OF THE CACHE 1 LA POUDRE, FROM FIVE TO TWELVE 

 MILES WEST OF GREELEY, COLORADO. 



1. Fragments of fossil icood. 



2. Fteria (Oxytoma) nebrascana Evans & Shumard. 



3. Nucula cancellata Meek & Hayden. 



4. Xucnla plant marginata Meek & Hayden. 



5. Taneredia americana Meek & Hayden. 

 G. TenieUa humilis Meek & Hayden. 



7. Cardium speciosum Meek & Hayden. 



8. Tellina scitula Meek & Hayden. 



0. Mactra (Cymbopliora) formosa Meek & Hayden. 



10. Mactra {Cymbopliora) alto, Meek & Hayden. 



11. Dentalium graeile Hall & Meek. 



12. Cylichna scitirfa Meek & Hayden. 



13. Lunatia moreauensis Meek & Hayden. 



14. Anchura, ? 



15. Fasciolaria (Piestoclieilus) culbertsoni Meek & Hayden. 

 1G. Flacenticeras lenticulare Owen sp. 



Leaving the valley of the Cache a la Poudre at a point about four 

 miles west of Aaron Eaton's farm, I went more directly westward toward 

 the mountains. Search was made in this region for the line of junction, 

 or plane of demarkation between these Upper Cretaceous strata and the 

 base of the Laramie Group. In consequence of the great prevalence of 

 the debris of the plains, which has already been referred to, I v was not 

 successful in this search, although it is quite evident that the lower strata 

 of the Laramie Group occupy the upper part of the slope of the valley 

 side, as well as the higher lands of the region on both sides of the valley. 

 Higley's coal-mine, which has been already mentioned, is opened in 

 Laramie strata in the upper part of the long, low, sloping, opposite 

 valley-side, and its position is thus shown to be not far above these Cre- 

 taceous strata, and consequently near the base of the Laramie Group. 

 But this subject will be taken up again on a subsequent page. 



Proceeding westward after leaving the valley of the Cache a la Poudre, 

 I found no exposures of rock until I reached Eossil Creek, about two 

 miles east of the base of the foot-hills of the Eocky Mountains. Along 

 a ridge having the local name of "Fossil Ridge," which runs southward 

 from this creek three or four miles parallel with the foot-hills, there are 

 considerable exposures of coarse sandstones containing fossils that 

 characterize the upper series of Cretaceous strata, known in the Upper 

 Missouri Eiver region as the Fox Hills and Fort Pierre Groups. From 



