224 REPORT UNITED STATES GEOLOGICAL SURVEY. 



descendants of their lower representatives respectively, but the local 

 facts are at least suggestive of some such connection. At any rate, 

 there seeins>to be no reason for doubt that the change of condition con- 

 sequent upon the movement that caused the unconformity brought 

 about a corresponding change in the aqueous fauna. 



Leaving the Bitter Creek district, with much that is interesting there, 

 to be noticed in the closing discussion, I now return to the Dani'orth 

 Hills, near White Eiver, and resume my observations, in the order of 

 my journey, where I left them to consider the Bitter Creek series. 



My journey upon leaving the Danforth Hills was by way of a canon 

 that opens into Agency Park at a point about six miles directly south of 

 the locality where I obtained the collection of Laramie fossds, and near 

 the western end of the park. 



In the sides of this canon appears the junction between the Laramie 

 and Fox Hills Groups, the character of which has already been described. 

 Following down the drainage of the callon into the park, we come upon 

 the Colorado Group, and upon the banks of White Biver we find the 

 strata of the Dakota Group also. ~No fossils were found in the latter, 

 but fragments of Inoceramus deformis with Ostra congesta were found in 

 the former. About a mile up from the mouth of the canon I obtained, 

 from a layer of the Fox Hills Group, within 100 feet of its top, the fossils 

 of the following list. Near by, in the same canon-side, 200 feet above 

 the layer just mentioned (100 feet above the base of the Laramie Group), 

 I collected fragments of some of the same species of fossils, both vegetable 

 and hi vertebrate, that were found to characterize the Laramie strata in the 

 Mils five miles to the northward, which have already been discussed. The 

 fact has already been stated, that although the plane of division between 

 the Laramie and Fox Hills Groups in this neighborhood is quite plainly 

 recognizable, it is marked by no unconformity, nor by any such abrupt 

 change in the character of the deposits as would prove a break to have 

 taken place in the continuity of sedimentation. Thus we find a purely 

 marine condition indicated for the origin of the stratum affording the 

 fossils of the following list, and a brackish-water condition for that of all 

 the strata which are more than 100 or 200 feet above it, which condition 

 continued unchanged through a deposition of strata nearly or quite 4,000 

 feet in thickness : 



LIST OF CRETACEOUS FQSSrLS FROM A CANON SIX MILES NORTHWEST 

 FROM WHITE RIVER INDIAN AGENCY, NORTHWESTERN COLORADO. 



1. Inoceramus bambini Morton. 



2. Cardium speciosum Meek & Hayden. 



3. Mactra ( Cymbophora) alta Meek & Hayden. 



4. Anisomyon centrale Meek. 



5. Actceon woosteri White % 



6. Baculites ovatus Say. 



NOTES ON THE CRETACEOUS FOSSILS FROM NEAR WHITE RIVER INDIAN 



AGENCY. 



1. Inoceramus bambini Morton. 



Examples of this species were found to be quite abundant at some 

 places in the fossiliferous stratum in which they were found. They seem 

 to agree well with the typical forms of the species. 



