whiie.] BIJOU CEEEK. 189 



existing- upon the east valley side of Crow Creek, four or five miles above 

 its mouth. I discovered similar dunes only in the neighborhood of South 

 Platte Biver. 



The valley of Bijou Creek is merely a broad, shallow depression in 

 the surface of the plains, bordered by ill-defined valley sides from two to 

 five miles apart, the elevation of which is, perhaps, 50 feet above the level 

 of the creek. The lower ten or twelve miles of the valley is apparently 

 without any exposures of strata, but the district which it traverses is, 

 doubtless, underlaid by a greater or less thickness of the Laramie Group, 

 beneath the abundant debris of the plains. This opinion is based upon 

 the known easterly general dip of all the strata of the region, the known 

 existence of the uppermost layers of the Fox Hills Group in the valley 

 of the South Platte, ten or twelve miles west of the mouth of the creek, 

 and the existence of Laramie strata, presently to be described, in the 

 west valley-side of the creek. These exposures of Laramie strata first 

 appear opposite, and about four miles west of, the junction of Muddy 

 Creek with the Bijou, and continue southward, at intervals, some three 

 or four miles up the creek. The exposures are small and inconspicuous, 

 but I made out satisfactorily the following section in the slope of the low 

 hill or valley-side : 



Bijou Creek section. • 



Feet. 



1. Sandy soil and debris of the plains 20 



2. Ordinary light-broTm sandstone 5 



3. Sandy shales 5 



4. Shale, sandy and argillaceous, containing Corbicnla, &c - 4 



5. Similar to No. 4, containing Ostrea and Anomia 3 



6. Unexposed to the general low surface of the valley, about 15 



Although in full detail the recognized members of this section differ, 

 as we should expect them to do, from those of the Crow Creek section, 

 some 35 miles distant, yet no hesitation is felt in recognizing the precise 

 general equivalency of the two sections. This recognition is all the more 

 satisfactory because two or three of the members of each section, respect- 

 ively, are unmistakably identical, as will be seen from the following' 

 comparison : 



No. 1 of the Bijou Creek section doubtless corresponds with Nos. 1 and 

 2 of the Crow Creek section ; No. 4 of the former with No. 3 of the latter; 

 and No. 5 of the former with No. 4 of the latter. Nos. 2 and 3 of the 

 Bijou Creek section are not definitely recognized in that of Crow Creek, 

 but this is of no consequence in view of the precise agreement of the 

 fossiliferous members of the section, which are of far more importance 

 than the others. The material composing No. 1 of the Bijou Creek sec- 

 tion is too uniform in all this region to need comparison or special 

 description. The sandstone of No. 2 differs in no respect from the ordi- 

 nary sandstones of the Laramie Group that are found elsewhere. No 

 fossils were found in it. No. 3 is not separable lithologicaily from No. 4, 

 beneath it, and they are treated as separate members only because I 

 found no fossils in No. 3, while No. 4 is quite fossiliferous, containing at 

 least six species that are identical with those of No. 3 of the Crow Creek 

 section. No. 5 contains Ostrea glabra Meek & Hayden and Anomia 

 micronema Meek in abundance, and in all respects like those of the Crow 

 Creek section; and, so far as I could discover, no other species were 

 associated with them. No trace of an equivalent of No. 5 of the Crow 

 Creek section, was found at the Bijou Creek locality. It is a fresh-water 

 deposit, and its local character in the valley of Crow Creek has already 

 been remarked upon. 



No strata were seen in situ in No. 6 of the Bijou Creek section, but at 



