WHITE.] BIJOU CREEK. 191 



From the valley of Bijou Creek my investiji^ation led me southwest- 

 ward to Cherry Creek Plateau, during which I passed over the higher 

 strata of the Laramie Group, wliich come in the series between those that 

 i found exposed near Bijou Station and the sandstones of the Monu- 

 ment Creek Group, that constitute the plateau. I foinid no fossils of 

 any kind in these higher Laramie strata except silicified wood, which in 

 some i)laces was quite plentiful. It is possible that certain layers in this 

 portion of the Laramie Group contain invertebrate fossils, but the whole 

 series in tliis region above the horizon of the fossiliferous layers of the 

 Crow Creek and. Bijou Creek sections is apparently destitute of inver- 

 tebrate remains. 



The whole thickness of Laramie strata which I thus passed over, from 

 the upi^ermost layers of the Fox Hills Groux;) m the valley of South 

 Platte liiver to the base of the Monument Creek Group on Cherry Creek 

 Plateau, is estimated at about 1,800 feet. So far as I could discover, 

 only about the lower 200 or 250 feet of this series is known to contain 

 invertebrate fossils ; and the lower 700 or 800 feet apx)ears also to con- 

 tain all the coal of the Laramie Group in this region. 



Exhibiting to some ranchmen whom I met in the valley of Bijou Creek 

 the fossils I had collected there, they informed me that they had found 

 similar ones some twenty-five or thirty miles directly to the eastward ; 

 and, as already stated, Melania ivyomingensis is similarly reported to occur 

 on Horse Tail Creek, upon the south side of the South Platte, and about 

 seventy-five miles eastward ixom Greeley. These reports are not offered 

 as conclusive evitlence of the existence of Laramie strata at those two 

 localities, but taken in connection with other known facts, we are at least 

 warranted in accei)ting them as provisional evidence. The other facts 

 referred to are the known easterly dip of all the strata near the mount- 

 ains and their almost level extension out ui^on the plains 5 and the known 

 presence of characteristic Laramie strata on the line of the Kansas Pa- 

 cific Eailroad, two hundred miles east of Denver, as already recorded on 

 previous pages. In short there seems to be no reason to doubt that im- 

 mediately beneath the debris of the plains, the strata of the Laramie 

 Group occupy, besides other considerable areas to the northward and 

 southward, the whole broad space between the South Platte and Arkan- 

 sas Elvers (except narrow spaces immediately adjacent to the two rivers 

 respectively, where the strata of the Fox Hills Group appear to come 

 up to the surface), extending eastward from the base of the Eocky Moun- 

 tains quite within the limits of Western Kansas. 



Sedimentation seems where I crossed the jilace of division to have 

 been continued without interruption from the Laramie Group, which is 

 mainly a brackish- water, but in part a fresh- water deposit, to the Mon- 

 ument Creek Group, which is probably a jiurely fresh- water deposit, al- 

 though no invertebrate fossils have been found in it. This last-named 

 deposit is probably equivalent with the White Eiver Tertiary, a forma- 

 tion that has already been mentioned as occupying a large area of the 

 l^lains north of the South Platte, but from my present limited personal 

 knowledge I regard it as joossibly equivalent with either the Wasatch, 

 Green Eiver, or Bridger Group, which have their fidl development west 

 of the mountains. It is possible that the upper 800 feet of what I have 

 referred to the Laramie Group ought also to be included vnih the Monu- 

 ment Creek sandstones, but as 1 discovered no i^laue of demarkation 

 betAveen the grouj)s where I examined them I prefer to leave it with the 

 Laramie Group. 



Following these statements it is proper that I should make some 

 reference to the reported discovery of marine Tertiary fossils by Pro- 

 fessor Powell in the valley of Bijou Creek, as reported upon by myself in 



