GEOLOGICAL REPORT. 



The Upper Cretaceous brown-coal formation which is 

 the district of the Rocky Mountains, on the Upper Pla 

 Brvan's Pass, ami which I have mentioned already above, 

 development, only slightly modified by local influences, es] 

 and is composed of an alternation of white, gray, yellowi 



layers of brown-coal niostlv from I! to "24 inches wide. 



Taking all these evidences Together, very little doubt 

 Lignite formation on Deer Creek should not be of the sain 



from their color and the mai 

 with those underlying the Mi 

 pare section II). They exh 

 formation, to the point wher 

 the north to the south side, i 

 laceous shales of drab, greei 

 and some coarse sandstones 

 and hornblende rock. The 

 where they are more numerc 

 seams of rounded masses, e> 



of clay of about the same thickness, a 



nd thu 



s the b; 



ire hlutf 







appearance, only interrupted by lieav 



ier str 



ata of 



sandsto 





Fheir st 



nearly horizontal, and they thus appea 



r to be 



uncont 



ormabh 



'TotlU: 



I lignite i 



seem to dip slightly to the east, so tha 



t, travi 



Bling d 



own the 



) rivei 



•, we gr 



to higher strata, The whole thickness 



; of the formation doi 



_^s not 



seem to 



200 to 300 feet, but could not be estin 



aated c 



•loselv. 



It for 



ma fcal 



de-hills 



ous sides, and I- did not observe any f 



ossik 



The 



upper c 



.r easi 



ern poi 



arenaceous: the hurt-color prevails in 



it, and 



some 



of the 



sandsi 



tones ai 



glomeratic, probably on account of th 



e prox 



imity c 



f the higher l 





Near Fort Laramie, below the can 



on of the Plat 



te, a moi 



•e rece 



nt Terti 



is extensively developed in the riverw 



alley 1 



md in 



the adje 



aning 



hills, w 



observed also close below the fort, and 



has b( 



jen mei 



utioned 





tion II. 



made up of finely arenaceous strata, wl 



licli ar 



e light- 



■gray or 



whiti- 



di, from 



of calcareous substance. Some strata 



are c< 



wser 



calcare< 



»us or 



siliceou 



partly concretionary and irregular, like 



the ro. 



^ksoftheAsh-: 



Hollow formal 



are generally more friable, and do not f 



orm th 



e same 



tine see 



nery. 



The sc 



strata contain, at manv points, numerous irre 



gular i 



•oot-like 



whin 



i bodies. 



sand and carbonate of lime, or silicate < 



)f calci 



a, whit 



h I have 



• also : 



mention 



