154 DESCRIPTIVE GEOLOGY. 



group. A section across the ridge, on the west side of the Platte, near the 

 river, two miles south of Fort Steele, shows, in the lower 2,000 feet, princi- 

 pally beds of massive sandstone, 50 to 100 feet in thickness, with a few 

 shaly seams at the base, overlaid by a thickness of about 1,500 feet of more 

 thinly-bedded sandstones, in thickness varying from 5 to 10 and 15 feet, 

 with interlaminated shales, sometimes bituminous, and two or three thin 

 seams of coal. In the valley south of the ridge, the upper beds run into 

 more reddish, iron-stained sandstones, which have been considered to rep- 

 resent a remnant of the lower beds of the Laramie group, in the trough of 

 the synclinal. The whole thickness of the Fox Hill beds, which we esti- 

 mate at between 3,000 and 4,000 feet in this region, is not exposed in this 

 ridge, the lower beds being concealed beneath the Quaternary of the valley. 

 Some of these beds can be seen on the low hills just west of Fort Steele, 

 where there are indications of a narrow anticlinal fold having an east and 

 west axis parallel to this ridge. ^^ 



About 4 miles east of Fort Steele, in the railway gap, which cuts a high, 

 prominent ridge, dipping about 16° to 20°, the following section was taken 

 in descending series: 



Feet. 



1. Heavy-bedded white sandstones 1, 000 



2. White and buff sandstones 200 



3. White blocked sandstone 50 



4. Yellow sandstone 25 



5. Shale beds '. 75 



6. Yellow sandstone 50 



7. Brown sandstones 750 



8. Brownish-red sandstone ." ~\ 



9. Sandy shales, with impressions of small bivalves \ 150 



10. Coarse sandy shales 3 



2j 300 



The North Platte Eiver cuts tlirough the nearly horizontal rocks of the 

 synclinal basin, exposing along its bluffs many good, but limited sections, 

 showing between 400 and 500 feet of strata. In general, they do not differ 

 greatly from those already given. The following section, made near where 



