182 DESCEIPTIVE GEOLOGY. 



emerges into the meadows south of Hantz Peak, a white quartzite having 

 a northwest strike, with a dip to the eastward of 35° to 40°, has been 

 considered a continuation of that found on the north shoulder of Hantz 

 Peak, and hence to represent the Dakota Cretaceous. Higher up the stream 

 are some reddish sandstones, and, at the very head of the stream, on the 

 divide betAveen these waters and those of the Little Snake River, is found 

 a body of about 100 feet in thickness of blue clay-shales, which resemble 

 those of the Colorado Cretaceous. In the meadows below, in the cuttings 

 made by streams in the Quaternary deposits, are occasional outcrops of 

 sandstones and shales, too inconsiderable, however, to be indicated. On 

 Milky Fork, so named on account of the amount of fine white sands sus- 

 pended in its waters, which come from the sandstones on Whitehead Peak, 

 is shown a reddish sandstone, which probably corresponds to that seen in 

 the canon above mentioned. These sandstones, however, do not resemble 

 those of the Triassic. In the stream-cuts, at the forks of Elk River, are 

 found a considerable body of clay-shales and some blue limy shales con- 

 taining Ostrea and Inoceramus. These stand almost perpendicularly, with 

 a strike about north and south, to the east of which is a conformable bed 

 of metamorphosed white sandstone. The exposures are, however, altogether 

 too inconsiderable to afford any definite outlines of structure, though the 

 beds have exadently been compressed into sharp folds against the Archaean 

 mass, which is exposed on the other side of the strealm. Following down 

 Elk River, for some 10 miles below the forks, the Archaean beds rise steeply 

 on the east side, showing occasional outcrops on the west side of the river, 

 while in the low, gently-sloping gravel benches of the western slopes are 

 found frequent exposures of the blue and drab shales of the Colorado Cre- 

 taceous, generally dipping at a gentle angle to the westward, and, in some 

 cases, overlaid by a grayish-white, fine-grained sandstone. 



In the low saddle to the northeast of the Sugar Loaf was found an ex- 

 posure of a dark, compact, rather siliceous limestone, evidently forming the 

 crest of a gentle anticlinal fold. The round hill to the westward, enclosed 

 within the bend of the river, is composed of yellowish and white, coarse 

 sandstones, dipping 10° to 15° to the eastward, overlying the limestone 

 formation, while at the base of the Sugar Loaf were found the same blue 



