THE ItEGION OF COAL CREEK PEAK. U3 



From a point a tew hundi'ed feel north of Coal Creek to the north- 

 eastern slope of tlic peak, although there is great obscurity from the pres- 

 ence of debris, it is doubtful it any but the higher formations are present. 

 It is furthermore impossible to determine the manner in which the strata 

 take up the conditions that prevail to the north and northeast of the peak. 



At the northeastern base of the peak is an outcrop of Red Beds, 

 forming a low cliff just south and west of the small stream there flowing. 

 The strata to the south of the stream dip gently south; wesl of the stream, 

 west; near the eastern edge of the outcrop, east, here indicating beneath the 

 debris a union with the beds of regular dip to the north of the creek; there 

 is, in short, in the Trias of this locality, a small anticlinal fold. Passing 

 directly up the slopes of the peak several hundred feet above the outcrop 

 of Trias, a small patch of Dakota is seen adhering to the side of the granite 

 mass. I hi following around the face of the mountain, east, other fragmen- 

 tary remains of the Dakota are found, at successively lower levels, until 

 the slightly projecting crest of the main north-and-south body of the forma- 

 tion is reached. Beneath the Dakota outcrops on the northern and 

 northeastern sides are also found fragments of the Jura mottled sand- 

 stones, together with occasional traces of the gray and purple shales of 

 the same formation. No dips or strikes appear in any of the frag- 

 mentary outcrops, unless in the Dakota, where there are indications of 

 gentle inclination to the west. From this, and from the relative position 

 of the formations found on the side of the mountain, it seems probable 

 that the anticlinal fold first seen in the Trias must also include some of 

 the younger formations — to the top of the Dakota at least. The axis of 

 the fold has a trend to the west of north, at an acute angle with that 

 of the range, and in the same direction as the axes of the echelon folds to 

 the north and south. The axis dips rapidly to the south, and it is doubt- 

 ful if the anticline extends much beyond the eastern base of the mountain. 



GEOLOGICAL DEVELOPMENT OF Till: \l:EA. 



The foregoing structural conditions indicate for their development a 

 peculiar combination of events. In the first place, there apparently existed 

 in the floor of the Triassic sea in this locality an important Archean 



MON XXVII 8 



