AMERICAN FORK CA:nON. 351 



the Ogden Qaaitzite, would probably have yielded Devonian or Sub-Car- 

 boniferous forms. 



The anticlinal structure disclosed in the American Fork section con- 

 tinues in the main ridge to the north, but the beds rise, and lower horizons 

 are successively exposed until, at Dry Canon, the granite body of the Cot- 

 tonwood district is found at the surface, a spur of which doubtless underlies 

 this whole ridge which we have been examining, and served to determine 

 its direction. The contact of the lower beds with the granite body at Dry 

 Canon has not been actually observed, but the lines of division between the 

 formations at this part of the range are based on observations from Lone 

 Peak and the position of these beds in contiguous portions of the range. 

 The limestone body north of American Fork Canon has a general eastern 

 dip in continuation of the Timpanogos Ridge, and preserves for some dis- 

 tance the same strike ; but soon the strike of all the beds bends to the north- 

 east, parallel in general to the southern line -of the Cottonwood granite bod}^. 

 At the head of Deer Creek, the first northern branch of American Fork, 

 the granite is seen to form the face of one of the spurs, while on either side 

 it is covered by the steeply-dipping quartzite beds of the Cambrian, which, 

 with a general inclination to the south away from the main body, also dip 

 east and west on either side of the spur. 



The canon of American Fork above the first bend is still in the gently- 

 inclined beds of the Wahsatch limestone, which also forms the main body 

 of the bounding ridge on the south, which stretches east from Timpanogos, 

 and separates it from Provo Valley. It soon opens out, however, into a 

 mountain-valley, with slopes obscured by soil and debris, in which it is 

 difficult to determine the exact geological horizons. A breccia-like con- 

 glomerate, formed of small, rather angular, pebbles of green and white 

 quartzites, enclosed in reddish, somewhat calcareous, matrix, which forms a 

 low hill in the midst of this valley, may correspond to a conglomerate, which 

 is found in about the middle of the Wahsatch limestone "at the head of the 

 canon. Above the second bend, the course of the stream is parallel with 

 the strike of the beds, and, as near as can be determined, runs at the base 

 of the Lower Coal-Measures. Its sides are covered for 50 or 100 feet from 



