352 DESCRIPTIVE GEOLOGY. 



the bottom with moraine material, resulting from one of the local glaciers, 

 which were very numerous in this high region. 



At Forest City, the beds have a northeast strike, and dip 35° to the 

 southeast. Toward the summit of the ridge south of this point, the appear- 

 ance of several interstratified quartzite beds indicates the horizon of the 

 upper Wahsatch limestone, which here consist of light-gray and whitish 

 limestones, with white, pink, and yellowish siliceous shales, the latter 

 enclosing cherty seams. At their base were found 



Spirifer cameratus, 



Aviculopeden occidentalis, 



so that the palaeontological evidence confirms that of the physical character 

 as to the correspondence of these beds with those which form the summit of 

 Timpanogos Peak. These beds have a dip of 40° on the southern slopes, 

 while the ridge between this and Provo Valley is seen to be formed of the 

 Weber Quartzites, of which the croppings are distinctly visible along the 

 western slopes of the spur which runs south from just west of Medway. 

 The Wahsatch limestones of the northern slopes of the ridge rise toward 

 the north, and, at the upper bend of American Fork, 2 miles above Forest 

 City, form a wall 4,000 feet in height. Here their strike bends abruptly to 

 the northwest, with the direction of the canon. 



The face of the spurs north of the stream, at Forest City, is formed 

 of a dark, almost black, close, even-grained limestone, having in places 

 a fetid odor, which stratigraphically corresponds to the Nevada Devonian ; 

 although careful search revealed no fossils sufficiently well preserved to 

 confirm this palseontologically, the fragments of EuompTialus, Froductus, and 

 Crinoid columns obtained have a resemblance in general appearance to those 

 of other welhdetei-mined' localities, like Logan and Ogden Canons. In the 

 ravine north of Forest City, the Ogden Quartzite is exposed in section, 

 resembling the typical development at the head of Cottonwood Canon 

 in the conglomerate of large pebbles of limpid quartz, having a pinkish tinge 

 in the matrix, which occurs near the middle, and in the body of purple 

 and greenish argillaceous slates near its base. The lower rocks between 

 this and the granite body have suffered very considerable dislocation and 

 displacement, especially in the spur enclosed within the sharp bend of the 



