444 G. F. LOUGHLIN 
The Mississippian limestone is followed upward by a consider- 
able thickness of limestone, shale, and sandstone, which is succeeded 
by the Weber (Pennsylvanian) quartzite, and the Weber in turn is 
overlain by the Park City (Permian?) and Mesozoic formations. 
No measurements of the thickness of any of these formations 
were made. 
THE AMERICAN FORK-ALPINE DISTRICT 
The strata along upper American Fork Canyon south of Mary 
Ellen Gulch are almost entirely of the great limestone belt, strik- 
ing about parallel to the neighboring granite contact and dipping 
away from it (see Fig. 2). The dip undulates gently, and at one 
place erosion has evidently exposed the top of the quartzite, pre- 
sumably along a low anticlinal flexure; but the one quartzite out- 
crop found is completely isolated in an area of glacial drift, and its 
structural relations can only be inferred. Near the great bend in 
American Fork Canyon the uniformity of strike and dip is inter- 
rupted by an anticlinal or domal structure in which the Cambrian 
quartzite is exposed along the lower canyon walls. The southern 
part of the dome is cut off by an E.-W. fault, with relative upward 
movement on the north side. —Two miles below the bend, the quartz- 
ite is again exposed along the lower canyon walls in a second domal 
uplift. About midway between this second dome and the town of 
Alpine to the northwest, the quartzite is again exposed in a third 
domal uplift, which like the first is broken by a fault. The fault 
is exposed along the range front and is clearly of the reversed type, 
with steep northward dip (toward the granite). As these faulted 
dome structures are essentially small duplicates of the great faulted 
dome around the intrusive granite, they may indicate the presence 
of unexposed intrusive granite bosses south of the exposed granite 
area. This suggestion is strengthened by the fact that the southern 
granite contact pitches southward beneath the contact-metamor- 
phosed limestones. The southerly pitch is well shown at the Silver 
Lake cirque about 4 miles east of Lone Peak, where limestone forms 
the west wall, and quartzite and limestone the east wall, but where 
granite forms the north wall and the floor. 
The quartzite exposures in American Fork Canyon were 
regarded as Devonian by the Fortieth Parallel Survey, as their 
