ANTICLINAL STRUCTURE. H9 



connection with the Eureka Mountains by a complicated system of ridges 

 which closely unites them with both Prospect Ridge and the Mahogany 

 Hills. Although their northern limit is very ill denned, they stretch in a 

 north and south direction for 10 or 12 miles and measure about 5 miles in 

 width, with an elevation above the surrounding valleys of over 2,000 feet. 

 Bellevue and White Cloud Peaks are the two most prominent points in the 

 mountains, the former with an altitude of 8,883 feet, the latter of 8,850 feet 

 above sea level, while between them is a still higher table-topped summit, 

 having an elevation of 8,951 feet above the sea. 



In structure the main body of Fish Creek Mountains consists of an 

 anticlinal fold, whose axis lies along the eastern edge of the broad, slightly 

 inclined table which forms the top of the range. A north and south line 

 of faulting coincides with this axial plane and is accompanied by an escarp- 

 ment, nearly 600 feet in height, showing a downthrow at least equal to 

 that amount. The displacement may be traced readily for a considerable 

 distance along the mountain. The fault is not laid down on the map, but 

 the escarpment itself is indicated by the contour lines being thrown close 

 together. At the base of this cliff" the rocks are much broken up, as there 

 appears to be a series of small faults rather than one sharp displacement. 

 The anticline is nevertheless sharply brought out by the limestone dipping 

 in opposite directions with a marked difference in the angle of inclination. 

 The beds of the cliff incline at low angles into the mountains, whereas the 

 slopes upon the east side, with an average dip of 15, fall away abruptly 

 for about 1,500 feet or until buried beneath the Quaternary deposits of Fish 

 Creek Valley. On the west side of the main axis the limestones assume a 

 gentle synclinal roll, followed by a low, broad anticline, the westerly dip- 

 ping beds of which extend for nearly two miles, with a monotonous uni- 

 form dip, rarely exceeding 5 or 6, till lost beneath the detrital accumula- 

 tions of Antelope Valley. The geological structure is that of a faulted 

 anticline, gentle on one side and relatively steep on the other, a 

 structure typical of many ranges in the Great Basin. Besides the north 

 and south anticlinal fold there is a gentle quaquaversal dip from the central 

 mass about Bellevue Peak, the beds to the northward, however, dipping 

 away steeper than in the other directions. 



