194 GEOLOGY OF THE HIGH PLATEAUS. 



been uninterruptedly exposed to erosion, and it is by no means surprising 

 that the average degradation should have been many hundreds or more 

 than a thousand feet There is no evidence that they are old cones piled 

 up of erujitive matter around local vents, but are unmistakably carved out 

 of a mass of interstratified lava sheets and bedded fragments, like great 

 cameos, and their altitudes notably augmented by local uplifting. 



The summit of Little Creek Peak gives a fine view of the surround- 

 ing country, though the altitude is insufficient to command the great expanse 

 of the Markagunt to the southward, which is higher than the peak itself 

 But north and east the prospect is excellent. As soon as the firs and 

 spruces are cleared the Tushar is in full view to the northward, the grand 

 pyramids of Belknap and Baldy stand out in splendid relief against the 

 horizon, and the inclined plateau, whose summit they crow«, is seen in 

 detail. It may be recalled that this plateau slopes to the west, while the 

 Markdgunt slopes to the east. The Hurricane fault bounds the western 

 front of the Markdgunt, while the Tushar has a great fault upon its east- 

 em front. The two plateaus gradually merge into each other through the 

 intervening area of Dog Valley. The shifting of the displacement from 

 the west front of the Markdgunt to the east side of the Tushar is an inter- 

 esting structural feature and worth}- of a careful study, for it is often 

 repeated in the Basin ranges, and constitutes one of the most important 

 modifications of that type of structure. We may for present purposes 

 regard the Tushar and Markagunt as a single block, of which the length is 

 nearly 80 miles and the width a little more than 20. The southern por- 

 tion is tilted eastward (Markagunt) and the northern portion is tilted 

 westward, while the intervening or middle part is warped and otherwise 

 flexed. Now if this great block were a simple warped surface, the middle 

 portion would be synclinal. In reality it is an anticlinal area. An anti- 

 clinal axis leaves the Hurricane fault at a very acute angle, and crosses the 

 block obliquely to the commencement of the Tushar fault. These structu- 

 ral features may be discerned distinctly from the summit of Little Creek 

 Peak. 



Looking westward from the same point we behold in the foreground 

 a scene eminently characteristic of the western border of the Markagunt. 



