SANDSTONE DIKES OF UTE PASS. 131 



the opposite (east) side the Red Beds (Triassic) dip 

 in the same direction 40° to 60°, the dip increasing rapidly 

 eastward. 



On the next main spur east of the tunnel the southern 

 boundary of the dike sandstone is found in the same direct 

 line and evidently hades southwest. Northward from this 

 contact the sandstone is exposed continuously for a breadth 

 of nearly if not quite five hundred feet, or to the extreme 

 end of the spur, with no distinct appearance of bedding. 

 The Ute fault clearly forms the northern boundary of this 

 great dike, every exposure on this line showing the dike 

 sandstone in contact with either the Fountain series or the 

 Red Beds. In following this boundary eastward it is found, 

 on the west side of the last spur referred to, to be shifted 

 to the northward about three hundred feet by an obliquely 

 transverse fault, the course of which is readily traced by 

 a superb zone of crush breccia. This zone, fifteen to twenty 

 feet wide and vertical, is a complete breccia of the dike 

 sandstone in angular fragments of all sizes, mingled with 

 the quartz pebbles and cobbles of the Fountain conglom- 

 erate, and with the finer part of the Fountain series as 

 a paste. Near the re-entrant angle where the fault should 

 enter the dike, the crush breccia terminates abruptly 

 against a transverse fissure hading S. E. about 20° and 

 containing a thin seam of reddish brown clay and sand- 

 stone. It is probable, however, that the fault continues 

 obliquely across the spur along some offset parallel line 

 not now clearly exposed. 



On the next spur to the eastward the dike sandstone 

 seems to form a comparatively narrow bund, possibly one 

 hundred feet wide, across its steep north end. North 

 of it are the Red Beds, and south of it all is granite. 

 Beyond this spur is the main west branch of Red Rock 

 Caiion. Along the west side of this gulch is another very 



