SANDSTONE DIKES OF UTE PASS. 121 



in consequence of its proximity to the faults. Above the 

 tunnel is a craggy and highly brecciated mass of quartz- 

 ite, which extends down through the tunnel. On either 

 side of this, and extending twenty to fifty feet beyond 

 the ends of the tunnel are soft, decomposed, ochrey 

 rocks, apparently ferruginous and manganiferous clays 

 occurring as residuary impurities of a crushed limestone 

 (base of the Manitou limestone). East of the tunnel, 

 sandstone like that of the west end of the section dips 

 northeast 60° at first and then changes abruptly to dips, 

 away from the railroad on either side, of 10° to 30°. 

 East of this tunnel (Fig. 1) is another about two hundred 

 feet long with open cuts giving again a continuous section 

 of about four hundred feet, the distance between the two 

 sections being about four hundred and fifty feet, following 

 the railroad. The second section shows in the cut west 

 of the tunnel, or for about one hundred feet, the varie- 

 gated and structureless dike sandstone. The tunnel and 

 first fifty feet of the eastern cut are in coarse granite 

 with numerous small (one to four feet) dikes of sand- 

 stone. A very regular dike cuts the tunnel at the east 

 portal, widening downward from one to three feet, with 

 a westerly hade of 10° to 20°. Most of the dikes are 

 transverse to the tunnel, but they run in all directions 

 and are extremely irregular. Midway of the eastern cut 

 the granite overlies the soft, red and white sandstones 

 of the Fountain series, the contact hading southwest about 

 45°, while the sandstone dips northeast 70°, approx- 

 imately (Fig. 2). Both rocks, and especially the granite, 

 show much crushing near the contact. This is very 

 obviously the continuation of the Ute fault, crossing the 

 railroad obliquely and trending in a southeasterly direc- 

 tion, with the Fountain series on one side and the coarse 

 granite with sandstone dikes on the other. 



