408 DESCRIPTIVE GEOLOGY. 



The canon of Blacksmith's Fork breaks through the range some seven 

 or eight miles south of Logan Canon. From where the stream leaves the 

 mountains to the Bear Lake road, on the Cambrian Plateau, the canon 

 measures about twelve miles in length. It affords some of the most beau- 

 tiful canon scenery to be found within the limits of this survey. Other 

 gorges and passes possess doubtless more grandeur, and are built up of 

 larger proportions, but few combine grandeur, picturesqueness, and variety 

 of .outline to the same extent as Blacksmith's Fork. In width, the canon 

 is exceedingly narrow, with abrupt, precipitous walls rising from 2,000 to 

 3,000 feet in heavy masses above the stream-bed. At its entrance, the beds 

 of Wahsatch limestone are found dipping to the eastward. They gradually 

 become horizontal, and then assume a westerly dip, forming a continuation 

 of the synclinal fold seen to the north. The westerly-dipping beds seldom 

 reach a high angle, inclining rarely more than 12° to 14°. The limestone 

 is a dark bluish-gray rock, compact in texture, with occasional beds more 

 granular and of lighter color. The bedding-planes are distinctly marked, 

 and the thickness of single beds sometimes reaches 20 or 30 feet. As the 

 upper beds are never seen, it is impossible to estimate the entire thickness 

 of limestone at this point : probably not less than 5,000 feet are exposed. 

 The only fossils observed were a few indistinct impressions of coralline 

 stems protruding from the surface on the walls of weathered limestone. 

 Beyond the Wahsatch limestone occur the beds referred to the Ogden 

 Quartzite and the cherty, siliceous strata of the Silurian or Ute lime- 

 stone. Some eight miles above the entrance of the caiion, the Cambrian 

 quartzites come in with a gentle dip to the westward, gradually flattening 

 out to a horizontal position. Between Blacksmith's Fork and the canon of 

 the Muddy, a distance of six to eight miles, the limestones lie nearly hori- 

 zontally, the easterly- dipping beds occupying less and less area, and the 

 little synclinal roll gradually dying out under the valley. 



Muddy Canon. — In its general features, the Muddy Canon presents 

 much the same character as Blacksmith's Fork, the dark heavy beds of 

 bluish-gray limestone of the Wahsatch group forming the abrupt canon- 

 walls at its entrance. Here the beds are inclined at a low angle to 



