416 DESCRIPTIVE GEOLOGY. 



The tufa is a compact, cream-colored rock, inclosing some minute shells and 

 incrustations of stems and twigs. 



On the south fork of Ogden River, just above the junction of Beaver 

 Creek, heavy beds of nearly horizontal dark limestones occur, which there 

 form the abrupt canon-walls, until concealed beneath the Vermillion Creek 

 beds. No fossils were found in the limestones, but, from their. relative posi- 

 tion, they have been referred, on stratigraphical grounds, with but little hesi- 

 tation, to the Ute limestone. From the junction of Beaver Creek with Ogden 

 River to the mouth of the upper canon in Ogden Valley, the exposures are 

 mostly in white or reddish-brown quartzites, whose walls rise between 1,000 

 and 1,500 feet above the stream-bed. The same purplish-gray beds which 

 form so prominent a feature in Beaver Canon occur here also, striking diago- 

 nally across the canon. 



The foot-hills along the east side of Ogden Valley, between the Upper 

 Ogden Canon and the base of Eyrie Peak, were not visited, but they pre- 

 sent, from the valley, long, steep ridges, frequently broken by deep, narrow 

 canons, extending far back into the interior of the range. In crossing 

 the divide, between Ogden and Cache Valleys, quartzite beds are passed 

 over for the greater part of the distance, which, on the summit of the 

 pass, attain an altitude of about 1,000 feet above the Tertiaries of Ogden 

 Valley. Eyrie Peak, which lies to the eastward of the pass, rises still 

 higher, nearly 3,500 feet, commanding a broad view in all directions. It is 

 composed entirely of quartzite from base to summit, whose beds dip appar- 

 ently to the northeast at an angle of 18° to 25°, with a strike of north 30° 

 west. The top of the peak is composed of dark brownish-white beds, car- 

 rying considerable iron disseminated through them, and concentrated into 

 thin seams or layers. Near the bottom of the series, the beds possess a 

 decidedly bluish tinge, showing a marked resemblance to the purple beds 

 of Beaver Canon, with occasional layers of conglomerate made up of coarse 

 sand, carrying smooth, round pebbles. Throughout the series are frequently 

 found intercalated seams of dark shales and fine sand beds. This entire 

 series of beds has been referred provisionally to the Cambrian quartzites- 

 partly on structural grounds, and in part from strong, well-marked petro, 



