236 Tertiary. 



Witches' Rock, Eagle Rock, Hanging Rock, Conglomerate Peak, Sen- 

 tinel Rock, Monument Rock, etc. Monument Rock is a regular 

 obelisk of conglomerate, standing at the junction of the Echo with the 

 "Weber valley, and being about 250 feet high. Descending the Echo 

 canon, the more rugged picturesque scenery is exhibited on the right 

 hand, and descending the Weber the same lofty perpendicular wallsi 

 weathered here and there into all sorts of fantastic forms, continue to 

 the Narrows, where the Weber river makes a bend to the left, and the 

 conglomerates disappear. The whole series of these beds is referred to 

 the Wasatch Group, and the thickness estimated at from 3,000 to 5,000 

 feet, the conglomerate portion being from 1,500 to 2,000 feet. 



He proposed the name of the " Sweetwater Group," for a lake deposit 

 found in the Sweetwater valley. There is a high ridge or divide, 

 between the drainage of Wind river. North Platte, and Sweetwater, 

 300 to 400 feet above the channels of these streams, which is com- 

 posed of the Tertiary beds. The Sweetwater forms a distinct concavity, 

 with this high divide on the north and east, and the valley has been 

 scooped out so that until we reach the Sweetwater Canon, near the 

 South Pass, only the massive granite ridges rise up among the modern 

 Tertiary beds, which jut close up against their base. This is a vallc}^ of 

 denudation, over a space of at least 30 to 50 miles in width. All the 

 unchanged formations, from the lignite Tertiary down to the massive 

 feldspathic granites, have been worn away, leaving the granites scat- 

 tered over the valley in the isolated ridges. At that time there ?vas a 

 fresh-water lake which occupied the entire valle}', much as Salt 

 Lake once occupied the great basin, concealing most of the granite 

 ridges, while others rose above the waters like islands. Then was de- 

 posited what he called the Sweetwater Group, or perhaps a series of 

 beds identical with the upper portion of the Wind river deposits. 

 These were scooped out again in time, and the Pliocene marls and 

 sands were deposited; and then again there M^as another scooping out 

 of the valley, and finally a covering of the hills with drift. 



The mountainous portions of Northern Utah* are full of beautiful 

 park-like areas, which contain the -evidences oi an ancient lake. At 

 Copenhagen there is a considerable drift or bowlder deposit with fine 

 white or yellow marly sands and clays, in regular layers, showing the 

 deposit to be Post-pliocene, and that the waters of the lake were com- 

 paratively^ quiet. Near Box Elder Canon are two kinds of terraces, 



* U. S. Geo. Sur. of Montana, etc 



