408 GEOLOGICAL EXCURSION TO THE ROCKY MOUNTAINS. 



Of the streams entering the Grand river from the north, Roan and 

 Parachute creeks drain the interior of the Book plateau, bul Rifle creek 

 drains the monoclinal valley within the Hogback ridge of Laramie Band- 

 stones which forms a semicircle around the west Hanks of the greal 

 White River plateau, breaking through this ridge in a narrow gorge six 



White Rev. 

 Plateau. 



Tertiary 



Cretaceous. Jura-Trias, Carbon- <kln. Granite. 



i/hrous. 



FIG. 22.— Section fron Book dill's to White River plateau. M 



miles (10 km.) due north of Rifle station. This great Hogback ridge, 

 which here rises 2,000 feet (610 m.) above the valley level, can be traced, 

 almost continuously, northward along- the west flanks of the Elk moun- 

 tains, then bending in ;1 curve around the White River plateau to 

 White river, and then westward along the southern Hanks of the 

 Uinta mountain uplift to the Wasatch, a distance of about 250 miles 

 (402 km.). According to Mr. \\. O. Hills, who has made a special study 

 of the coal-bearing beds, the Wasatch Eocene is also upturned on the 

 thinks of this ridge, whence he reasons that the Eocene movement (post- 

 Bridger) played an important part in the Rocky mountain uplift.' 



GO 



FIG. 28. — Section of coal scams at Newcastle. Colo. 



At Newcastle* 11 the Hogback ridge is seen in section to the west of 

 the town, where coal mines are opened on some of the numerous coal 

 veins, which contain an aggregate thickness of over 125 feet of coal. 

 These are shown in the cross section (Fig.2:>), furnished by the manager 

 of the mines, Mr. W. B. Devereux. 



About 2 miles (.3 km.) south of the town, the great 45-foot vein has 

 been burning for ages deep down beneath the surface. At many other 



