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GUIDEBOOK OF THE WESTERN UNITED STATES. 



the place where it is upturned and cut by the river between the rail- 

 road and the mountain. As seen from the train the country to the 

 right of the La Sal Mountains is exceedingly rough and rugged, 

 being cut into great canyons with vertical sides or left in giant blocks, 

 also with vertical sides. In fact, the traveler is now approaching 

 a region in which the expression of the topography is different from 

 anything that he has yet seen, unless he is already acquainted with 

 the counti-y that was called by Powell the "Canyon lands." In 

 this region Hogarth's " line of beauty " is unknown. The slopes of 

 the hills and mountains do not show gracefully curved lines from 

 summits to bases, but each slope forms a straight line and unites 

 with its neighbor in an angle and not a curve. The valleys are all 

 canyons, which either have vertical sides or sides composed of 

 straight lines, and the intervening spurs are mesas with flat tops as 



Figure 52. — An^lar profiles of the Plateau province. 



shown in figure 52. A glance at the country on the right of the La 

 Sal Mountains will show some of the angularity mentioned. This 

 characteristic feature of the land forms is illustrated in Plate 

 LXXXII, A, which is a view taken near Moab. It also shows some 

 of the slender towers of rock which the traveler may see from the 

 train. 



Although the La Sal Mountains have attracted much attention, 

 another group of mountains, which are even more interesting, are 

 slowly appearing above the horizon, far to the southwest. Where 

 first seen, in the vicinity of Cisco, these mountains, named the Henry 

 Mountains for Joseph Henry, the first Secretai-y of the Smithsonian 

 Institution at Washington, are fully 100 miles distant. They are 

 divided into three groups — ^the larger group at the north and two 

 isolated peaks farther south.^^ These mountains lie on the west side 

 of Colorado River, which in this region flows in a canyon 1,000 

 feet deep. 



•* The study of the Henry Mountains 

 ill 1876 by G. K. Gilbert led to the dis- 

 covery of a new type of mountain, 

 which is indirectly of volcanic origin 

 but is not a volcano. It is now known 

 that the La Sal Mountains and many 

 other similar groups in the Plateau 

 province belong to the same class. 

 Gilbert found that the peaks of the 



Henry Mountains are composed largely 

 of hardened lava, which, when it was 

 in a molten state, instead of ascending 

 to the surface through some fissure 

 in the rocks and then pouring out over 

 the surrounding country as a lava 

 flow, welled up in the earth's crust 

 untU it lifted the covering rocks and 

 forced them up in a great dome. As 



