192 J. D. Dana — Rocky Mountain Protaxis and the 



has the great height of 12,892 feet.* The Wasatch range is 

 lower than the Uinta, but also steeper and narrower, and in 

 the making it was far more roughly wrenched and broken, and 

 hence must have lost much more by erosion. 



The great area of trachyte (35x9 miles) over the interval 

 between the Uinta and Wasatch Mountains and the two small 

 areas on the same northwest line in the low Eocene area, the 

 last just south of Weber, indicate that " the entire length of 

 this trachytic vent was about fifty miles." This outflow is 

 described as an effect of the mountain-making movements — a 

 faulting according to King. 



One of the great results of the 40th Parallel Survey brought 

 out by Mr. King is the establishing of the fact that the Great 

 Basin, between a line near the Great Salt Lake and the merid- 

 ian of HTijr , was raised above the sea-level at the close of the 

 Carboniferous, or simultaneously with the making of the 

 Appalachian Mts., it being proved that the Carboniferous 

 rocks were the latest marine formation. The Oquirrh Moun- 

 tains were part of the eastern margin of this Mesozoic dry 

 land. No Triassic, Jurassic, or Cretaceous beds are reported 

 from the eastern base of the Oquirrh or the western of the 

 Wasatch in any part of the Salt Lake region, or over the 

 region west until the meridian of 117^-° W. is passed. 



In discussing the origin of the Wasatch, Mr. King states the 

 principle, gathered from his observations, that in case of each 

 great mountain-making flexure, wherever an Archaean moun- 

 tain range existed beneath accumulated sediments, there a fold 

 had taken place. He observes that "in the case of the 

 Wasatch, it is seen from the relations of the old Archaean 

 underlying range, that this enormous mountain body deter- 

 mined the existence and character of the post-Cretaceous fold." 

 He immediately adds : " In the case of the Uinta, it is impos- 

 sible to say how far underlying Archaean rocks played a part. 

 The single limited outcrop of pre- Cambrian rocks at Red 

 Creek (in its northeastern side) is certainly at the most rup- 

 tured and actively dislocated point of the whole Uinta Range." 

 Mr. King, although not adopting the contraction theory of 

 mountain-making to its full extent, still gives to tangential 

 compression a prominent place in the process. He observes 

 (on page 752) that when a tilting of strata against an Archaean 

 ridge has taken place " it is evident that the interval of 

 Archaean rock must have been compressed, and in yielding to 

 this force the Archaean bodies have developed an amount of 

 plasticity which, in view of their crystalline nature, is very 

 surprising." 



* This high region is continued eastward, and in the next quarter of the range 

 there are, among the heights, Gilbert Peak, 13,687 feet, and Emmons Peak, 

 13,694 feet, each near the meridian of 110° 20' W. 



