342 DESCKIPTIVE GEOLOGY. 



There are indications that at the close of the Jurassic period commenced 

 a general uplift and folding of these beds, while at the close of the Cre- 

 taceous period, after the deposition of an additional thickness of over 10,000 

 feet of stjata in the seas which washed its eastern flanks, occun*ed a more 

 general movement of upheaval, which produced the main elevation of this 

 range. While the movements of these two periods are those of which the 

 most evident traces are left, it is probable that there was a continental 

 elevation at the close of the Carboniferous period, which cut off the Triassic 

 and Jurassic seas from the region to the west of the Wahsatch, without pro- 

 ducing any appreciable non-conformity in their deposits, and that less im- 

 portant movements have occurred in the range after the Cretaceous upheaval, 

 even into late Tertiary times. An additional feature is presented by the 

 occurrence of eruptive rocks of later date than the granites, which, in Meso- 

 zoic limes, consisted of granite-porphyries and diorites, traversing the Palae- 

 ozoic rocks in narrow dikes, and in Tertiary times of trachyte outflows, 

 which covered considerable areas. 



Before proceeding with a local geological description of the range in 

 detail, it may be well to give a concise enumeration of the local groupings 

 adopted for those formations, which are differently developed from corre- 

 sponding horizons already described in the eastern region. 



In the following table, the third column gives the names adopted in the 

 Wahsatch region for the local divisions, made according to the predomi- 

 nating lithological characteristics of the beds. In the second column are 

 given the corresponding letters used on the map to designate the several 

 color-divisions, which indicate respectively the following geological horizons: 

 P.iziPermo-Carboniferous limestones. 

 Crr Upper Coal-Measure limestones. 

 U. C.rr Middle Coal-Measure quartzites. 

 L. C. = Lower Coal-Measure limestones. 

 S. C.zzSub- (or Lower) Carboniferous limestones 



D.::^ Devonian limestones. 

 0. D.^ Devonian quartzites. 

 S.rr Silurian limestones. 

 Ca.:= Primordial quartzites and slates. 



