406 APPENDIX E. — GEOLOGY. 



the carboniferous limestone. Judging from the relative position 

 of the limestone, and the metamorphic rocks of Antelope and Fre- 

 mont's Islands, the former occupies the position of low, synclinal 

 basins, the valleys between being produced to a large extent, pro- 

 bably by erosion along the anticlinal axes, produced by the eleva- 

 tion of the metamorphic beds. We may expect, also, that the 

 same limestone will be found on the elevated plateaus and moun- 

 tains on the east side of the lake. 



It will be seen from these facts that we have very satisfactory 

 information that this limestone of the carboniferous period is widely 

 distributed in the region around the Great Salt Lake. Its position 

 relative to the coal-bed on the North Fork of Platte Eiver has not 

 been determined ; but since no beds of coal have been observed on 

 the slopes of the mountains in the region of the Salt Lake, we are 

 left to infer that the coal is to be sought (as elsewhere) above the 

 limestone. Since the existence of coal is proved in one point, 

 (admitting the evidence in favour of its age being that of the car- 

 boniferous period,) we are warranted in the conclusion that it has 

 once existed over a much wider area, and can be sought with 

 success in the proper situations. The importance of this mineral 

 in that distant region cannot be too highly estimated, and the 

 geographical position and extent of the beds should be one of the 

 first points ascertained in the location of any route of communica- 

 tion between the east and the west. 



In comparing the notes and specimens with the map of your route 

 and the large map of the Salt Lake and adjacent country, I have 

 confined myself to indicating by a colour the kind of rock occurring 

 at each point, scarcely in any case extending this colouring even 

 when the topographical features of the country would warrant the 

 conclusion that the same rock existed. Your knowledge of the 

 character of the surface and the relative elevations will enable you 

 in many instances to determine the limits of those formations 

 marked; while, for myself, not fully understanding their features, 

 I might fall into some error. 



Hoping to see the investigations you have so well begun carried 

 still further, until we can have a good geographical and geological 

 map of this region, 



I remain, 



Very truly and respectfully, 

 Your ob't. serv't. 



James Hall. 



