144 GUIDEBOOK OF THE WESTERiN" UNITED STATES. 



Ogdcn to Yellowstone. The first bridge above the station crosses 

 Robinson Creek.^ 



Just beyond tliis bridge the train crosses Warm River and begins 

 to ascend along its west bank. The grade of the track is greater than 

 that of the stream, so the train is soon well above the dashing, tum- 

 bhng, noisy brook. From this place to Mesa the angler will mentally 

 choose his flies and long for a chance at the trout that must be hidden 

 in those pools and rapids. Little will he care that the roadbed is a 

 niche cut in rhj'ohtc and that there is a small fault marked by little 

 springs in opalescent-colored lava just below milepost 62. Immedi- 

 ately at the milepost the rhyolite is turned on edge, crushed, and clay 

 streaked, but the beds at the top of the cut are horizontal, showing 

 that there was considerable disturbance and faulting before the later 

 lava flow. The dashing mountain stream, tumbhng and jumping 

 over bowlders, makes a more vivid appeal to the traveler than the 

 evidences of that stream's ancient history, wliich is recorded in the 

 thick beds of finely sorted sand and the thin beds of gravel exposed 

 above and below the tracks at milepost 63. This material was depos- 

 ited in ponded water after the river had cut its channel nearly to 

 the present depth. To the question, What and where was the dam 

 that made a pond 100 feet deep in this canyon ? the geologist has not 

 yet found an answer. 



Near milepost 63 a 561 -foot tunnel is to be driven to avoid the 

 danger from the scaling off of rocks in the points around which the 

 track now winds, A short distance beyond the trestle, at milepost 

 66, the train leaves the canyon and comes out on a flat surface under- 

 lain by basalt. 



Mesa is a siding and Y in a natural park in the forest. The prin- 

 cipal thuber seen here is Douglas fir. From Mesa the serrate crest of 



the Teton Range is again in view, and a mile or two 



away on the right is the front of a great sheet of lava, 



oSSSI"^^' now covered with grass and trees, rising 500 feet above 



the flat. 



About 4 miles southwest of Mesa Henrys Fork plunges over a 

 precipice 96 feet high with a sheer drop, and a mile below there is 



1 The discharge of all three streams has heeu gaged near this station with the fol- 

 lowing results, expressed in second -feet (cubic feet a second): 



Henrys Fork, 1910-1913. 

 Warm River, 1912-13. . . 

 Tlobinson Creek, 1912-13 



Maximum. 



Minimum. 



3,300 



900 



1,140 



705 

 192 



53 



Mean. 



1,260 



295 

 ISO 



There 



irr 



