HAGOT.1 YELLOWSTONE FALLS TO MAMMOTH HOT SPRINGS. 359 



means displayed on so grand a scale. The summit here has an eleva- 

 tion of S,100 feet, and is for the most part formed of various modifica- 

 tions of glassy rhyolite. The road with a gradual descent follows 

 down the (ribbon River valley through a pine forest characteristic of 

 the Park. At the picturesque Virginia cascade, on the (ribbon, the 

 rock exhibits most interesting forms of erosion in the easily crumbling 

 rhyolite. Three miles beyond the Virginia cascade, Norris basin is 

 reached, andJfrom here to Mammoth Hot springs the route follows the 

 same road traversed upon entering the Park. 



Plates III and IV are from sketches made during the excursion by 

 MM. Eysseric and Golliez of the visiting geologists. 



