GEOGRAPHY OF NORTH AMERICA. 209 



ing mountainous, and therefore more or less timbered, and 

 one eighth valuable land. At one point beds of coal of 

 great extent were found. The limitless expanse of bunch- 

 grass land affords, in some otherwise desert country, grazing 

 to enormous herds of cattle. Some parts of the country are 

 not so desolate. In the western portion of the Green River 

 district, the valley of the Bear River, which doubles so curi- 

 ously upon itself near the famous soda-springs of Idaho, al- 

 ready supports a thriving population. Along its banks and 

 in the neighboring region are fine acres of farming land, 

 grass-covered hills, broad and fertile valleys. Throughout 

 the region, the party noticed that the season was much colder 

 than that experienced at the same altitudes in Colorado. In 

 the mountainous regions to the north, especially along the 

 western flanks of the Wind River range, remains were no- 

 ticed of huge ancient glaciers ; and, considering the enor- 

 mous amount of snow and ice that was observed at the begin- 

 ning of August, the geologists deemed that the discovery of 

 still existing glaciers in that range would not be surprising. 

 Moraines covering many square miles, often a thousand feet 

 in thickness, extend downward through narrow valleys, now 

 containing rushing streams ; and, from all appearances, cessa- 

 tion of glacial activity must have occurred within a compar- 

 atively recent time, for scarcely any vegetation has sprung 

 up on the light glacial soil, and the morainal deposits them- 

 selves bear every mark of freshness. 



In the comparatively level country lying wholly within 

 the Territory of Wyoming, stretching from the Wind River 

 and Sweetwater Mountains to the Uintas, and throusrh the 

 middle of which the Pacific Railroad winds its way, the ge- 

 ologists found little besides nearly horizontal Tertiary strata, 

 such as occur along the line of the railway. The mountains 

 west of Green River are composed mainly of Carboniferous 

 limestones, but are flanked on either side by hills of Jurassic 

 and Cretaceous age, with Tertiary beds resting on the tilted 

 edges of the older rocks. Still farther west, the Bear River 

 Mountains in Utah are composed of Silurian and Carbonifer- 

 ous rocks limestones and quartzites. To the north of the 

 abrupt bend in Bear River the lower grounds are covered 

 with basalt flows, evidently originating from numerous cra- 

 ters still remaining in the vicinity. This outflow accounts 



