70 Explorations and Surveys for the Pacific Railroad. 



Low mountains or hills are known to exist between the Black 

 Hills and the Wind Eiver chain, about the headwaters of the 

 Yellowstone and Missouri ; but this region is too little known 

 to be treated of with confidence, and when explored may have 

 a decided effect in modifying this classification. 



System No. 2. — If, from the Great Northern Bend of the Mis- 

 souri, we travel west for 450 miles, we come again upon what 

 are called the Eocky mountains ; and still further west lies the 

 Coeur d'Alene, or Bitter Eoot range, the two enclosing the Bitter 

 Eoot or St. Mary's valley ; and both are considered as forming 

 a part of this system. Following it to the south, it includes the 

 Wind Eiver chain, the Bear mountains, the Uinta mountains, 

 and the Wahsatch, which last continue as far south as it has 

 been explored, probably forming the divide between the Great 

 Basin and the Colorado, till the junction of the latter with the 

 Gila. 



System No. 3. — From the junction of the Gila and the Colo- 

 rado, we find continuous mountains running to the northwest, 

 and terminating at Point Conception, on the Pacific. On the 

 south they are joined by the mountains forming the Peninsula 

 of California, the junction being at the San Gorgonio Pass, in 

 latitude 33° 45'. 



On the north, two chains leave this range in latitude 35°. 

 One, called the Coast range and Coast mountains, lies to the 

 west of the San Joaquin and Sacramento valleys, the waters of 

 which break through them at the Bay of San Francisco. The 

 other, called the Sierra Nevada, lies to the east of these valleys. 

 A great depression, forming a plateau, is known to exist in the 

 Sierra Nevada in latitude 40° 30', and another in latitude 42° 

 45', near Lake Abert. This chain may, perhaps, be considered 

 as terminating at or in these plateaus, or to find its continuation 

 in the Cascade or Coast range, which extend into the British 

 possessions, being broken through by the Columbia and partly 

 by the Klamath rivers. 



The Blue mountains, to the south of the Columbia, represented 

 as having a general northeast direction, may be considered, along 

 with the mountains mentioned since leaving the Colorado, as 

 forming system No. 3. 



The Humboldt Eiver chain, running north and south, (where 

 crossed,) and separating the waters of the Humboldt or Mary's 

 river from those of the Great Salt Lake Basin, is a marked fea- 

 ture ; but as to its connexion, north or south, with other ranges, 

 nothing is certain. 



There seem good reasons for believing that the east and west 

 ranges, represented as separating the Columbia Eiver basin from 

 the Great Basin, as well as the range represented as extending 

 west from the Vegas of Santa Clara, are only apparently such, 



