ANNOTATIONS AND ADDITIONS. 47 



direction of the great chain of the Aldan mountains in the 

 east of Asia, which divides the streams flowing into the 

 Lena from those which flow towards the Pacific, if prolonged 

 on the surface of the globe in the direction of a great 

 circle, passes through several summits of the Eocky Moun- 

 tains, between the parallels of 40 and 55 "Thus an 

 American and an Asiatic chain of mountains appear to 

 belong to one great fissure, following the direction of a 

 great circle, or the shortest course from point to point." 

 (Compare Erman's Eeise um die Erde, Abth. I. Bd. iii. S. 

 8, Abth. II. Bd. i. S. 386, with his Archiv fur wissen- 

 schaftliche Kunde von Eussland, Bd. vi. S. 671). 



The Eocky Mountains which sink down towards the 

 Mackenzie Eiver which is covered a large portion of the year 

 with ice, and the highlands from which single snow-clad 

 summits rise, are altogether distinct from the more westerly 

 and higher mountains of the coast, or the chain of the 

 Californian Maritime Alps, the Sierra Nevada de California. 

 However ill selected the now generally used name of the 

 Eocky Mountains, to designate the most northerly continu- 

 ation of the Mexican Central Chain, it does not appear to 

 me desirable to change it, as has been often proposed, for 

 that of the Oregon Chain. Although these mountains do 

 indeed contain the sources of Lewis's, Clark's, and North 

 Eork, the three chief branches which form the mighty 

 Oregon, or Columbia Eiver, yet this river also breaks 

 through the Californian chain of snow-clad Maritime 

 Alps. The name of Oregon District is also employed 

 politically and officially for the smaller territory west of the 



