378 COSMOS. 



or less active volcanoes has become known to mariners within 

 the last seventy or eighty years, but this grouf) lay hitherto, 

 as it were, isolated, and unconnected with the volcanic range 

 of the Mexican tropical region, or with the volcanoes which 

 were believed to exist on the peninsula of California. If we 

 include the range of extinct trachytic cones as intermediate 

 links, we may be said to have obtained insight into their im- 

 portant geological connection over a gap of more than 28 

 of latitude, between Durango and the new Washington terri- 

 tory, northward of West Oregon. The study of the physical 

 condition of the earth owes this important step in advance to 

 the scientifically well-prepared expeditions which the govern- 

 ment of the United States has fitted out for the discovery of 

 the best road from the plains of the Mississippi to the shores 

 of the South Sea. All the departments of natural history 

 have derived advantage from those undertakings. Great 

 tracts of country have been found, in the now explored terra 

 incognita of this intermediate space, from very near the Rocky 

 Mountains on their eastern slope, to a great distance beyond 

 their western descent, covered with evidences of extinct or 

 still active volcanoes- (as, for instance, in the Cascade Mount- 

 ains). Thus, setting out from New Zealand, and ascending 

 first a long way to the northwest through New' Guinea, the 

 Sunda Islands, the Philippines, and Eastern Asia, to the 

 Aleutians; and then descending toward the south through 

 the northwestern, the Mexican, the Central American, and 

 South American territories to the terminating point of Chili, 

 we find the entire circuit of the basin of the Pacific Ocean, 

 throughout an extent of 26,400 geographical miles, sur- 

 rounded by a range of recognizable memorials of volcanic 

 action. Without entering into the details of exact geograph- 

 ical bearings and of the perfected nomenclature, a cosmical 

 view such as this could never have been obtained. 



Of the circuit of the great oceanic* basin here indicated 

 (or, as there is but one united mass of water over the whole 

 earth, we ought rather to say the circumference of the larg- 

 est of those portions of it which penetrate between conti- 

 nents) it remains for us now to describe the tract of countiy 

 which extends from Rio Gila to Norton's and Kotzebue's 



* The term "Grand Ocean," used to designate the basin of the 

 South Sea by that learned geographer, my friend Contre-amiral de 

 Fleurieu, the editor of the Introduction Historique au Voyage de Mar- 

 chand, confounds the whole with a part, and consequently leads to 

 misapprehension. 



