612 OREGON. 
reaching Fort Vancouver, less than a hundred miles from the coast. 
This great mountain, the backbone of Western America, is, therefore, 
no narrow line of summits, but spreads out over a base of more than 
fourteen hundred miles, one foot literally bathed by the waters of the 
Mississippi, and the other dipping beneath the Pacific. This fact is 
well shown in a sectional view by Fremont,* one of the interesting 
results of his valuable explorations. ‘Two hundred and fifty miles 
from the Mississippi, at the mouth of the Kansas, the height above 
the sea was found to be nine hundred feet. For one hundred and 
twenty-five miles beyond, the whole ascent was but one hundred 
feet; in the next one hundred and thirty-five miles, there was a rise 
of one thousand feet, making two thousand feet above the sea; the 
next one hundred and thirty-five miles, another one thousand feet, 
making three thousand feet; the next two hundred and fifty miles, a 
rise of two thousand feet ; making, in all, five thousand feet in a dis- 
tance of six hundred and thirty miles, or very nearly eight feet to the 
mile. Over the next four hundred miles, the route travelled ranged 
between five thousand and eight thousand feet ;} this was the summit 
region of the Rocky Mountains, upon which the Wind River Moun- 
tains stand, with their summits about six thousand feet above the 
country around them, or thirteen thousand five hundred and seventy 
feet above the sea. Beyond, to the westward, the section shows very 
remarkably that the descent was gradual like the ascent, excepting 
irregularities arising from some high ridges. 
The Rocky Mountains are properly, therefore, a gentle swelling 
of the surface, whose average inclination is between seven and eight 
feet to the mile. Over the surface, on the declivities as well as at top, 
are lofty ridges or mountains, and of these the Wind River chain is 
one of the most prominent. In many parts at top there are exten- 
sive plains; and Humboldt long ago informed us that in the Mexi- 
can portion, wheeled vehicles may travel along the range for two 
* Report of the Exploring Expeditions to the Rocky Mountains in the year 1842, and 
to Oregon and North California in the years 1843 and 1844, by Brevet Captain J. C. 
Frémont, of the Topographical Engineers, under the orders of Col. J. J. Abert, Chief of 
the Topographical Bureau. Printed by Order of the Senate of the United States. Wash- 
ington, 1845. 
The same extremely gradual slope characterizes the Andes of South America, as is 
well shown in a sectional view of the Bolivian chain, by M. Alcide D’Orbigny, in his 
Voyage dans l’Amerique Meridionale, Geologie, Plate 8, fig. 1, bis. 
t The pass was found to have a height of seven thousand four hundred and ninety feet. 
