GEOLOGY OF NORTH AMERICA. 
59 
then the Green mountains, the White mountains, the Berkshire mountains and the Alleghanies , all 
running' from north-east to south-west with slight deviations north— south. The highest summits of 
the White mountains do not reach 7000 feet, and those of the Alleghanies in North Carolina do 
not exceed 6700 feet. 
The Ozark mountains, forming the western boundary of this first region, are still lower than the 
Alleghanies, of which they seem to be a continuation and a sort of appendix, having the same 
direction from north-east to south-west, and having been formed at the same period, the end of the 
Coal formation. Their height varies from one to two thousand feet. 
Between the Ozark, Alleghany and Lawrentine mountains, are extensive plains, furrowed by 
deep ravines, and presenting in consequence numerous undulations, whose medium height is not more 
than three hundred feet, and tlie maximum does not exceed six hundred. 
2°. The central or Rocky mountain region embraces the country lying between the western 
limit of the eastern region and the 113° longitude west, meridian of Greenwich. It is chiefly formed 
by high mountains surrounded by elevated table lands. These elevated plains rise from the extre- 
mities towards the centre of the region with so gradual an inclination that it is almost impercep- 
tible; their medium height is four thousand f^t, some attain seven thousand and then they form 
passes between two chains of the Rocky mountains. 
The Rocky mountains form a narrow line running from south to north, with a slight deviation 
of a few degrees toward the west. This line is not continuous, being several times interrupted, 
thus forming several chains parallel to each other, and imbricated exactly like tiles upon a roof. 
The eastern chains are. called Sierra de los Organos, Sierra de Guadalupe, Sierra de Manzana, 
Sierra de Sandia, Sierra de Santa Fe , Moro Peaks, Pike’s Peak, the Rocky mountains proper. 
Long’s Peak and Laramie Peak. Their elevation above the level of the sea varies from 10,000 
to 12,500 and 13,000 feet, and they are the reservoirs for nearly all the rivers flowing into the 
gulf of Me.xico. Thus the Rio Grande del Norte, the Rio Pecos, the Canadian, the Arkansas, the 
Platte and the Missouri, have their sources in these mountains. I will here remark that the Red 
riv'er of Louisiana, which geographers have so long confounded with the Canadian, takes its rise 
at the foot of the Llano Estacado , and has no communication with the Rocky mountains ; the same 
is the case with the Rio Brazos and the Rio Colorado of Texas. Farther to the west the Rocky 
mountains are formed by the following chains: Sierra de los Ladrones, Mount Taylor, Sierra Madre, 
Sierra de Jemez , Sierra de San Juan and the vi'estern mountains ol the South , Middle and North 
Parks. Their height varies from 8,000 to 11,000 feet. The last named chains form the dividing- 
ridge between the w'aters of the Atlantic and those of the Pacific ocean. 
The Wahsatch mountains forming the w'estern side of the Great Salt Lake, also belong to the 
system of the Rocky mountains; their elevation is from 5,000 to 8,000 leet above the level of the sea. 
The Sierra Blanca or Sierra de Mogoyon, the dilferent chains of which run from north-west 
to south-east, their heights varying from 10,000 to 14,000 feet, occupies the southern part of this 
central region. The Rio Gila, the Rio Colorado Chiquito , and Bill William Fork have their sources 
in this sierra. 
3°. The western or Pacific region begins where the high table lands ol the basin of the Ca- 
lifornian Rio Colorado meet one of the chains of the Sierra Nevada, and terminates at the Pacific 
