21^ INFLUENCE OF GEOLOGICAL STRUCTURE. 
jiiade up of a few wide and regular slopes ; on@ 
from the Appalachians westward to the Mississippi ; 
^mother, more uniform and far more extensive, froni 
the Kocky Mountains to the Mississippi ; and a third 
from the sources of the Mississippi and the great 
lakes north to the Arctic Sea. A very remarkable 
•feature of this region is the great uniformity of the 
whole surface, and the regular and gentle ascent 
from the Gulf of Mexico to the head-waters of the 
Mississippi, reaching in that space an elevation of 
not more than 1000 or 1200 feet, and again ascend- 
ing in a similar manner from the banks of the Mis- 
sissippi to the foot of the Rocky Mountains. Be- 
tween the Alleghanies and the Mississippi the sur^. 
iil^ce is broken into hills, and embraces the most fer- 
tile territory in the United States. About 400 miles 
west of the Mississippi a barren desert commences, 
which extends back to the Rocky Mountains, cover- 
ing a breadth of between 400 and 500 miles, and 
from Missouri, in latitude 56^, to Mexico. 
Influence of the Geological Structure of the United 
States upon its Inhabitants. — Professor Silliman re- 
marks,* that " it is perfectly apparent to geologists 
that the scenery of a country is not more exactly 
^tamped by its geological formations than are the 
rnanners and employments of its inhabitants. The 
bleak hills and long winters of New-England are un- 
favourable to the most extensive and profitable agri- 
cultural pursuits, while the extensive and deeply-in- 
dented seacoasts, abounding with harbours, head- 
lands, rivers, and inlets, naturally produce an im- 
pulse toward3 th,e ocean, which, conspiring with the 
original adventurous character of the population, 
sends them roving from the Arctic to the Antarctic 
Circje, till the wide world is laid under contribution 
by their enterprise. Their numerous streams and 
watjer-falls furnish |:he cheapest meg,ns for moving 
* Appen(iix to BakeweU's Geology, p. 483. 
