102 
INTRODUCTION. 
consists of the ranges known as the Rocky Mountains, 
running nearly parallel with the coast of the Pacific 
Ocean, of various elevation, but the highest peaks 
rising beyond the limits of perpetual frost and snow. 
These separate the waters running into the Pacific 
< Icean from those flowing into the Mississippi River, 
and Gulf of Mexico. The second system consists of 
the Appalachian ranges, which rise from an elevated 
table-land that makes up nearly half of their whole 
elevation, the summits occasionally reaching an altitude 
of six thousand, or even six thousand five hundred feet 
above the sea, but presenting a mean height of from 
two thousand to two thousand five hundred feet. They 
extend in a north-east and south-west direction from near 
the St. Lawrence river to Alabama, and form a barrier 
between the waters that flow westward to the Missis- 
sippi river and the Gulf of Mexico, and those that 
flow directly into the Atlantic Ocean. At their south- 
ern extremity they incline towards the south-west, and 
terminate before reaching the Gulf of Mexico, thus 
permitting the low alluvial lands of the southern Atlan- 
tic coast to unite with the lands of the same character, 
which form the southern part of the valley of the 
Mississippi. The great regions formed by these par- 
allel systems are the following : 
1. The Pacific Region, extending between the 
coast of the Pacific Ocean and the Rocky Moun- 
tains. Of this, as well as of the elevated plat- 
form or table-land from which these mountains 
