PRELIMINARY REMARKS. 
31 
are belted by a sandy desert some 400 or 500 miles wide, which 
is prolonged northward to the mouth of the McKenzie river, a 
distance of 1500 miles. 
The coast range of the Pacific, and the Sierra Nevada, are 
parallel chains, and separated by the valley of San Joachim 
and San Francisco. These ranges, prolonged into Oregon, are 
succeeded by the Cascade mountains. These three ranges fre¬ 
quently rise above the line of perpetual snow. The outer range 
is only 380 miles from the Pacific ocean. Considered as conti¬ 
nental ranges, their slope is towards the Atlantic, and the 
counter slope to the Pacific. They are in the ratio of two to 
one. The great valley and its slopes drained by the Missis¬ 
sippi, and its thirty-four navigable rivers, contain an area of 
3,245,000 square miles. The Mississippi trunk is navigable to 
the falls of St. Anthony, and the Missouri high up the waters 
of the Yellow Stone. 
§ 28. The Lawrentine chain is comparatively low, not ex¬ 
ceeding 2500 feet. It is but little known. It divides the 
waters of the St. Lawrence, the Mississippi, and the rivers of 
the British territories. The chain varies but a few degrees 
from east to west. 
A small mountainous tract lies north of the Mohawk, between 
the St. Lawrence and Lake Champlain. The four distinct 
ranges by which this tract is traversed are parallel with each 
other. Their axes are directed to the north-east. The main 
chain rises at Little Falls, and pursuing a north-east course, 
terminates abruptly at Trembleau point on lake Champlain. 
The culminating point of this range is mount Marcy. This 
mountain is the center of the Adirondack group, and rises to 
the height of 5467 feet. From this group the drainage is com¬ 
posed of the Ausable, Saranac, Racket, Black, and the branches 
of the Hudson river. The lakes situated upon the table land, 
and from which these rivers rise, are from 1500 to 1800 feet, 
this level is about the same as that of Connecticut lake, and 
not greatly inferior to the lakes which give origin to the Mis¬ 
sissippi. 
