
BRITISH NORTH AMERICAN BOUNDARY COMMISSION. 

REPORT ON GEOLOGY, BOTANY, &e. 

CHAPTER I. 
PHYSICAL GEOGRAPHY AND GENERAL GEOLOGY. 
GENERAL PuysicaL Grograpuy.—Interior region of the Continent—Eastern boun- 
dary—Western boundary—Slope of the region—First prairie level—Second 
prairie level—Third prairie level—Transverse watersheds—Description of the 
southern transverse watershed—The northern transverse watershed—Areas 
drained by different river systems—Area of the plains. GENERAL OUTLINE 
OF THE GEOLOGY.—General nature of the region—Silurian series— Devonian 
series—Possible existence of Carboniferous rocks—Permian and Triassic— 
Jurassic—Cretaceous formation—Lignite ‘Tertiary formation—Authorities on 
the Geology of the region. 
‘ 

General Physical Geography. 
1. The great region of plain and prairie which occupies the whole of 
the central part of the United States and British America, where it crosses 
the forty-ninth parallel, is included in longitude between the 96th and 
114th meridians. It narrows rapidly northward, chiefly by the encroch- 
ment on it of its eastern border, and is limited to the north by the skirt 
of the coniferous forest, which nearly follows the line of the North 
Saskatchewan River. This great inland plain has an area in British 
America, between the forty-ninth and fifty-fourth parallels, of about 
295,000 square miles. 
2. Its eastern boundary is the slope of the old crystalline nucleus of 
the continent, which extends north of the River St. Lawrence and the 
Great Lakes, from Labrador to the Lake of the Woods, and, then turning 
suddenly at an angle of about sixty degrees to its former general direction, 
runs with a north-north-west course to the Arctic Ocean, where it is 
described as appearing along the coast-line for some four hundred miles. 
The crystalline and highly metamorphic rocks forming this axis, are 
mostly referable to the Laurentian formation; but, no doubt, include 
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