1856.] Physical Geography of North America. 169 



border of the elevated western plateau, is a broad well-watered 

 plain, full of streams and lakes, rising nowhere higher than 1500 feet 

 above the sea ; and in few districts higher than 500 or 700 feet. It 

 includes three large natural basins of drainage — that of the Missis- 

 sippi, and its affluents east of the high western steppes ; that of the 

 Lawrentian Lakes and their feeders ; and that of the southern, 

 western and eastern tributaries of Hudson Bay. 



1. The Mississippi Basin. — This wide river basin slopes so 

 gently southward that its height at the mouth of the Missouri, 

 nearly 700 miles from the sea, is only 388 feet ; and at the Falls of 

 St. Anthony, 1150 miles from the sea, it is no more than 856 feet. 

 Its eastern and western slopes are likewise extremely gentle, as 

 shown by the fact, that the elevation of the plain at Pittsburg, 

 nearly 600 miles from the Mississippi, eastward, is only 679 feet ; 

 and in the opposite direction, at the mouth of the republican fork of 

 the Kansas, it is still but 927 feet. The basin of the Mississippi and 

 Missouri is divided from that of Hudson Bay, — from the western 

 end of Lake Superior to the foot of the Rocky Mountains, but east- 

 ward from the drainage of the Lawrentian Lakes, — by a low water- 

 shed, nowhere higher than 1300 feet, and in few districts more than 

 1000 feet above the sea. This whole Mississippi plain enjoys a soil 

 and climate of rare fertility, and, possessing enormous coal-fields and 

 other mineral wealth, is endowed with extraordinary! agricultural, 

 commercial, and manufacturing resources. From the westeni slopes 

 of the Appalachians to the Mississippi, the "Wabash, and Lake 

 Michigan, nearly the entire surface was originally clothed with 

 forest ; but west of those limits, the vast plain consists of gently- 

 rolling verdant prairies, intersected by strips of woodland along the 

 valleys of the streams ; and on the south-west, sprinkled with parks, 

 and scattered clumps of trees. 



2. The- Lawrentian Lake Basin. — This middle basin, from the 

 head of Lake Superior to Lake Ontario and the Ottawa, is separated 

 on its south from the basin of the Mississippi and Ohio by the low 

 watershed bordering its lakes ; and on the north, from the southern 

 feeders of Hudson Bay by a somewhat higher watershed, ranging 

 from Missabay Heights, where the summit tract is about 1500 feet 

 high, north of Lake Superior and the Ottowa, and gradually declin- 

 ing to the sources of the Saguenay. It is a curious feature of this 

 basin, that its western rim is only 50 miles west of the head of 

 Lake Superior, the southern and northern watersheds which em- 

 brace it, uniting in about long. 92° 50'. An unusual portion of the 

 surface of this basin is covered with water. Its five great lakes con- 

 trast their magnitude with the smallness of the area which supplies 

 them ; for both the watersheds are in relatively close proximity to these 

 basins. In some districts the southern watershed is only a few miles 

 distant from Lakes Michigan and Erie ; while some of the streams 

 descending southward are more than 2000 miles from the Gulf of 

 Mexico. But this anomaly vanishes, when we recognise in these 



