Notices of Books. 
271 
1876.] 
the wonderful elevation of New Mexico, Colorado, and 
Wyoming, in which the lowest town is situate at the extraordi- 
nary height of 4000 feet above the sea-level, whilst the highest 
— Montgomery, in Colorado-— -exceeds 11,000. The only error 
we perceive is in the height of Vesuvius, which, probably by a 
typographical error, is given as 8479 feet. 
An Essay concerning Important Physical Features exhibited in 
the Valley of the Minnesota River , and upon their Signifi- 
cation . By G. K. Warren. Washington : Government 
Printing Office. 
The author argues that Lake Winnipeg was at one time vastly 
larger than at present. At that period it discharged its waters, 
not as at present by the Nelson into Hudson’s Bay, but by the 
Minnesota into the Mississippi ; the Canadian lakes flowing, 
also, through Lake Michigan and the Illinois River, in the same 
direction. In support of this view he argues that the Nelson 
River and also the St. Lawrence bear, in their numerous rapids 
and falls, every mark of a comparatively recent origin. The 
Valley of the Minnesota, above its junction with the Mississippi, 
is out of all proportion too large for the former stream in its 
present condition, and only becomes intelligible if we consider 
it as the main artery of a vast tradl of country. The Valley of 
the Illinois likewise appears disproportionate to the size of that 
river in modern times. These changes he accounts for by the 
assumption of a general subsidence of the land in the northern 
and eastern parts of the North American continent. By this 
change a new vent was opened for the waters of Lake Winnipeg 
and of the Canadian lakes, thus forming respectively the Nelson 
and the St. Lawrence, whilst the Minnesota and the Illinois, de- 
prived of their main feeders, shrank into streams of an inferior 
rank. 
The work is illustrated by several plans, and by a map showing 
the restoration of the ancient basin of the Mississippi. In this 
map the river is represented as rising in about lat. 56° N. and 
long. 40° W., draining the regions west of Hudson’s Bay, passing 
through Lake Winnipeg, which then covered in all probability an 
area far exceeding that of Lake Superior, receiving the overflow 
of the Canadian chain through the Illinois, and falling finally 
into an estuary which penetrated to the influx of the Missouri. 
The evidence in support of the author’s theory has been very 
carefully collected, and is presented with great clearness. 
