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Dr. Forry on the Climate of the United States, Sf 



21 



try." Presuming that our readers are sufficiently well acquainted, 

 for the present purpose, with the physical features of the vast 

 region stretching from the Atlantic to the Pacific, and from the 

 Gulf of Mexico to the inland seas on our northern frontiers, the 

 descriptions will be limited to such parts alone as are essential. 



One of the most striking characteristics of the physical geogra- 

 phy of the United States, and which, it will be seen, induces the 

 most remarkable modifications of climate, is the existence of those 

 great inland basins of water which lie on our northern frontier. 

 Of so vast an extent are these ocean-lakes, that one of them 

 (Lake Superior) has a circuit, following the sinuosities of the 

 coast, of 1,750 miles. The basin of the St. Lawrence is truly a 

 region of "broad rivers and streams," containing, it is estimated, 

 an area of 400,000 square miles, of which 94,000 are covered 



with water. 



upenor 



the Gulf of St. Lawrence, the distance is about 1,900 miles. 



These ocean-lakes have been estimated to contain 11,300 cubic 



miles of water, — a quantity supposed to exceed more than half of 



all the fresh water on the face of the globe. The deepest chasms 



on the surface of either continent are presented perhaps by the 



depression of these lakes ; for though elevated near 600 feet 



above, the bottom of some is as far beneath, the level of the 



°cean. Lakes Huron and Michigan, which have the deepest 



chasms, have been sounded to the amazing depth of 1,800 feet 



without discovering bottom. 



The following table, which gives the mean length, breadth, 



e Ptn, area, and elevation of these several collections of water, 



1S taken from a recent report made by Douglas Houghton, Esq., 



Mich. & 



Collections of water. 



Lake Superior, 

 Green Bay, 

 Lake Michigan, 

 Lake Huron, 

 Lake St. Clair, 

 Lake Erie, 

 Lake Ontario, 

 {^StLawrence, 



Mean 



length 



in mi If 9. 



Mean 

 breadth 

 in miles. 



Mean 



depth 



in feet. 



Elevation above 



level of the sea, 



in feet. 



j 400 



80 



900 



100 



20 



500 



320 



70 



1000 



240 



80 



1000 



20 



18 



20 



240 



40 



84 



180 



1 35 



500 



1 



1 



20 



596 

 578 

 578 

 578 

 570 

 565 



232 



Area in 



square miles. 



32,000 



2.000 



22,400 



20,400 



360 

 9,600 



6,300 



940 





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