20 



RED RIVER EXPLORING EXPEDITION. 



Changes in lake levels are important physical pheno- 

 mena in the basin of Lake Winnipeg. The rise or fall of 

 a few feet in Lakes Maintobah and Winnipego-sis deter- 

 mines the character of an immense area of country on the 

 low shores of those great inland lakes. Many hundred 

 square miles of splendid pasturage are accessible at low 

 lake levels, which are converted into marshes or swamps 

 during periods of high water. The shores of the Great 

 Canadian Lakes are generally high, and are not affected 

 by a rise or fall of a few feet. The following additional 

 notices of extraordinary changes in lake levels, which 

 have occurred in the St. Lawrence valley, may tend to 

 throw some light upon similar phenomena in the valley of 

 Lake Winnipeg during recent periods. 



From 1788 to 1790, the lakes generally, and Lake Erie 

 in particular, are stated to have been as high as in 1838 

 (5 ft. 3 in. above zero). Professor Hall mentions evidence 

 of a higher level than in 1838, as recorded by ridges and 

 submerged trees. 



In 1819 and 1820, the central and lower lakes are 

 described as being unusually low. Lake Superior in 1827 

 and 1828 was lower than ever before known. In 1838 

 Lake Erie was 5 ft. 9 in. higher during the month of 

 August than in 1819. Much land was overflowed, and 

 trees of 100 years' growth destroyed. 



In October, 1849, the water level of Lake Ontario was 

 at a minimum ; in June, 1853, it was 4 feet 5 inches 

 above the minimum. In the winter of 1855 it again 

 sank to the minimum ; and during the summer of 1858 

 the rise amounted to 4 feet 3 inches. No less than 40 

 inches, or 3 feet 4 inches, of this rise in the mean level 

 was attained during the summer of 1858. 



As the result of observations extended over twelve 

 years (1846 to 1857) in the variations of the level of Lake 

 Ontario, the following facts have been established : — 



