118 N. H. WINCHELL GLACIAL LAKES OF MINNESOTA 



Mississippi valley as far as Monticello, in Wriglit county ; but at the 

 moment of its greatest extension it was also at the epoch of its greatest 

 peril as a lake, a statement which can also be made, probably, of all 

 glacial lakes, for it required but little recession of the ice-border east- 

 ward from Mendota to lower the level of the whole lake by exposing a 

 lower outlet. Its first important outlet was through the central part of 

 Dakota count}^ where a distinct, wide, 2;ravel-terraced valley extends 

 from Crystal lake southeastward and connects with the Vermilion river, 

 which discharges into the Mississippi at Hastings. There are other 

 similar avenues of glacial drainage farther south, in Dakota county, and 

 they ma}'' have served as exit for the waters of lake Shakopee in its ear- 

 liest stages, before it acquired definite characters, and perhaps while the 

 margin of the western ice-lobe took part in giving this lake its north- 

 western limitation, but the}^ are hardly worth 3^ of separate definition as 

 outlets of distinct glacial lakes. 



8. Lake Hamline 



Mr Upham has described this lake in the bulletin of the Society.* It 

 was a small lake, confined to a small county (Ramsey), and had a brief 

 existence. It was typically an interlobate lake, and existed slightly 

 prior to lake Shakopee. Its elevation was about 940 feet at first, with 

 an outlet northward, but was soon shifted to about 880 feet, with dis- 

 charge through Inver Grove, in Dakota count}', where it united with 

 one of the later outlets of lake Shakopee. It seems to have suffered by 

 the opening of lower and lower avenues of discharge until it was low- 

 ered to the level of lake* Shakopee and was wholly lost as an independ- 

 ent lake. It is further probable that the outlets of both lake Hamline 

 and lake Shakopee were occasionally disturbed and shifted in part by 

 the presence of the gorge of the Mississippi at Saint Paul. It is reason- 

 able to suppose that the variations of the glacier where its margin 

 extended north and south across that gorge would afford escape for 

 considerable water from time to time down that valley past Saint Paul. 

 This would occur most frequently during the later portion of the exist- 

 ence of these lakes. The washed drift of lake Hamline is rather coarse, 

 and it sometimes embraces unwashed small pieces of till which indicate 

 the proximity of the ice-margin at the time of deposition of the gravel. 



9. Lake Mahtomedi 



Lake Mahtomedi covered the region of White Bear lake, in Ramsey 

 county, and extended north into Washington and Anoka counties, hav- 



* op. cit., vol. viii, p. 193, pi. 15. 



