Glacial Lakes and Rivers in Sweden. — Up ham. 231 
when my earliest geological paper was published. Dr. N. O. 
Hoist, of the Geological Surve}wof Sweden, presented a closely 
similar theory to explain the formation of the eskers (asar) 
of that country.* We then were wholly unacquainted with 
each other, our conclusions, and the nearly similar earlier 
suggestion of Prof. N. H. Winchell on the same subject, f 
having been in each case reached quite independently. After- 
ward, in the recognition and mapping of glacial lakes, held 
by the barrier of waning ice-sheets, the first example in iVmer- 
ica somewhat completely traced and defined was the small 
lake Contoocook in the valley of the Contoocook river in 
New Hampshire, which I discovered while working under the 
direction of Prof. C. H. Hitchcock in the survey of that state. 
Within the subsequent twenty years the very large glacial 
lakes of the St. Lawrence basin, which before were partially 
defined by Newberry, N. H. Winchell, and others, have be- 
come more fully known by the explorations of Gilbert, Spen- 
cer, Taylor, Lawson, Leverett, and others, including the pres- 
ent writer; and the largest lake of this class, first recognized 
in 1872 as a glacial lake by Winchell, and named by me in 
1879 in honor of Louis Agassiz, I have specially mapped 
and described under the auspices of the geological surveys of 
Minnesota, the United States, and Canada. It was therefore 
a chief purpose in my travel through Sweden to observe and 
learn as much as possible concerning its hundreds of eskers, 
the ice-walled deposits of glacial rivers, and its scores of iden- 
tified glacial lakes that were pent up in the valleys between the 
western side of the departing European ice-sheet and the 
mountainous Scandinavian watershed. 
In its maximum extension, this ice-sheet, reaching out- 
ward from Scandinavia t.o London, Brussels, Dresden, 
Cracow, Kief, and Nijni Novgorod, covered an area of about 
2,000,000 square miles, including the basins of the Irish, 
North, Baltic, and White seas. Later its diminislied extent, 
when it had considerably retreated, is marked by the morainic 
Mecklenburg or Baltic ridge, its continuation in Denmark to 
Frederikshavn and the northwest coast, and, as I think, its far- 
*"Om de Glaciala Rullstensasarne," Geologiska Foreningens i 
Stockholm Fcirhandlingar, No. 31 (vol. Ill, pp. 97-112). 
tGeol. and Nat. Hi.st. Survey of Minn., First Annual Report, for 
18/2, p. 62. 
