Drift ill Minneapolis, Minn. — UpJiam. 297 
Boulders up to 2 or 3 feet in diameter occur somewhat fre- 
quently on the hills near the Washburn Home ; and their ma- 
terial, as seen in sections, is partly till, but more of it is irregu- 
larly stratified coarse esker gravel and sand. In other parts 
of the series boulders are very rare or altogether absent, and 
the material is wholly modified drift. 
The Chain of Lakes. 
Within the southwestern limits of Minneapolis, Cedar lake, 
the Lake of the Isles, and lakes Calhoun and Harriet, each 
about a mile long and ranging from a half mile to nearly one 
mile in their greatest widths, extend three miles and a half from 
north to south in a noteworthy series, or chain, as it is fre- 
quently called. Westward from these lakes, at least four or 
five miles, to St. Louis Park and Hopkins, a surface of nearly 
level but broadly undulating modified drift, stratified gravel 
and sand deposits, continues, rising to 920 and 930 feet above 
the sea in its higher portions. The chain of lakes, however, 
is succeeded in its line of continuation northward by a promi- 
nently hilly marginal moraine of till, before described, which 
stretches from the west side of Cedar lake four miles north to 
Crystal lake, with hills rising to 925 to 975 feet above the sea. 
At the same time with the formation of those morainic hills at 
or beneath the east edge of the ice-sheet, apparently the con- 
tinuation of this edge occupied the place of the chain of lakes, 
while the modified drift plains 25 to 50 feet above the lakes at 
their east side were being deposited. The ascent from the 
water to the plain is a steep slope, such as is attributed to abut- 
tal of a sand plain, during its formation, against an ice barrier. 
To the height of the plains above the lakes, we must add 
the depth of the water to give the measure of the basin below 
the gravel and sand level. Soundings by Mr. Frank H. Nut- 
ter, city park engineer, show that the Lake of the Isles is most- 
ly only 8 to 12 feet deep, but has two hollows of small area, ly- 
ing one east and the other west of the island, which sink, re- 
spectively, 40 and 42 feet beneath the water surface. (In the 
improvement of this lake by dredging and remodeling its 
shores, as a part of the system of city parks and boulevards, 
two other islands formerly existing have been made parts of 
the mainland.) Full soundings of the other lakes have not yet 
