Ef INVESTIGATIONS IN MINNESOTA AND NORTH DAKOTA. 345 
north, which became a vasin that wouid remain filled with water, and 
it naturally follows that after this water-course had ceased to receive 
supplies from the north, the small amount of water that would escape 
from this lake, with its diminishing velocity, would not erode a granite 
bed sufficiently to rapidly reduce the depth of this lake. 
(2) The ancient shore line of Lake Traverse can be traced a mile 
below the present limit of the lake and would indicate a former union 
with Big Stone Lake since the days of active running water in this 
channel. The character of both the fauna and flora would bear out 
this theory, since the difference in vegetation in the valley and on the 
hillside is much more marked and pronounced between the lakes than 
itis below the foot of Big Stone Lake or above the head of Traverse 
Lake. Likewise the windings of the old bed of the Little Minnesota 
River would indicate little or no opposition from running waters. 
The similarity of species of fishes found in the two lake basins would 
indicate that these two lakes had at one time been connected and that 
there was free water communication between the parts, while the 
number of comparatively unimportant and minor differences (which, 
however, are quite noticeable and constant, and in some cases reach 
almost varietal importance) show clearly the landlocked condition of 
the fishes of Lake Traverse and amount almost to proof that these 
lakes have not been united in recent years.” 
LAKE TRAVERSE. 
Lake Traverse forms the greater part of the northwestern boundary 
of Traverse County, one of the western tier of counties in the State of 
Minnesota. It is a long, narrow body of water, varying from 1 to 14 
miles in width. The valley is of a regular trough shape, sloping from 
the top of the hills to the bottom of the lake. The water of the lake 
lies low in this trough, with but a narrow margin of level land between 
it and the steep hillsides. 
The lake is shallow, with a maximum depth of 30 feet and an average 
of possibly 15 feet, the depth fluctuating to the extent of 24 to 4 feet in 
periods of about four years. This variation is closely connected with 
the rainfall, but is said sometimes to happen without apparent cause. 
The lake at the time of our visit was about 3 feet deeper than it had 
been for four years. The water frequently falls so low that the large 
drift bowlders project from the surface of the water in the middle 
of the lake. The shore line is quite regular, marking a more than 
usual stony area in the drift. The water is warm, 77° at the time of 
our visit in July, and, owing to its shallowness and the high winds that 
‘stir the lake to its bed, the top and bottom temperatures are practically 
the same. The water is comparatively pure, never containing clay in 
‘Sufficient quantities to cause it to look turbid; it is soft and contains 
but little mineral salts. The hills on either side of the lake are 150 to 
200 feet high and composed entirely of drift, a greater part of which 
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