OF MINNESOTA. 169 
tion. A few boulders, here and there projecting above the water-level, in the more 
rapid parts of the stream, or occasionally in the banks, constitute all that meets the 
eye of the geologist. These are usually of granite, or some allied crystalline rock. 
After ascending Leaf River some forty-five or fifty miles, I detected, among the 
drift composing a ridge of seventy-four feet in elevation, a few fragments of lime- 
stone, containing obscure organic forms. These indicate an origin from some calca- 
reous formation to the north or northwest, belonging probably to the age of the 
Silurian rocks of Europe. They increased in number and size as we approached 
Otter Tail Lake. The indications on that lake were so abundant, that I was led to 
believe that the more angular fragments must have their origin at no very distant 
locality. No ledges could, however, be detected. The lake shore is lined, wherever 
the banks are high, with heavy beds of erratics, thrown together in indiscriminate 
confusion, and over which, in windy weather, the waves dash, flinging their spray 
high into the foliage of the overhanging trees and interlacing vines that fringe the 
bank, and find root in the scanty soil collected between the water-worn boulders. 
The banks of the Crow Wing are seldom over fifteen feet, and usually not more 
than five to ten feet high. The forest is composed of pine, birch, elm, and oak. 
The trees are mostly of small size. The largest pines which I observed, were from 
eighteen inches to two feet in diameter, but they are usually not more than from 
nine to twelve inches. The best pine forest near the river, is about twenty miles 
below the confluence of Leaf and Crow Wing, in latitude 46° 20’ 14”, according to 
our observations. About twenty-three miles up Leaf River, we arrived among 
groves of pine, which extended some four or five miles along the river. The trees 
appeared very uniform in size, but were mostly less than a foot through. 
The temperature of the water of Crow Wing River, on the 12th of June, at three 
o'clock Pp. M., was 67° Fah. The temperature of the air in the shade, was 66°; in 
the sun, 86°. The temperature of the water of Leaf River, at three P. M., on the 
14th of June, was 75° Fah.; of the air in the sun, at the same time, 90°. On 
the 16th of June, at ten A.M., the temperature of the water of the same stream 
was 71°. This was only about one mile from Leaf Lake, in which this stream 
takes its rise. The temperature of the air in the shade, at noon, of the same day, 
was 77°. 
Leaf River has a very circuitous course, for ten miles, through a tamerack swamp, 
after leaving Leaf Lake. It was with great difficulty that we could find, on this part 
of the river, ground solid enough to admit of landing. On the night of the loth, we 
were obliged to “run” till nine o'clock, before we found a bank sufficiently firm 
and dry to admit of pitching our tent. 
The head-waters of Leaf River have a sluggish current, but are nevertheless very 
clear, and afford some noble specimens of Planorbis corpulentus and Limnea mega- 
somus. 
At half past ten, on the morning of the 16th, we entered Leaf Lake. It is about 
three and a half miles long, by one mile wide, and is surrounded by low hills of 
drift. It communicates, by a very narrow channel, through which we had great 
difficulty in passing our canoes, with a second lake, of which the shores are some- 
what lower. From the northwest end, a portage of four to five hundred yards, 
22 
