OF MINNESOTA. 



1G9 



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 Avere 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 p. m., was G7° 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 ( (°. 



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 15th, 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- 

 sornus. 



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. 



