296 ASSINNIBOINE AND SASKATCHEWAN EXPEDITION. 



On the low banks which are constantly wearing away, 

 and revealing fresh surfaces at points or bends, some well 

 stratified layers of a brown-coloured deposit, two feet 

 thick, appear about four feet from the present prairie 

 level. They resemble stratified bands of certain varieties 

 of bog iron ore, but a very slight examination is sufficient 

 to show that they are of vegetable origin. They consist 

 of a series of accumulations of buffalo dung, collected 

 doubtless by rains and floods from a considerable area, 

 and deposited in the low part of the Souris valley, which 

 lies to the south of the Sand Hills. A geological for- 

 mation composed of bois de vache is a novelty not likely 

 to be met with anywhere but on the continent of North 

 America. 



On the 2nd of July we observed the grasshoppers 

 in full flight towards the north, the air as far as the eye 

 could penetrate appeared to be filled with them. They 

 commenced their flight about nine in the morning, and 

 continued until half-past three or four o'clock in the 

 afternoon. About that hour they settled around us in 

 countless multitudes, and immediately clung to the leaves 

 of grass and rested after their journey. On subsequent 

 days, when crossing the great prairie from Eed Deer's 

 Head Eiver to Fort Ellice, the hosts of grasshoppers were 

 beyond all calculation ; they appeared to be infinite in 

 number. Early in the morning they fed upon the prairie 

 grass, being always found most numerous in low, wet 

 places where the grass was long. As soon as the sun 

 had evaporated the dew, they took short flights, and as 

 the hour of nine approached, cloud after cloud would rise 

 from the prairie and pursue their flight in the direction 

 of the wind, which was generally S.S.W. The number 

 in the air seemed to be greatest about noon, and at times 

 they appeared in such infinite swarms as to lessen per- 



