460 Canadian Record of Science. 



region, and again, towards probably the close of the glacial 

 epoch, and subsequently, over the vast country east of the 

 Eocky Mountains, now occupied by the prairies, and 

 extending as far as the shores of Lake Winnipeg. The 

 eastern side of this lake, as I have shown in a previous 

 number of this journal, probably formed the eastern coast 

 of avast inland fresh water sea. There are ample evidences 

 on the prairies of more than one elevation and depression 

 and of the existence of vegetation, during the former. 

 Boulders, some of great size, have been transported 

 immense distances, and this can only be explained by the 

 action of icebergs floating, as at the present day, under the 

 influence of winds and currents. We can even now trace 

 the direction of the currents and of the prevailing winds in 

 those far distant times, as well as of the force which gra- 

 dually raised the land to its present level. In the great 

 prairie country occupying the southern central portion of 

 Canada, the greatest depression was at the base of the 

 Rocky Mountains, whilst the existence of great boulders 

 there of eastern origin, brought undoubtedly by icebergs, the 

 great areas of sand at and south of the sources of the River 

 Qu' Appelle, and the stretches of sand and the gravel ridges 

 southwest and west of Lake Manitoba, all prove that the 

 winds most prevalent, and probably the currents, were in a 

 direction somewhat south of west. The elevation of the 

 land to its present level was greatest at the Rocky Moun- 

 tains and least towards Lake Winnipeg, and this has 

 resulted in the flow of great rivers like the Saskatchewan 

 and Qu'Appelle being at the present day in a general east- 

 erly direction. The great depth of soil over such a vast 

 area as the north-west prairies, indicates either an im- 

 mensely longer period during which the mountains and 

 valleys to the northward were the subjects of erosion, or 

 that the process of erosion was of a more severe character 

 than in Ontario and Quebec, or that, in the latter pro- 

 vinces, subsequent depression under the ocean and inland 

 seas has resulted in the carrying away of much of the soil. 

 That there were inter-periods when the land was raised to 

 some extent from beneath the sea, and vegetation appeared 



