DEIFT ON THE PRAIKIES. 



249 



consequently posterior to that of the true Boulder drift, 

 which is generally distributed over the high prairies to 

 the west, and will be described further on in connection 

 with beaches and conical hills. 



On parts of the Little Souris Eiver the drift is very 

 shallow, indeed it is doubtful whether true Boulder drift 

 is present, the character of the surface material leading 

 to the supposition that it is derived almost exclusively 

 from the subjacent rocks. 



The drift on the South Branch of the Saskatchewan, 

 below the Moose Woods, is distinguished by a remarkable 

 peculiarity in the arrangement of the slabs of limestone 

 and boulders of the unfossiliferous rocks distributed 

 through the clay, which do not occupy the position they 

 would assume if dropped from floating ice into soft 

 mud. 



Every fact relating to the drift possesses some degree 

 of interest, and may assist in the elucidation of that 

 stupendous phenomenon and its subsequent changes, as 

 well as tend to remove difficulties with which the whole 

 phenomena of the drift are still invested.* 



In the blue clay at Toronto, the capital of Western 

 Canada, an arrangement similar to that which exists 

 among the coarser materials of the drift on the South 

 Branch is remarkably well preserved. 



During the construction of the esplanade at Toronto, the 

 plan pursued of removing the blue clay was well adapted 



* The forced arrangement of blocks of limestone, slabs of shale and un- 

 fossiliferons boulders in the blue clay of Toronto, formed the subject of a 

 paper which I read before the Canadian Institute some years ago. As the 

 opportunities for making observations upon this peculiar arrangement were 

 very favourable at that time, I shall here introduce an abstract of the paper, 

 with a view to explain the manner in which slabs and boulders are found 

 arranged in the Drift on the South Branch. (See Keport on the Assin- 

 niboine and Saskatchewan Exploring Expedition, p. 120.) 



