252 ASSINNIBOINE AND SASKATCHEWAN EXPEDITION. 



There can be no doubt that a very large portion of the 

 drift of Canada has been rearranged since it was first de- 

 posited. The inferior layer of blue clay is, however, 

 essentially different from the upper layer which is fre- 

 quently separated from it by a few feet of sand, and in 

 some instances may even directly overlie it and consist of 

 a rearrangement of its materials. The superior blue clay, 

 together with the sand and yellow clay, frequently give 

 evidence of stratification, and thus explain at once the 

 nature of the force to which they have been subjected. 



The position of the rock fragments in the inferior blue 

 clay, proves that it cannot have been exposed to the 

 action of water, otherwise they would not preserve the 

 forced arrangement which distinguishes them. Frag- 

 ments of shale, if submitted to gravity alone, would not 

 have assumed the position in which they were found, had 

 they dropped through water in motion or water at rest, 

 into soft mud. It is well known that shingle, sand, 

 gravel, and clay, either separately or combined, when 

 thrown down an incline, as in the construction of a rail- 

 way embankment or as in a land slip, will assume a po- 

 sition upon the surface of the embankment, which, if 

 composed of sand, is generally inclined about 45° ; if 

 of harder or coarser materials, at a higher angle. If the 

 embankment or incline be formed under water, like the 

 deltas at the mouths of rivers, this inclination is much 

 less, and is dependent upon the specific gravity of the 

 materials, but under no circumstances is it so high as 45°. 

 If the existence of a current of water sufficiently powerful 

 to move masses of shale and boulders of the unfossili- 

 ferous rocks, it cannot be supposed that they would 

 be found deposited upon the slope of a bank at so 

 high an angle as the shale and boulders in the blue 



