274 B. Chalmers — Pre- Glacial Decay of Rocks. 



An ample field for the study of rock-decay and of the differ- 

 ent agencies by which it is effected exists in Canada, in which 

 few workers have yet been found. In the eastern portion, 

 previous to 1882, when the writer began investigations in the 

 surface geology of the Maritime provinces, only two geologists 

 were known to have observed phenomena of this kind. Sir 

 J. W. Dawson had noted decomposed slates at Les Eboule- 

 ments on the north side of the St. Lawrence below Quebec;* 

 and Dr. T. S terry Hunt observed the products of rock-decay 

 on the south side of Mount Royal, at Montreal, and also at 

 Rigaud Mountain in Yaudreuil.f In these and other places, 

 e. g., Ste. Anne de Beaupre, Charlesbourg near Quebec, Port- 

 neuf, Lachute, etc., the materials in question lie at the southern 

 base of ridges or hills and have escaped the eroding action of 

 the Pleistocene ice. Since the date above mentioned the 

 writer has collected a considerable body of facts relating to 

 this subject in the eastern portion of Canada to which refer- 

 ence has been made in reports on the surface geology of New 

 Brunswick, JSTova Scotia and Prince Edward Island in the vol- 

 umes since published by the Geological Survey of Canada, In 

 the present paper an attempt is made to collect together the 

 results of the scattered observations of these years and draw 

 the attention of geologists to these ancient and very interesting 

 products of rock-decay which seem to be the only remnants 

 now in existence here representing the long ages which elapsed 

 between the Carboniferous, or rather the Triassic, and the 

 Pleistocene. 



The question of rock-decay in the geological ages which 

 preceded the Tertiary, however, is not here considered. No 

 remnants of such, as distinct from those of later ages, have 

 been recognized in the region under discussion. But it is pos- 

 sible they do exist, though indistinguishable from those of 

 Tertiary age. Fossil evidence is, so far, entirely wanting in 

 the pre-glacial decayed rock materials of Eastern Canada. 



Definition of Terms. 



Preliminary to a discussion of the pre-glacial decayed rock 

 materials, it is, perhaps, desirable to explain and define certain 

 terms employed in this paper regarding them. The materials 

 in question have been found to be principally of two classes — 

 sedentary and modified. The term sedentary is nsed to desig- 

 nate all those portions of the rock surface of the region which 

 have decomposed in situ whether to greater or less depths, and 

 which, although now in the form of loose gravel, sand, etc. 



* Notes on the Post-Pliocene Geology of Canada, Can. Naturalist, 18T2. 

 fThis Journal, vol. xxvi, 1883, pp. 208-209. 



