454 A POPULAR EXPOSITION OF THE 
at other localities.* These drift-beds vary in thickness from a mere 
coating in some spots, to over 100 feet in others. In all places they 
rest upon denuded:surfaces. As a general rule, the lower beds consist 
of calcareous clays, frequently, if not usually, free from: boulders:;; 
whilst sand, gravels, and boulders, mixed here and: there. with. seams; 
of clay (mostly free from lime), make up the higher. portions; of the 
mass. The conditions under which these various matters: appear. to 
have been accumulated, will be referred.to presently. 
The Post-glacial deposits consist; like those of the true Drift epoch, 
of beds of clay, sand, and gravel, with here and there a few boulders; 
and they appear to have been derived in most: instances from, re-distri- 
buted: Drift materials. Hence they are often designated: by. the term 
of Modified Drift. In Canada, east of the gneissoid belt of the upper 
St. Lawrence, and throughout the New England States of the North- 
ern Union, these Post-glacial deposits contain marine and estuary. 
shells, referrible for the greater part, if not wholly, to species of mollusca 
now existing in the Gulf of the St. Lawrence, or along the coast. from. 
Labrador to Cape Cod. Shells of this kind, mixed with a. few other 
marine types (Balani, &c., see Parr IV), occur at various heights 
above the sea-level, extending, as regards Canada, up to about 500, 
feet. Some of the principal localities of their occurrence, comprise : 
Kemptville in Oxford Township, Grenville Co. (about 250 ft.) ; Win- 
chester Township, Dundas Co. (about 300 ft.) ; Kennyon and Lochiel 
Townships, Glengarry Co. (270-300 ft.) ; Fitzroy Township on the 
Upper Ottawa, Carleton Co. (360 ft.) ; Green’s Creek on the Ottawa, 
(about 120 ft.) ; Montreal Mountain (various heights up tonearly 500 
feet), and environs of Montreal generally; Upton, Eastern Townships 
(about 270 ft.); Beauport near Quebec. (about 120 ft.); Mouth of 
the River Gouffre (130-360 ft.); Shore of the River Matanne in 
Gaspé (about 50 ft.) ; Banks of the River Métis (130-245 ft.) ; and 
terraces of the River Ste. Anne and Riviére du Loup. At Green’s 
Creek on the Ottawa, the shell beds contain, also, examples of the 
capelin (Mallotus villosus) and the lump-sucker (Cyclostomus lum- 
pus); and the remains of the northern seal (Phoca Grenlandica), with 
detached vertebrae of a whale, have been discovered in the Montreal 
deposits. 
Professor Dawson divides. the Eastern Post-glacial beds into. two 
* As regards localities in Western Canada, see papers by the author, in Canadian Jour 
nat: vol. V. p. 41; and vol. VI. p. 221, 
