No. 1.] DAWSON — POST-PLIOCENE. 25 



but I have observed in Cape Breton a peaty or brown coal 

 deposit, with branches of coniferous trees, to underlie it, and in 

 other places there are deposits of rolled gravel under the Boulder- 

 clay. At the Glen brick-work, near Montreal, a peculiar modified 

 Boulder-clay occurs, consisting of very irregularly bedded sand 

 and gravel, with many large boulders, and only thin layers of 

 clay. 



The stones of the Boulder-clay are often scratched and ground 

 into those peculiar wedge-shapes, so characteristic of ice-worked 

 stones. Very abundant examples of this occur in the Boulder 

 clay of Montreal and its vicinity. 



At Isle Verte, Biviere du Loup, Murray Bay, Quebec, and St. 

 Nicholas, on the St. Lawrence, the Boulder-clay is fossil iferous, 

 containing especially Leda truncata, and often having boulders 

 and large stones covered with Balanus Hamerl and with Bryozoa, 

 evidencing that they have for some time quietly reposed in the 

 sea bottom before being buried in the clay. This is indeed the 

 usual condition of the Boulder-clay in the lower part of the St. 

 Lawrence Biver. Further up, in the vicinity of Montreal, it 

 has not been observed to contain fossils, but it presents equally 

 unequivocal evidence of sub-aqueous origin in the low state of 

 oxidation of the iron in the blue clay, which becomes brown when 

 exposed to the weather, and in the brightness of the iron pyrites 

 contained in some of the glaciated stones, as well as in the pre- 

 sence of rounded and glaciated lumps of Utica shale and other 

 soft rocks, which become disintegrated at once when exposed to 

 weathering. 



The true Boulder-clay is in all ordinary cases the oldest mem- 

 ber of the Post-pliocene deposits, and it is not possible to ascer- 

 tain the existence of Boulder-clays of different ages, superimposed 

 on one another. It may be observed, however, that in so far as 

 the Boulder-clay is a marine deposit, that which occurs at lower 

 levels is in all probability newer than that which occurs at higher 

 levels. It is also to be observed that boulders with layers of 

 stones occasionally occur in the Leda clay ; and that the super- 

 ficial sands and gravels sometimes contain large boulders ; but 

 these appearances are not, I think, sufl&ciently important to induce 

 any experienced observer to mistake such overlying deposits for 

 the true Boulder cla v. 



In some localities the stones in the Boulder-clay are almost 

 exclusively those of the neighbouring rock formations, and this is 



