94 Sir Charles Lyell [April 27, 



drift, boulders, and glacial furrows in the neighbourhood of the 

 Falls of Niagara, both in Canada and in the State of New York,* 

 to show that the whole region, with its elevated platforms and 

 its valleys, had first gone down gradually, and had then been re- 

 elevated during the glacial period. All geologists who are 

 acquainted with Berkshire, Massachusetts, are agreed that the 

 position of the erratics cannot be explained by the subsequent 

 unequal elevation of the mountain ranges, as if B, for example, had 

 been uplifted to a greater height than A, after the great boulders 

 had been stranded on B. It is clear that the ridge B has inter- 

 cepted many erratics on its north-western side, as it would do now, 

 if submerged, and the blocks have chiefly crossed through gaps 

 or depressions in B. The glacial furrows also are such as would 

 be made on the fixed rocks, after they had already assumed their 

 actual position, and when the present hills and valleys existed. 



Although the principal mass of drift had accumulated before the 

 trains, yet we see some of the biggest blocks partially buried in 

 drift. This we might have expected, according to the hypothesis 

 above suggested, for coast-ice, such as forms annually in the Gulf 

 of St. Lawrence and along the coast of Labrador, does not merely 

 bear away great stones but also mud, sand, and gravel. 



The speaker exhibited a drawing of a large angular block of 

 sandstone, about eight feet in diameter, which he and Mr. J. W. 

 Dawson saw in 1852, stranded on the mud-flats near the mouth of 

 the Petitcodiac estuary, where it joins the Bay of Fundy, and where 

 the water is salt. The ferrymen stated that this block was brought 

 down by ice three years before, from a cliff" several miles up the 

 river. About the year 1850 much larger blocks of sandstone were 

 removed by coast-ice from the base of a perpendicular cYi^ at the 

 South Joggins, in the Bay of Fundy, in salt water, and floated for 

 about half a mile, where they dropped or were grounded on one 

 side of the pier built for loading vessels with coal. The vessels being 

 thereby prevented from nearing the pier it was found necessary to 

 blast these ice-borne rocks, at low tide, with gunpowder. All this 

 occurred in latitude 46^ N., corresponding to that of Bordeaux ; and 

 when we bear in mind that the Bay of Fundy opens towards the 

 south, and is therefore never invaded by icebergs, such as are 

 stranded occasionally near St. John's, Newfoundland, or such as are 

 annually drifted far to the south of the Bay of Fundy in the open 

 ocean, we may well imagine that, with a different configuration of 

 the land, coast-ice may once have exerted great power as far south 

 as the latitude of Berkshire. The buoyant power of sheets of 

 ice, even of moderate thickness, is so great that the magnitude of 

 erratics depends more on the dimensions of the fragments into 

 which rocks undermined by the sea happen to split, than on the 

 peculiar intensity of the frost in that region. 



* "Travels in North America," Vol. I., p. 99 ; and Vol. II., p. 48. 



