382 



cated to me several interesting facts observed by him both on the 

 lakes of Canada and in the St. Lawrence. In the river last men- 

 tioned the loose ice, when the water is low in winter, accumulates 

 on the shoals, the separate fragments being readily frozen together 

 into solid masses in a climate were the temperature is sometimes 

 20° below zero. In this ice boulders become entangled, and in the 

 spring, when the river rises after the melting of the snow, the packs 

 are floated off, frequently conveying away the boulders to great di- 

 stances. Heavy anchors of ships lying on the shore have in like 

 manner been closed in and removed. He also states that immense 

 ice-islands, detached far to the north, perhaps in Baffin's Bay, are 

 brought by the current in great numbers down the coast of Labrador 

 eveiy year, and are frequently carried through the Straits of Belle- 

 isle between Newfoundland and the continent of America, which, after 

 passing through the Straits, sometimes float for several hundred 

 miles to the south-west up the Gulf of St. Lawrence. In one of 

 these icebergs which Capt. Bayfield examined, he found heaps of 

 boulders, gravel, and stones, and he saw other ice-floes discoloured 

 by mud. Capt. Belcher also informs us that in 1815, when in 

 His Majesty's ship Bellerophon he fell in with field-ice off New- 

 foundland, near St. John's Harbour, in which there were muddy 

 streaks, gravel, and even stones : it was in the heat of summer and 

 torrents of water were shooting off the ice. The importance of these 

 phasnomena will be duly appreciated by the geologist who reflects 

 that they relate to the annual transportation of rocks from high la- 

 titudes probably corresponding- to those of the northern parts of 

 Norway and Sweden, and that the points sometimes reached by the 

 ice are further south than any part of Great Britain. It is there- 

 fore by no means necessary to speculate on the former existence of a 

 climate more severe than that now prevailing in the Western Hemi- 

 sphere in order to explain how the travelled masses in Northern 

 Europe may have been borne along by ice. We know from inde- 

 pendent evidence that large parts of the lands bordering the Baltic, 

 and now strewed over with erratics, have constituted the bed of the 

 sea at a comparatively modern period. 



It may be asked whether I refer all erratics, even those of Swit- 

 zerland and the Jura, to the carrying power of ice. In regard to 

 those of Switzerland I have elsewhere endeavoured to show that a 

 combination of local causes might have contributed to their transfer ; 

 for repeated shocks of earthquakes may have thrown down rocky 

 fragments upon glaciers, causing at the same time avalanches of 

 snow and ice, by which narrow gorges would be choked up and 

 deep Alpine valleys, such as Chamouni, converted into lakes. In 

 these lakes, portions of the fissured glaciers, with huge incumbent 

 or included rocks might float off, and on the escape of the lake, 

 after the melting of the temporary barrier of snow, they might be 

 swept down into the lower country*. 



M. Charpentier has lately proposed another theory which he in- 



« Principles of Geology, vol. iii. p. 149, 1833, enlarged in later editions. 



