CHAP. xvin. FLOATING OF BOULDEES ON ICE. 361 



c, and the intervening valleys, the hypothesis of glaciers is 

 out of the question. I conceive, therefore, that the erratics 

 were conveyed to the places they now occupy by coast ice, 

 when the country was submerged beneath the waters of a 

 sea cooled by icebergs coming annually from arctic regions. 



Fig. 53 



N.W. 

 Canaan 



d, e Masses of floating ice carrying fragments of rock. 



Suppose the highest peaks of the ridges A, B, c, in the an 

 nexed diagram, to be alone above water, forming islands, and 

 d e to be masses of floating ice, which drifted across the Canaan 

 and Eichmond valleys at a time when they were marine 

 channels, separating islands, or rather chains of islands, having 

 a NNE. and SSW. direction. A fragment of ice such as 

 f/, freighted with a block from A, might run aground, and add 

 to the heap of erratics at the NW. base of the island (now 

 ridge) B, or, passing through a sound between B and the next 

 island of the same group, might float on till it reached the 

 channel between B and c. Year after year two such exposed 

 cliffs in the Canaan range as d and e of the map, fig. 50, 

 p. 357, undermined by the waves, might serve as the points of 

 departure of blocks, composing the trains Nos. 5 and 6. It 

 may be objected that oceanic currents could not always have 

 had the same direction ; this may be true, but during a short 

 season of the year when the ice was breaking up the prevailing 

 current may have always run SE. 



If it be asked why the blocks of each train are not 

 more scattered, especially when far from their source, it may 

 be observed, that after passing through sounds separating 

 islands, they issued again from a new and narrow starting 



