Ch. XVI] 



COAST-ICE. 



o o o 



GOO 



momentum 



The 



same berg is often carried away by a change of wind, and 

 then driven back again upon the same bank, or it is made to 



i 



ise and fall by the waves of the ocean, so that it may alter- 



bottom 



lifted np again, until it has deranged the superficial beds 



over a wide area. 



may 



perhaps, for the circumstance that in Scandinavia, Scotland, 

 and other countries where erratics are met with, the beds of 

 sand, loam, and gravel are often vertical, bent, and contorted 

 into the most complicated folds, while the underlying strata, 

 although composed of equally pliant materials, are horizontal. 

 But some of these curvatures of loose strata may also have 

 been due to repeated alternations of layers of gravel and 

 sand, ice and snow, the melting of the latter having caused 

 the intercalated beds of indestructible matter to assume their 



omalous 



• i • 



must 



off the peaks and projecting points of submarine mountains, 

 and must grate upon and polish their surface, furrowing or 

 scratching them, and reducing them to domeshaped masses, 

 in precisely the same way as we have seen that glaciers act 

 on the solid rocks over which they are propelled.* 



Coast-ice. — It appears, then, that large stones, mud, and 

 gravel are carried down by the ice of rivers, estuaries, and 

 glaciers, into the sea, where the tides and currents of the 

 ocean, aided by the wind, may cause them to drift for hun- 

 dreds of miles from the place of their origin. But we have 

 not yet considered the transporting agency of coast-ice, w^hich 

 is often very active on the shores of the ocean far from the 

 points where rivers enter. 



The saline matter which sea-water holds in solution, pre- 

 vents its congelation except where the most intense cold 

 prevails. But the drifting of the snow from the land often 

 renders the surface water brackish near the coast, so that a 



* In my Travels in N. America, account of the action of floating ice and 



p. 19, 23, &c, and Second Visit to the coast-ice, and its bearing on geology, 



U. S., vol. i. ch. 2., also in my Elements will be found, 

 of Geology, 6th ed. p. 144, a more full 



