1864.] NATURAL HISTORY SOCIETY. 223 



cient summer heat to melt away tlie ice, except from high mountain- 

 peaks. Either then there must have been immense mountain- 

 chains which have disappeared, or there must have been some 

 unexampled astronomical cause of refrigeration, as, for example, 

 the earth passing into a colder portion of space, or the amount of 

 solar heat being diminished. But the former supposition has no 

 warrant from geology, and astronomy affords no evidence for the 

 latter views, which besides would iniply a diminution of evapora- 

 tion militating as much against the glacier-theory as would an 

 excess of heat. An attempt has recently been made by Professor 

 Frankland to account for such a state of things by the supposition 

 of a higher temperature of the sea, along with a colder temperature 

 of the land : but this inversion of the usual state of things is 

 unwarranted by the doctrine of the secular cooling of the earth ; 

 it is contradicted by the fossils of the period, which show that the 

 seas were colder than at present ; and if it existed, it could not 

 produce the effects required, unless a pr> ternatural arrest were at the 

 same time laid on the winds, which spread the temperature of the 

 sea over the land. The alleged facts observed in Norway, and 

 stated to support this view, are evidemly nothing but the results 

 ordinarily observed in ranges of hills, one side of which fronts cold 

 sea-water, and the other land warmed in summer by the sun. 



2. It seems physically impossible that a sheet of ice, such as 

 that supposed, could move over an uneven surface, striating it in 

 directions uniform over vast areas, and often different from the 

 present inclinations of the surface. Glacier-ice may move on very 

 slight slopes, but it must follow these ; and the only result of the 

 immense accumulation of ice supposed, would be to prevent motion 

 altogether by the want of slope or the counteraction of opposing 

 slopes, or to induce a slight and irregular motion toward the 

 margins or outward from the more prominent protuberances. 



It is to be observed, also, that, as Hopkins has shown, it is only 

 the sliding motion of glaciers that can polish or erode surfaces, 

 and that any internal changes resulting from the mere weight of a 

 thick mass of ice resting on a level surface, could have little or no 

 influence in this way. 



3. The transport of boulders to great distances, and the lodgment 

 of them on hill-tops, could not have been occasioned by glaciers. 

 These carry downward the blocks that fall on them from wasting 

 cliffs. But the universal glacier supposed could have no such 



