374 Mr. J. Croll on Geological Time, and the probable 



have been approached during this voyage, many on board the 



f Ariel ' have been close to bergs heavily laden A man 



who has had some experience of ice has never seen a stone on a 

 berg in these latitudes. Captain Anderson of the 'Europa/ 

 who is a geologist, has never seen a stone on a berg in crossing the 

 Atlantic. No stones were clearly seen on this trip"*. Captain Sir 

 James Anderson (who has long been familiar with geology, has 

 spent a considerable part of his life on the Atlantic, and has 

 been accustomed to view the iceberg as a geologist as well as 

 a seaman) has never seen a stone on an iceberg in the Atlantic. 

 This is rather a significant fact. 



Sir Charles Lyell states that, when passing icebergs on the 

 Atlantic, he " was most anxious to ascertain whether there was 

 any mud, stones, or fragments of rocks on any one of these 

 floating masses ; but after examining about forty of them with- 

 out perceiving any signs of frozen matter, I left the deck when 

 it was growing dusk"j\ After he had gone below, one was 

 said to be seen with something like stones upon it. The 

 Captain and officers of the ship assured him that they had never 

 seen a stone upon a berg. 



There is still another point connected with icebergs to which 

 we must allude, viz. the opinion that great masses of the boulder- 

 clay of the glacial epoch was formed from the droppings of ice- 

 bergs. It is perfectly obvious that unstratified boulder-clay 

 could not have been formed in this way. Stones, gravel, sand, 

 clay, and mud, the ingredients of boulder-clay, tumbled all to- 

 gether from the back of an iceberg, could not sink to the bottom 

 of the sea without separating. The stones would reach the bot- 

 tom first, then the gravel, then the sand, then the clay, and last 

 of all the mud, and the whole would settle down in a stratified 

 form. But, besides, how could the clay be derived from icebergs ? 

 Icebergs derive their materials from the land before they are 

 launched into the deep, and while they are in the form of land- 

 ice. The materials which are found on the backs of icebergs are 

 what fell upon the ice from mountain tops and crags projecting 

 above the ice. Icebergs are chiefly derived from continental ice, 

 such as that of Greenland, where the whole country is buried 

 under one continuous mass, with only a lofty mountain peak 

 here and there rising above the surface. And this is no 

 doubt the chief reason why so few icebergs have stones upon 

 their backs. The continental ice of Greenland is not, like the 

 glaciers of the Alps, covered with loose stones. It is perfectly 

 plain that clay does not fall upon the ice. What falls upon the 

 ice is stones, blocks of rocks, and the loose debris. Clay and 



* Short American Tramp, pp. 77, 81, 111. 

 f Second visit, vol. ii. p.o(>7. • 



