434 Probable iiifiuence of 



-whose centre was occupied by a very high peak covered with 

 ice. The shores were covered with scoriae and volcanic 

 ashes, which appeared as if they had been recently deposited ; 

 for in some places smoke or gas was seen escaping. They 

 dug into the scorice and sand to the depth of a foot or 

 more, to find the source of the smoke, and found that the 

 scoriae and sand were but a superficial covering for the hard 

 ice, which extended from the central peak to the sea. 



If we review the facts now presented, we have exhibited 

 the phenomena of fixed icebergs or glaciers, strewed with 

 stones transported from the mountains, and covered with a 

 new deposit of ice and snow : large blocks of stone, in the 

 perpendicular wall of the iceberg, overhanging the sea ; piles 

 of sand on the high glaciers ; sand and volcanic scoriae cov- 

 ering the low glaciers upon the borders of the sea ; and a 

 body preserved for years from decay in the solid ice, and 

 which might there remain thousands of years, like the elephant 

 of Siberia. We have only to conceive of the increase of 

 the low glaciers by the causes already indicated, and of the 

 advance of all the ice which contains these extraneous mate- 

 rials into the deep seas which wash the polar coasts, of por- 

 tions being detached, and floating into northern seas, to have 

 in action, in our own day, the power which is supposed to 

 have transported the materials of the drift from the ancient 

 mountain-sides. 



The supposition above made, that the glaciers, situated as 

 those above described, might, in time, reach the sea, and be 

 floated from the shore, will not appear improbable, when we 

 consider the manner in which the glaciers advance, and the 

 separation of the iceberg from the shore. Upon this difficult 

 subject, the researches of Charpentier, Agassiz, Forbes^ and 

 others, on the glaciers of the Alps, have thrown much light* 

 The glaciers of the Alps and Spitzbergen are filled with innu- 

 merable fissures, produced, as Agassiz conjectures, by the 

 expansion of compressed bubbles of air within the ice. These 

 fissures are generally parallel with tlie front face of the glacier ; 

 larger fissures or crevices are produced during summer. The 



