142 SEA AND LAND 



great distance from tlu-ir birthplace. If the berg remains for 

 a long time in the position in wliich it entered the sea, a rela- 

 tively slight amount of melting will release the stones and 

 earthy waste, which will then fall, bit by bit, into the sea-floors 

 in the paths of the wandering ice ; but as it often happens 

 that the berg is turned upside down before it has attained any 

 great distance from its point of origin, in this position the 

 waste from the land will remain afloat until the ice again 

 capsizes or melts away, when it will be- tumbled into a heap on 

 the ocean bottom. In this way a very large amount of the 

 land waste torn from the bed rocks by the action of the 

 o-laciers is distributed far and wide over the surface, where 

 new strata are constantly accumulating. The number of ice- 

 bercrs delivered to the open sea in the summer season, of 

 either Pole, must amount to many thousands. It wmII be prob- 

 ably safe to estimate the aggregate area of this floating glacial 

 material as not less than five hundred square miles in surface. 

 It will also be reasonable to reckon that the debris from the 

 circumpolar lands contained in tliese bergs is sufficient to form 

 a layer not less than one foot in thickness over all this field of 

 ice. On this basis we find that in one thousand years the 

 sea-floor, over an area of one million square miles, might 

 receive a contribution of debris having a mean depth of six 

 inches. Although these reckonings are to be taken only as 

 probable, or perhaps possible, estimates, it is evident from 

 them that the land areas about the Poles are rapidly wearing 

 away, and that their waste is being deposited with extreme 

 rapidit\- ui)on the lloors of the oceans in hii^h latitudes. 



While th(; massive icebergs are carrying on this singular 

 work of depositing the waste of the circumpolar regions on 

 the wide fields of the oceans, the ice-floes are doing a similar, 



