IN THE DP:PTHS 



69 



There are other ways whereby land deposits 

 get into the sea beds — other ways than by wash- 

 ing down from the shores. From the poles, 

 reaching toward the temperate zones, there arc 

 vast plains or " banks," composed of fine detri- 

 tus which was originally carried seaward by 

 glaciers and icebergs; and, as the bergs melted, 

 gradually sank through the water to the bot- 

 tom, forming there a glacial ooze. Again the 

 basin of the Mediterranean, along the African 

 coast, has been changed in no small degree by 

 the sands of Sahara caught up in the air by 

 southern siroccos and scattered far and wide 

 upon the waters. And, again, there is no doubt 

 that such volcanic eruptions as the recent one 

 upon the island of Martinique, with its clouds 

 of dust and ashes, have a decided effect upon 

 the adjacent sea floors. 



But the deep-sea beds, containing what arc 

 called the " abysmal deposits," are not influ- 

 enced by shore or land changes. In five hun- 

 dred fathoms of water, and far removed from 

 land, ninety per cent of the sea floor may be 

 made up of the empty shells of foraminifera, 

 pteropods, and other organisms that live in and 

 upon the surface of the water. After the death 

 of the occupants these infinitesimal shells sink 

 slowly through the dark waters to the ocean's 



Glacial 

 ooze. 



Volcanic 

 dust. 



Abyswil 

 deposits. 



