94 THE WATERS. 



the term " ocean " being applied to the larger tracts of water, 

 as the Atlantic Ocean, the Pacific Ocean, &c. All the great 

 oceans and seas unite, and, in reality, form one great world 

 of waters, spread out and covering all the lower parts of 

 the earth, the term "lake" being applied to collections of 

 water surrounded by land, although the Caspian Sea retains 

 the name of sea, and some of the great lakes of America 

 may well deserve such a name. 



The waters of the sea fill up all the lower parts of the 

 earth, so that, almost without exception, the land is higher 

 than the water, and as the land in some places rises but a 

 few feet, and in others as many thousands, so, beneath the 

 sea, the land sinks in many places but a few feet, and 

 in others perhaps as many thousands as it is known to 

 rise above it. The sea always maintains the same general 

 level, although in past ages the land has risen and fallen, 

 sometimes in one place and sometimes in another ; indeed, 

 the same process is taking place every day, but in so 

 slow a manner that centuries are required to make any 

 great alteration ; while some tracts of land are being en- 

 croached on by the action of the waves, others are being 

 added to and elevated by accumulations of mud and sand, 

 or raised by the action of earthquakes and volcanoes, which 

 throw up under the sea, as well as on the land, vast 

 quantities of melted earth or lava, forming strata known to 

 geologists as basalt, tufa, &c., or eject showers of ashes and 

 dust in such prodigious quantities as to cover many hundred 

 square miles of the earth's surface. It was by one of 

 these showers of ashes from Vesuvius that the cities of 

 Herculaneum and Pompeii were buried. So that, as a whole, 

 although the sea is continually altering slowly its position, 

 yet it pretty equally maintains the same elevation. At first 

 thought it may be supposed that the rivers constantly 

 flowing into the sea would alter its level, for some are so 

 large that millions of tons of water are brought by them 

 into the sea every hour, and there are thousands of rivers 

 and rills which, night and day, pour in their tribute of 

 waters ; but G-od has wisely and kindly arranged these things 

 (like all others) so that they shall afford us innumerable 



