82 GEOLOGY. 



where rock. However deep may be the cavities which 

 hold the water, there is a rocky bottom, and, dig wher- 

 ever you will, rock is found beneath the earth and sand. 

 It is said by Bakewell that " the crust of the globe with 

 which we are acquainted does not exceed, in comparative 

 thickness, that of a wafer to an artificial globe three feet 

 in diameter." 



159. Land and Water. The surface of the globe is 

 reckoned as containing about 211,000,000 square miles, 

 of which about 150,000,000 are covered with water, and 

 61,000,000 appear as land. The proportion of water-sur- 

 face to land-surface is nearly 8 to 3. 



160. Elevations and Depressions in the Earth's Sur- 

 face. The elevations in the forms of hills, table-lands, 

 and mountains vary exceedingly, the highest being 

 Mount Everest, in the Himalaya range, which is 29,000 

 feet, or five and a half miles high. The ocean varies 

 much in depth, sometimes probably reaching to 50,000 

 feet, though no satisfactory soundings have ever ascer- 

 tained such a depth. The average depth is somewhere 

 from 15,000 to 20,000 feet. Often about the continents 

 there is a fringe, as we may term it, of shallows. On the 

 coast of the United States, off the State of New Jersey, 

 there is such a fringe 80 miles in width, the depth at its 

 edge (where the ocean really begins) being only 600 feet, 

 while the depth across the ocean, in a line from New- 

 foundland to Ireland, has been found to be from 10,000 

 to 15,000 feet. Some extensive waters, also, between dif- 

 ferent bodies of land, can not be regarded as parts of the 

 ocean. In the waters separating Great Britain from Eu- 

 rope the depth is less than 600 feet, and in a large part 

 of the German Ocean it is only 93 feet. Similar facts 

 have been discovered in regard to the waters between 

 Asia and the islands appended to it. These should really 

 be considered as a part of the continent of Asia, and Great 

 Britain as a part of the continent of Europe. 



Although the projection of the earth at the equator is 



