22 LAND AND WATER. 



tain copper, iron, and other valuable substances, 

 mixed with earthy matter. In many places, coal, 

 salt, and various other productions of great value, 

 are found deep in the bowels of the earth. The large 

 and deep openings made to obtain them are called 

 mines, and the earthy or stony matter, among which 

 the metals and minerals are found, are called ores. 

 Men employed in digging mines are called miners. 



Mountains which send forth flames and clouds 

 of smoke are called volcanoes. These sometimes 

 discharge also streams of liquid matter called lava, 

 which look like rivers of fire, and spread terror, 

 death, and destruction around. The principal vol- 

 canoes in Europe are Vesuvius and ^Etna. 



Fire and water have formed in the earth many 

 extraordinary caverns, some of which run for miles 

 under ground, and terminate in abrupt precipices. 

 The water incessantly dropping from the roofs of 

 caverns, sometimes forms what are called stalac- 

 tites, which hang down in a variety of curious and 

 beautiful shapes. 



In some parts of the earth mighty torrents have 

 broken through and rent asunder huge mountains, 

 the sides of which now form, as it were, immense 

 gateways. Such was the origin of the straits by 

 which some countries are separated, and seas have 

 become connected : the straits of Gibraltar supply 

 an instance, where Europe and Africa approach 

 near to each other, and by which the Mediterra- 

 nean sea is connected with the Atlantic ocean. 



