GEOLOGY. 125 



being also produced ; the mountain chains therefore 

 upon the earth agree in the main with the water courses, 

 and, though not generated from, have been certainly 

 changed in character by, the latter. Such must be our 

 conclusion, if in the formation of the earth nothing 

 but crystallization be taken into consideration. Con- 

 densation alone brings yet other phenomena along 

 with it. 



566. The first and most important of these is the 

 elevation of temperature. We cannot think otherwise 

 than at the first precipitation of the earthy a number of 

 huge cavities remained in the interior of the earth, which 

 were filled with water. This being heated, was converted 

 into steam, which thrust up the superincumbent rock, 

 and converted it into new mountains or mountain-chains. 

 These agencies of heat may be called primary volcanoes, 

 although they are not to be confounded with volcanoes 

 proper. 



567. The igneous cavities were probably placed in a 

 certain order, according with the original edges and 

 angles of the earth's body. They may have therefore 

 thrown up mountain tops and chains. 



568. But the cavities, besides raising mountain chains, 

 could just as well depress or allow them to sink in, and 

 thus produce valleys. By these means the seas have 

 probably been formed. Like the seas so also have the 

 inland seas or lakes originated. 



569. Lastly, a similar origin must be ascribed to the 

 world-sea or ocean. Many earthquakes arose, with all 

 their concomitant phenomena, by partial and sudden 

 falling in of the deep descending cavities of the earth. 

 Frequently that which fell in was again driven out by 

 the expansive force of the suddenly compressed air. 



2. Organs of the Planet. 



570. The principal mass or body of the planet is 

 formed by the earths proper, as being the typical or 

 genuine representatives of the earth-element. The other 



