10 The Phosphates of America. 



that when our globe was launched into space it was a liquid some- 

 what similar to molten glass, and therefore presented a vastly dif- 

 ferent appearance to that with which we are acquainted. When this 

 mass began to cool, it probably resembled an immense glass ball, 

 the solidified sides of which were uplifted by the bubbling of the 

 intensely hot liquid mass within. These solid projections formed 

 our mountains, and, passing from the transparent to the opaque, 

 they gradually assumed the crystalline form. What is known as 

 the earth's crust must have resulted from an extraordinarily for- 

 cible action consequent upon the fall of temperature. Certain 

 vapors were condensed into acid bodies, and these acids, attacking 

 the alkaline crust, combined with its most powerful bases to form 

 various salts. Some of these salts such as sulphate of lime or 

 gypsum were deposited, while others, principally the chlorides, 

 remained in solution and formed the seas. The neutralization of 

 the stronger and more corrosive acids permitted the weaker car- 

 bonic acid to develop its activity, and it is this acid which has con- 

 tinued to play the most important part in nature in our own times. 

 Held in solution by the running waters, it attacked and dissolved 

 the various bases which existed in such large quantities in the moun- 

 tains, and deposited them in the form of carbonates in the valleys. 

 The process of saturation, or neutralization, being entirely accom- 

 plished, chemical equilibrium may be said to have become estab- 

 lished ; the period of great geological catastrophes, therefore, came 

 to an end, and the temperature of the earth gradually sank below 

 the boiling-point. A few volcanic disturbances continued, it is 

 true, to occasionally convulse it ; there was the upheaval, splitting 

 asunder and complete overthrow of mountains, the drying up and 

 the division of seas, and the formation of lakes of both fresh and 

 salt water, but they became more and more rare as the temperature 

 continued to cool. 



The rocks with which we are all acquainted and which have 

 grown out of these continuous and still-continuing changes may be 

 roughly divided into three groups : 



First, SANDSTONES. 

 Second, LIMESTONES. 

 Third, GRANITE or GNEISS. 



And it is their decomposition, under the combined influence 

 of the atmosphere and water, during a long period, that has ulti- 

 mately produced fertile soils containing silicates of aluminum, 



