120 THE CULTURE OF FARM CROPS. 



incomprehensible to our minds in its intensity, and of which 

 we have an example in the present condition of the sun. 

 In course of ages the gases became condensed to fluids and 

 by a gradual process of cooling the various elements became 

 plastic and more adherent ; separating from each other by 

 molecular attraction and forming layers or masses, which 

 formed a crust around the central portion, still fluid from 

 the retained heat. 



At this period of the earth's history it was surrounded by 

 a dense atmosphere of steam ; produced by the vaporization 

 of the water by the heat. Upon still further gradual cool- 

 ing the watery vapor became condensed, in part ; and the 

 heated masses of plastic rock were enveloped in an ocean of 

 boiling water, above which floated the dense volumes of 

 steam. Here was indeed chaos, and the darkness which 

 covered the waters and the earth. As the cooled crust 

 hardened, it shrank, and as the pressure of the molten mass 

 within it burst the thin shell, it was vomited forth into the 

 ocean, causing explosions and outbursts of steam, which as- 

 cending, became cooled and fell in tremendous torrents of 

 rain, into the ocean. A seething, boiling, tumultuous ocean, 

 thus enveloped the globe; while vast eruptions from 

 beneath it forced mountain masses of plastic rock far above 

 its surface, and these were washed with the descending rain 

 torrents. The soft rock was thus broken down into mud 

 which flowed into the depressions, forming vast beds at first 

 horizontally spread out. All this went on during vast ages ; 

 a period of terrible commotion and chaotic disturbance. 

 As the gradual cooling proceeded, the disturbances became 

 less frequent. At times the pressure from below the hard- 

 ened crust lifted this slowly, breaking it into fissures and 

 throwing up the rocks upon their edges, or into vast waves. 

 These waves of rock were sometimes burst at their summit, 

 when melted matter flowed over them and filled the depres- 

 sions between them ; or one side of the broken crust would 

 fall back to a lower level leaving a precipitous wall of rock 

 on the other side. The ocean beating upon these heated 

 rocks, quickly wore them down into mud or sand; and 



