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CHAPTER I. 



THE GENESIS OF THE EARTH. 



The title of this work is intended to indicate precisely 

 its nature. It consists of rougli, broad sketches of 

 the aspects of successive stages in the earth's history, 

 as disclosed by geology, and as they present themselves 

 to observers at the present time. The last qualification 

 is absolutely necessary, when dealing with a science 

 whose goal to-day will be its starting point to-morrow, 

 and in whose view every geological picture must have 

 its light and shaded portions, its clear foreground and 

 its dim distance, varying according to the lights cast 

 on them by the progress of investigation, and accord- 

 mg to the standpoint of the observer. In such pic- 

 tures results only can be given, not the processes by 

 which they have been obtained ; and with all possible 

 gradations of light and distance, it may be that the 

 artist will bring into too distinct outline facts still only 

 dimly perceived, or will give too little prominence to 



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