306 GEOLOGY. 



go back in the comparison the more striking does it ap- 

 pear. To say nothing of that period or age when the 

 earth was in a fused condition, look at the Azoic age 

 as compared with the present. When the extent of 

 land was small, and there was no life either on land, or 

 in water, or air, there were no high mountains, and no 

 rivers of any size. It was a dull, monotonous world, 

 compared with the variegated earth which we have now, 

 with its continents, islands, mountains, lakes, and rivers, 

 all swarming with busy and noisy life. A strong con- 

 trast can be made out in regard to the ages that follow- 

 ed, especially in relation to the changes of various kinds 

 that were necessary in making the requisite additions to 

 the continents, such as flexures, upheavals, denudations, 

 deposits, elevations, subsidences, etc. Disturbances, it is 

 true, are occurring in this age, many of them precisely of 

 the same character ; but they are not so great, nor so 

 wide in their range. For example, glaciers and icebergs 

 are at work now ; but their work is not continent-wide, 

 as it was in the Glacial age, when ice reigned supreme 

 over a large portion of the earth, in order to prepare it, 

 as you have seen, for man. So, in the formation of peat, 

 we have the same thing essentially as was the grand 

 business of the Carboniferous age ; but it is a small op- 

 eration compared with the coal-making of that period. 

 The Post-tertiary period was the nearest in character to 

 the present, especially the Terrace epoch, for the conti- 

 nents were then finished, and all the grand general work 

 of diversification of the surface was completed, only the 

 minor diversification, as it may be termed, remaining to 

 be done. 



416. Completion of the Earth. Although changes, and 

 those of no small extent, are now going on in the crust 

 of the earth, yet, in a certain sense, it may be regarded 

 as having been completed at the time when man was in- 

 troduced upon it. This conclusion is seen to be true if 

 we consider certain prominent facts, viz., that the conti- 



