THE PREPARATION OP THE EARTH FOR MAN's ABODE, 95 



the sedimentary rocks before that containing inidoubted 

 evidences of the advent of man, Ave read the records of the 

 consummation of the preparation of an abode for man. 

 Physical changes will of course continue, but we have no 

 reason to suppose that new forms of life will appear. 



The most striking features of the work of Tertiary times 

 are (1) the production in tlie rough, if I may so say, of those 

 great modellings and sculpturings of the land that now 

 diversify its surface, and (2) the great development of the 

 highest organic forms, both animal and vegetable. 



The elevation of great mountain ranges, mountainous 

 regions, and plateaux, though not of all, the cutting of river- 

 valleys, the spreading out of great low plains, the formation 

 of lakes, the separation of islands from the large land masses, 

 and the production of coast lines, as we now know these 

 geographical features, were in the main the work of the 

 Tertiary epoch. Some, it is true, of the great surface 

 features of the earth have a much older date, and, on the 

 other hand, considerable modification of the featru'es of 

 Tertiary geography has been accomplished by the un- 

 ceasingly acting agencies of nature, operating geologically 

 all through tlie by no means short Quaternary epoch quite 

 Tip to the present, time. But it is still true that the present 

 physical features of the land were, in the main, the work of 

 Tertiary times. 



Miocene rocks occur at an elevation of 5,000 feet in the Alps, 

 and Pliocene strata are found as high as 14,000 feet in the 

 Himalayas. To elevation during the Tertiary epoch is due the 

 ■chief part of the height of the Andes in South America; and 

 the Rocky Mountains in North America, in which Cretaceous 

 strata are now 14,000 feet above the level of the sea, may 

 also be termed Tertiary mountains, although part of the 

 elevation has taken place in both older and newer 

 ■epochs. 



In the British Islands the Avork of geological agencies in 

 the Tertiary epoch has left very conspicuous results. In the 

 Isle of Wight Cretaceous and Lower Tertiary strata are now 

 so far altered from their original horizontal position as to be 

 •absolutely vertical. The denudation of the chalk has been 

 :so great that although from its protective covering of basalt 

 the chalk has been preserved in the North of Ireland, all the 

 pai't that once was continuous to the chalk of Sussex has 

 been swept aAvay except that to the south-east of a line from 

 Dorset to Flamborough Head, and in this area the greater 



