192 A. P. COLEMAN DRY LAND IN GEOLOGY 



The same may be said of the deep-sea deposits on Timor, in the East 

 Indies, recently described by Molengraaff. 19 In position Timor is almost 

 the counterpart of the Barbados in the West Indies. 



The distribution of plants and animals should be arranged for by other 

 means than by the wholesale elevation of ocean beds to make dry-land 

 bridges for them. W. D. Matthew's excellent paper on climate and evolu- 

 tion suggests ways in which this may be done more economically. 



The elevation of mountain chains by folding or the overriding of 

 blocks might be expected to make trouble for the isostatic theory ; but the 

 two best known examples, the Eockies and the Himalayas, seem to be 

 approximately in isostatic equilibrium. In the case of the Himalayas, the 

 youngest and highest of the great mountain systems, it is staggering to 

 find nummulitic beds 20,000 feet above the sea; but, however it was man- 

 aged, enough light material seems to have been introduced beneath to 

 float the mountains at about the proper height. 



We may conclude that, broadly speaking, the dry-land areas have al- 

 ways been where they are now. The adjustments of the boundaries of 

 land and sea have been confined to the margins of the continental masses. 



Teleological Considerations 



There are certain teleological features of the relations of land and 

 water to which attention may be drawn in closing. Without water, no 

 life such as we know would be possible. On the other hand, uniformly 

 deep water over the whole earth, such as might have been expected in a 

 rigidly mechanical scheme, would probably not have provided the condi- 

 tions necessary for the development of life. An apparently accidental 

 lack of homogeneity in the earth allows lighter parts to rise above what 

 would otherwise have been a universal sea. The combined efforts of the 

 epigene forces since the earliest known times have been directed toward 

 the destruction of continents and islands and their reduction to shoals 

 completely covered by the sea, but their efforts have always been foiled by 

 movements originating in the earth's interior. No continent seems to 

 have been completely submerged since Triassic times. The life of land 

 plants and animals appears to have been uninterrupted since that time 

 on all the continents. 



There has been perpetual oscillation in respect to the area and eleva- 

 tion of land exposed, but on the whole the balance has been carefully 

 maintained. But for the presence of oceans of water, of an abnormal 

 lightness in some parts of the earth's crust, and an unfailing balance for 

 50,000,000 years between the forces of elevation and of destruction, life 

 such as ours would have been impossible. Can we look on these surpris- 

 ing adjustments as merely accidental? 



1S Koninklijke Akad. v. Wetenschappen, Amsterdam, deel xxiy, pp. 415-430. 



