472 Transactions. — Geology. 



The same applies in the case of air, strong winds being the 

 result of wide contrasts of temperature combined with the 

 tendency which is found everywhere to make everything of 

 the same mean or average heat. In the earlier periods of the 

 earth there was a greater closeness of temperature in the 

 waters of the ocean than there now is, just as there was in 

 the temperature of the air. There could be no sea or ocean 

 until the temperature had fallen below that of boiling water, 

 and when condensation began the water contrasts were small, 

 and whatever animal and vegetable life existed was limited by 

 the closeness of its contrasts. This was at the beginning of 

 life in this earth of ours. Since then contrasts have increased 

 as each new geological period has come into existence. Loss 

 of heat in the earth,- followed by contraction, has brought 

 about increasing contrasts, and these have been followed by 

 the rapid multiplication of differentiation adapted to the new 

 conditions. Now, are we to suppose that this condition of 

 things has not been continuous, and that climatic changes, 

 with their attendant modifications of animal and vegetable 

 life, had reached their maximum of differentiation, to be 

 followed by a throw-back period, which accords with the 

 sequence in the order of animal and plant life such as 

 existed at the time when the Glacial period is said to have 

 begun ? 



This Glacial period has been generally recognized by all the 

 geologists of Europe and America, and the facts are such that 

 it is evident glaciers or aqueous movements must have existed 

 to a far greater extent than they do to-day over certain areas 

 of the earth's surface. But, whilst granting this, is it necessary 

 that causes should be sought for outside the ordinary physical 

 phenomena which regulate the surface-changes such as are 

 now going on? .Is it possible to suppose that at some period 

 of the earth's history a fresh-water lake could be sustained 

 from the surplus drainage of an area equal in extent to that 

 which is said to have been glaciated? For, if so, there appears to 

 be no greater difficulty in supposing that with a slightly higher 

 elevation the same amount of condensation could take place, 

 and under special physical conditions like those now existing 

 for the production of the Tasman and Franz-Josef Glaciers in 

 New Zealand a so-called glaciated area could be produced 

 equal in extent to what is said once to have existed in Europe 

 or America. Let the fact be remembered that a Glacier is 

 a secondary product, representing the surplus condensation 

 beyond the snow-limit. As soon as the neve or Jim exists 

 there is a tendency in the plastic mass to move ; but the 

 movement is only possible below the snow-line so long as the 

 supply is in excess of the melting-capacity of the sun's rays 

 acting on the mass. The glaciated area of Europe represents 



