DIASTROPHISM AND THE FORMATIVE PROCESSES 135 



which Hfe of sub-tropical aspect flourished in the surface seas of 

 polar latitudes, it is not apparent how ice-cold waters could fill 

 the abysmal depths in low latitudes as they do now; nor can similar 

 salinities or gas-contents be safely assumed. The gas-content of 

 the deep-sea waters at present seems clearly to be the result of high 

 absorption in the cold polar regions where the absorption of oxygen 

 is about doubled for a lowering of temperature of 30° C. and the 

 absorption of carbon dioxide doubled for a lowering of about 20° C . 

 I have elsewhere urged that there was a reversal of present deep-sea 

 temperatures at the times when the remarkable stages of polar 

 warmth prevailed, and that the reversal was the cause of such 

 warmth.^ If such reversal took place, it would probably modify 

 rather radically the gas-content, as, by hypothesis, it did the 

 salinity and temperature of the deep-sea waters, and hence, no 

 doubt, their life. Whether this view be accepted or not, the diffi- 

 culty of rationally postulating the persistence of ice-cold abysmal 

 water in a stratum lying between the heated interior of the earth 

 and a surface stratum sufficiently warm to sustain reef-growing 

 corals in high latitudes is manifest. It is a much safer assumption 

 that the temperature of the abysmal waters is variable, and has 

 usually followed the climatic episodes that have dominated the 

 earth's temperature in general. 



It is almost certain that oceanic life is more responsive to such 

 changes of temperature as occur in nature than to such changes 

 of pressure as it usually encounters. Life is indeed seriously 

 affected by changes of pressure that are so rapidly forced upon it 

 as to prevent a distribution of the pressure increment or decrement 

 throughout the tissues, but organisms do not often suffer such 

 sudden changes in the course of nature. A change sufficiently 

 slow to permit a gradual equalization of pressure seems to be toler- 

 ated by sea life with relative indifference. According to Murray 

 and others some species of rather free-moving forms have a bathy- 

 metric range of 3,000 meters and more. Some species indeed seem 

 to pass from one pressure to another in short periods without ill 

 effects. The present adaptations of abysmal life may therefore be 



' T. C. Chamberlin, ^On a Possible Reversal of Deep-Sea Circulation and Its 

 Influence on Geologic Climates," Proceedings of the Anier. Phil. Soc. (1906), Vol. XLV. 



