SOLUTION OF THE CLIMATE PROBLEM RAMSAY 245 



the polar regions, where the heated sea remains unfrozen and the 

 climate becomes genial. If we further consider the regular circula- 

 tion of the winds, disturbed by no mountains or elevations, and the 

 augmented selective absorption of the atmosphere, we shall under- 

 stand the conditions which led to the pliothermic climates, of which 

 the fossils and sediments give evidence. 



We need not look for any other cause of the great changes of 

 climate during past periods or of the ice ages, than the changes of 

 relief which the continents have undergone. 



II 



It is also generally admitted that a mountainous relief is an essen- 

 tial condition of glaciation. But against the assumption that oro- 

 cratic relief is the cause of ice ages, it has been argued that the relief 

 has not shifted during the Quaternary period in a manner corre- 

 sponding to the great differences in the climate of the ice age and 

 recent times and of the repeated glacial ages and interglacial ages. 

 And consequently, as change of relief can not be the cause of the 

 Quaternary alternations of climate, the actual cause of them, when 

 once found, may also prove to include a better explanation of the 

 greater climatic changes than the relief hypothesis. This objection 

 does not destroy the theory. 



For, if a miothermic climate is established — owing to an orocratic 

 relief, as I think, or to other causes — it will for a long time oscillate 

 between severer and milder conditions before a certain equilibrium 

 is reached. Paschinger * has recently tried to show that the influence 

 exercised by glaciation itself upon the level of " the zone of maximal 

 precipitation " and on its own growth and decay, brings with it cyclic 

 variations great enough to lead to glacial and interglacial stages. 

 Certainly those meteorologic factors help to enhance and diminish 

 glaciation, but it seems that the repeated accumulation and dissolu- 

 tion of the ice caps is due to alternating elevations and depressions 

 of the glaciated regions. 



This was suggested by Upham,^ referring to Jamieson's ^° assump- 

 tions that the regions had sunk under the load of the ice caps and 

 been raised by the removal of this load. Meanwhile, he combined 

 with his theory features from the astronomic explanations of the 



* V. Paschinger, " Die Eiszeit ein meteorologischer Zyklus " : Zeitschrift fur Gletsclier- 

 kunde, xiii, Leipzig, 1923, pp. 29-65. 



» Warren Upharn, " Probable Causes of Glaciation." In G. F. Wright, " The Ice Age in 

 North America," London, 1890, Appendix, pp. 573-593. " Pleistocene Climatic Changes " : 

 Geol. Mag., 1894, pp. 340-349. 



"> T. F. Jamieson, *' On the History of Last Geological Changes in Scotland " : Quart. 

 Journ. Geol. Soc, xxi, London, 1865. " On the Causes of Depression and Reelevatioa 

 of Land during the Glacial Period " : Geol. Mag., 1882, pp. 400-407 and 457-466. " On 

 Some Changes of Level during the Glacial Period and Their Causes " : Geol. Mag., 1887, 

 pp. 344-349. 



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