468 ME. r. W. HARMER ON THE [^"g* ^QOIj 



perhaps by meteorological changes arising, directly or indirectly, 

 from tectonic disturbances in Europe or America/ or possibly in 

 Asia, to have regained its ascendancy, restoring the earlier state of 

 things, though not perhaps to so great an extent as at first. 

 Secular changes in climate arising from causes like these may thus 

 have taken place during the Glacial and i post-Glacial Periods, 

 gradually diminishing in intensity, nntil the exciting cause of the 

 increased cold, whatever it may have been, had finally passed away. 



Glacial conditions seem to have existed during one stage or an- 

 other of the Pleistocene Epoch in the Southern Hemisphere, as in 

 Australia, New Zealand, and South America, due, it is supposed by 

 some authorities, to changes in the relative levels of land and sea. 

 Such changes must necessarily have been attended by disturbances 

 of the baric equilibrium, and in the direction of the prevalent 

 winds, and the influence of the former may have been felt even in 

 the JSTorthern Hemisphere. - 



When we consider the complicated character of the laws affecting 

 the atmospheric circulation, it is not difficult to understand that in 

 this way, or in others which it is not necessary to indicate, meteoro- 

 logical disturbances may have been set up, the influence and extent 

 of which it is impossible to determine. 



The hypothetical charts illustrating this paper are intended to 

 represent the conditions which may have obtained at two stages 

 only of the Pleistocene Epoch — namely^, those of the maximum ex- 

 tension of the ice in North America, and in Europe, respectively. 

 Almost any number of other meteorological combinations may, there- 

 fore, have existed from time to time during that era. It all the 

 facts were before us, the geology and the meteorology of the Glacial 

 Period would necessarily prove to be in exact accordance. At present 

 our information is but scant}', and the palaeometeorologist must 

 work with the best material that he can obtain, content with 

 the enunciation of general principles, and with the solution of some 

 of the more simple problems presented to hira. 



In deprecation of the criticism that this paper is of a highly 

 speculative character, I may perhaps urge that it is not the first of 

 its kind on the climate-question. The length which it has attained, 

 much greater than I originally intended, must serve as my excuse 

 that I have been able to treat this many-sided subject, which is 

 clearly of great difficulty, from one standpoint merely, and, I 

 fear, in a somewhat superficial manner. The views here stated 

 are offered in a suggestive, and not in a dogmatic, spirit, and the 



^ Prof. J. W. Spencer believes that movements of subsidence and elevation 

 took place mere than once in the Antillean region daring the post-Pliocene 

 Epoch. 



^ The opinion has been expressed that some of the climatic changes of the 

 Glacial Period were more or less sudden ; see, for example, Warren Upham, 

 Journ. Vict. Inst. vol. xxix (1897) p. 201. Changes in the weather are pro- 

 verbially so; the latter arise, as 1 suggest the former may have done, from 

 variations in the direction of the winds. 



