58 R. M. Deeley — Climate and Time. 



earth be fixed and permanent, there must be never-ending fluctuations 

 in the mean temperature of every zone; and the climate of one area 

 can no more be a type of every other, than is one of our four seasons 

 of all the rest." 



Lyell goes on to describe the " position of land and sea which 

 might produce the most extreme of cold of which the earth's surface 

 is susceptible", and concludes that if the continents were grouped 

 about the equator the extreme of heat would be experienced, 

 whereas if they were grouped about the poles the extreme of cold 

 would be attained. 



There is nothing in Lyell' s writings to lead us to suppose that he 

 thought that the continents were ever grouped in this way. He 

 assumes such an arrangement as an extreme case to show that his 

 theory will hold even then ; and he clearly recognizes the fact that 

 even comparatively small changes in the distribution of the land 

 would considerably affect the climate. 



James Geikie, 1 discussing Ly ell's theory, says, "But we are 

 assured that no such distribution of land and water as Lyell thought 

 necessary for the production of our Glacial Period ever obtained in 

 Pleistocene times. We have no reason to doubt that the positions 

 of land and sea were practically the same as they are now." But 

 the view is now gaining ground that the changes in the distribution 

 of land and sea which are known to have occurred in Pleistocene 

 times were sufficient to affect the temperature appreciably. 



Croll 2 also dissented from Lyell's theory. He says, "The only 

 other theory on the subject worthy of notice is that of Sir Charles 

 Lyell. These extraordinary changes of climate are, according to his 

 theory, attributed to differences in the distribution of land and water 

 ... It will be shown in subsequent chapters that this theory does not 

 duly take into account the prodigious influence exerted on climate by 

 means of the heat conveyed from equatorial to temperate and polar 

 regions by means of ocean currents." Lyell did not go to the 

 lengths Croll did on this subject ; but that he was quite well aware 

 of it and considered it the following remarks of Lyell show : " The 

 general climate of Europe is materially affected by the volume of 

 warmer water thus borne northwards; for it maintains an open sea 

 free from ice in the meridian of East Greenland and Spitzbergen." 



Mr. C. E. P. Brooks 3 has recently devised an empirical method of 

 calculating the probable alteration in the temperature that might be 

 expected from known geographical changes in the outline of the 

 continent of Europe during late geological times, and he considers 

 that they were sufficiently great to cause the Glacial Period. 

 However, he recognizes that such changes could not account for the 

 four great cold periods of the Pleistocene we are now corning to 

 recognize. He suggests that the weight of the ice slowly weighed 

 down the land until the new geographical conditions thus introduced 

 caused the ice to disappear and the climate to ameliorate. On the 



1 The Great Ice Age, 3rd ed., p. 792. 

 3 Climate and Time, p. 8. 



3 Quart. Journ. Roy. Met. Soc, vol. xliii, pp. 159-73, and vol. xliv, 

 pp. 253-70. 



