148 



The Glacial Theory, 



when such accumulations are the combined effect of the two causes, 

 as may have been the case on maritime shores, where the glaciers of 

 neighbouring mountains terminated at the coast. It must likewise 

 not be forgotten, that sometimes small lakes are formed on the flanks 

 of glaciers, in which the matters triturated by the glacier are depo- 

 sited in regular beds, without being carried very far. It is of con- 

 sequence to keep all these facts in view, when we study the forma- 

 tion which geologists have termed diluvium, and whose various 

 phenomena have hitherto been erroneously attributed to one single 

 cause, — currents. 



It appears to me probable, according to the facts which I have 

 been able to combine in considering this question, that the organized 

 beings of our epoch were created successively, after the commence- 

 ment of the retreat of the ice. Wherever the surface of the ground 

 made its appearance between the glaciers, under the influence of a 

 milder climate, — wherever, yielding to the temperature, the ice pro- 

 duced pools of water, — the development of organized beings might 

 take place ; and direct observation has already confirmed what the 

 theory required. Mr. Smith of Jordanhill was the first to point out 

 in the post-tertiary clays, which are superior to the till (that is to 

 say, which have been deposited posteriorly to the accumulation of 

 those masses of gravel and rolled blocks in the mud under the anci- 

 ent glaciers), numerous fossils of species that no longer exist simi- 

 larly associated on the neighbouring coasts ; he has even ascertained 

 the identity of some of those shells with species which have hitherto 

 been observed only in the Arctic seas. A fact so unexpected did 

 not fail to excite my curiosity in a high degree, and I have ever 

 since been unremitting in my endeavours to compare these fossils 

 with living species. Assisted by a collection of living species from 

 Greenland, which I owe to my friend Professor Eschricht of Copen- 

 hagen, I have not only confirmed the first impressions of Mr. Smith, 

 but have further found among the fossils of these clays a much 

 larger proportion of Arctic species than could have been expected. 

 Extending this species of research to the most recent fossiliferous 

 deposits of other parts of Europe, I have every where met with a 

 certain proportion of species whose types no longer exist in a living 

 state in the neighbouring seas, but at 12° or 15° of latitude more to 



