202 The Scottish Naturalist. 



If the views he has advanced with regard to the origin of secular 

 changes of climate be well founded, we might have expected that 

 the alternation of cold and warm epochs which prevailed during 

 the pleistocene or glacial period could hardly have ceased with 

 such an extreme glacial phase as that which characterised the 

 last cold epoch of the Ice Age proper. We might have antici- 

 pated that proofs should be forthcoming of similar although 

 minor alternations of genial and cold conditions having obtained 

 in what is called the post-glacial period. As the eccentricity of 

 the earth's orbit decreased, the alternation of climate resulting 

 from the precession of the equinox would gradually become less 

 marked, and to some extent would be modified by changes 

 in the distribution of land and sea. It is to such minor muta- 

 tions of climate that our post-glacial accumulations bear witness. 

 I would also point out that the views advanced in the present 

 paper afford a reasonable explanation of certain well-known facts 

 which have hitherto appeared somewhat enigmatical. They 

 account for the southern element in the fauna of our northern 

 seas, as well as for the presence of trees in the peat of arctic 

 lands; and they also give a good reason for the disappearance of 

 arboreal vegetation from arctic regions, and for the diminished 

 numbers of southern marine forms in the adjacent seas as con- 

 trasted with their greater abundance in certain post-glacial 

 deposits. Again, they sufficiently account for the extreme 

 freshness of the glacial a.ppearances in many of our mountain- 

 valleys, which, as we have seen, contained local glaciers at so 

 recent a period as late post-glacial and Neolithic times. 



The following short tabular abstract brings into one view what 

 appear to have been the leading features of glacial and post- 

 glacial times : — 



The Glacial Period.— Gr3at succession of alternate cold (glacial) 

 and warm (inter-glacial) epochs. During glacial epochs vici's de 

 glace cover wide areas in northern and north-western Europe, 

 enveloping British area, filling up adjoining seas, and extending 

 from Scandinavia down into the plains of Germany, as Dr Torell 

 was the first to point out. At same time, all the mountain-districts 

 of middle and even southern Europe support considerable snow- 

 fields and glaciers. Great migrations of fauna and flora in a 

 southerly direction. During inter-glacial periods migration takes 

 place in opposite directions ; and when climate is most genial, 

 African mammals, such as Hippopotamus, Elephant, and Hyaena 

 occupy England. Palaeolithic man also lived in IJritain. When 

 cold of last glacial epoch became most intense, Paleolithic man 



