3 io SCIENCE PROGRESS 



In the examination of the peat samples brought back to the 

 laboratory, much help has been obtained by the use of the method 

 described by Gunnar Andersson (2). Samples of the peat are 

 treated with nitric acid, which completely deoxidises the 

 material, loosens, and at the same time bleaches it. The peat 

 is then placed in sieves and the loose debris washed away, 

 leaving any seeds and fruits which it may contain. Fragile 

 leaves are usually broken into fragments during this process, 

 and they can best be obtained by dissecting them out from the 

 peat without previous treatment. 



In the south of Scotland two forest beds invariably make 

 their appearance — a lower of birch {Betula alba) and an upper 

 of pine {Pimis sylvestris). The Lower Forest rests directly upon 

 glacial deposits and contains an assemblage of plants indicating 

 climatic conditions not unlike those of the present day. This is 

 overlaid by 3 or 4 ft. formed almost entirely from the remains 

 of Sphagnum and Eriophoriun vaginatum. Above this, the plant 

 remains indicate an entirely different set of conditions, for peat bog 

 plants are replaced by an assemblage of well-marked arctic 

 plants, such as Loiseleuria procumbcus, Salix reticulata, S herbacea, 

 together with Empetrum nigrum. Salix reticulata now grows 

 only on the summits of the higher Scottish mountains, generally 

 above 3,000 ft., and its presence between two forest beds in the 

 south of Scotland indicates a period when the valleys in the south 

 of Scotland had a climate at least as rigorous as that at present 

 obtaining on the summits of the highest Scottish mountains. 

 If climatic conditions were such over the south of Scotland, 

 it is extremely probable that glaciers would exist at the same 

 time amongst mountainous ground in the Highlands. 



The gradual dying away of this cold period and the incoming 

 of a forest vegetation is faithfully reproduced in the peat. Arctic 

 willows and creeping azalea give place above to beds of 

 Eriophorum and Sphagnum. Later, the wet moorland conditions 

 indicated by these plants yield to pine forest in most districts of 

 the south of Scotland. This forest period at length came to an 

 end and was succeeded by wet conditions, as the peat immediately 

 above the forest zone is formed entirely from Scirpus, Sphagnum, 

 and Eriophorum. 



The Highland areas reproduce the later stages found in 

 the Southern Upland peat, but the earlier stages are wanting. 

 The basal layers contain the remains of an arctic flora similar to 



