CLIMATE OF PLEISTOCENE PERIOD. 55 



feet in thickness, and contains oak in its upper part, with pine 

 lower down. Between the peat and the clay upon which it 

 rests occur leaves of Betula alba and pine cones, and in the 

 uppermost layers of the clay leaves of Myriophyllum, Dryas 

 octopetala, dwarf birch (Betula nana), and Salices appear, along 

 with wing-cases of beetles. A little lower down in the clay are 

 found leaves of the netted-leaved willow (Salix reticulata) and 

 Arctic willow (Salix polaris), the latter being a characteristic 

 Spitzbergen plant. Certain peat-bogs of Bavaria have yielded 

 similar evidence of colder climatic conditions, and we are sup- 

 plied with still more remarkable testimony to the same effect 

 by the well-known tufa and peat of Schussenried in Swabia. 1 

 This peat contains northern and high-alpine species of mosses, 

 such as Hypnum sarmentosum, which ranges north to Lapland 

 and Greenland ; H. aduncum and H, fluitans var. tenuissimum, 

 which is a high -alpine and Arctic American form. Such a 

 flora is quite in keeping with the character of the shells and the 

 mammalian remains which occur in the tufa commingled with 

 relics of Palaeolithic man. The shells are well-known "loss" 

 forms, of which I shall speak later on, while the mammalian 

 remains belong to reindeer, glutton, Arctic fox, etc. 



Mr. Nathorst, 2 a well-known Swedish geologist, has followed 

 the spoor of the old arctic flora from Southern Sweden into 

 Denmark and England, and through Germany to Switzerland. 

 In Mecklenburg, as in Switzerland and Bavaria, he has detected 

 in certain freshwater clay -deposits leaves of the dwarf birch 

 (Betula nana), and the white or common birch (B. alba), 

 associated with shells of northern forms. But the peat-bogs of 

 Northern Europe belong to a somewhat later date than those 

 lignites and turbaries of the central and southern regions to 

 which I have specially referred, and they need not therefore be 

 considered at present. 



The tufas of the south of Europe, as already described, give 



1 0. F. Fraas, Wurttcmb. Jahreshcfte, Bel. xxiii. (1867), p. 48 ; Arehiv fur 

 Anthropologic, Bd. ii. (1867) ; Compt. Rend, du Congres d'Anthrop., 1869, p. 286. 



2 Ofversigt af K. Vet.-Akad. Fork., 1873, No. 6, p. 11 et seq. 



