468 MR. G. ERDTMAN : STUDIES IN THE 
showing that there is a break of continuity between the glacial deposits and 
the peat that rests upon them.” There is nothing in the diagrams from 
Skye to contradict this supposition. Further down on the same page Lewis 
continues : The character of the basal layers of peat would seem to 
indicate more genial and drier conditions than obtain at present ; for the 
greater part of Skye and North Uist (about 75 per cent. in one and 90 per 
cent. in the other) now covered with peat was clothed with thick woods 
of birch and hazel, with some alder. Such a type of vegetation is hardly 
represented in the islands at the present day. Allowance must, however, 
be made for the fact that when this woodland period existed the peat was 
extremely thin and presumably better drained than now." 
As Alnus pollen does not occur in the oldest layers, the alder wood, which 
is sometimes found there, is presumably the remains of the roots of trees, 
which at a later time grew on the bogey ground. There seems no reason to 
suppose as Lewis suggests (l e. p. 340) that there would be a break in 
continuity between the upper and lower part of the wood-bearing stratum in 
the lower part of the peat mosses. Lewis describes abundance of Corylus 
Avellana (wood, bark, nuts) from Skye, and it is extremely interesting that 
pollen researches in Bohemia (Rudolf and Firbas, 1923), Scotland, and 
Sweden (von Post, 1920), show a maximum frequency of hazel-pollen in 
relatively early postglacial beds. In Skye, however, the hazel copses of this 
period seem to have had a rather local distribution. Sample 6 in No. 7 
(with 58 per cent. Corylus pollen) shows the greatest pine-pollen frequency 
in this moss, and may perhaps be synchronous with the A-zone. The same 
may be said of sample 5, No. à. 
C. Peat Mosses on the Island of Lewis. 
(Map used: Bartholomew's “ Half-inch to mile " map of Scotland, Sheet 23.) 
According to Lewis (ITI. 1907, pp. 47-48) the Lower Forest in this island 
usually consists of a thiek bed of birch, fairly large trees, mixed, in some 
places, with Corylus avellana and Alnus glutinosa. The bed often exhibits 
features which indicate that rapid denudation was going on during its 
formation. The upper layers of peat contain no trace of forest, thiek beds 
of Scirpus and Eriophorum vaginatum peat lying at the Upper Forest horizon 
instead of Pinus silvestris. 
According to Samuelsson (l.e. p. 215) a section close to the road, about 
4 km. south of Barvas, showed the following strata :— 
A. 200 cm. of Eriophorum vaginatum peat, also containing Seirpus 
cies pilosus remains, not decayed and entirely without any remains of 
trees, but with solitary Calluna stems, 
B. 25 em. do., highly decayed, very rich in trunks and twigs of birch and 
heather. 
C. 50 em, do., with solitary remains of dwarf shrubs, 
