THE GEOLOGY OF ORKNEY. XCill 
the peat-bogs in Caithness, gives the following as the 
general succession of the deposits :— 
5. Moorland peat. 
4. Pine forest layers locally in the centre of the 
county, but not on the highest part of the 
plateau nor on the coastal region. 
3. Moorland peat with Sphagnum, Eriophorum, 
&e. 
2. Birch layers widely spread in the county. 
1. A basal layer of Salix arbuscula. 
The second Arctic Bed of Shetland, which should 
occur between the two forest layers (2 and 4 of 
the above succession), has apparently not yet been 
recognised in Caithness. In the south of Scotland, 
however, this bed is well developed, and contains 
Salixe reticulata, Salia herbacea, Loiseleuria procum- 
bens, Arctostaphylos alpina, and other plants. 
CONCLUSIONS. 
Professor James Geikie,' in his investigation into 
the history of the Glacial Period, has arrived at 
certain general conclusions that are strongly supported 
by Mr Lewis's researches into the Scottish peat- 
mosses. In fact, we may say that the significance 
of the Forest Beds was first of all recognised by 
Professor Geikie. Many years ago he pointed out 
that the Forest Beds indicated a climate much more 
genial than the present climate of Seotland, while the 
1 «The Glacial Succession in Europe,” Trans. Roy. Soc. Edin., 
vol. xxxvii., 1902, p. 127. ‘‘ The Great Ice Age,” 3rd Edition, 1894. 
‘‘From the Ice Age to the Present,” Scot. Geog. Mag., vol. xxii., 
1906, p. 397. 
