ON THE PLANT REMAINS OF THE SCOTTISH PEAT MOSSES. 805 



the stages since the earliest immigration of the arctic flora tends to show that the 

 survival of the arctic elements in the flora is due perhaps more to the absence of com- 

 petition on the summits than to a lower temperature in such spots. The evidence for 

 climatic change rests more upon the absence of all temperate plants during the arctic 

 stages than the absence of arctic-alpine plants during the forest period. 



(c) The Island of Foula. — This is a small island 3 miles long and 1\ broad about 25 

 miles due west of Shetland Mainland. The sea between the island and the Mainland is 

 deep, varying from 50 to 100 fathoms. Owing to bad weather, only four days could 

 be spent on the island last season, as communication is only possible in moderate 

 weather ; and this time proved too short to make as complete an investigation as the 

 interesting character of the peat deserved, but the results are so important that 

 they are given here. 



The island, despite its small size, is hilly, the ground rising to 1126 feet on Hamna- 

 feld, 1373 feet on the Sneug, and 1220 feet on the Kame. The east coast is bounded 

 by cliffs 50 to 100 feet in height, and the land does not rise above this level until the 

 centre of the island, where it rises abruptly to a general level of 1200 feet. The west 

 coast is formed by a magnificent range of perpendicular cliffs facing the Atlantic, varying 

 from 700 feet at the Noup to 1220 feet at the Kame. The highest hills appear to be free 

 from glacial drift, but the lower ground is covered with boulder clay overlaid in some 

 places by a considerable thickness (up to 7 feet) of sand and clay (without stones), 

 which appears to be of fresh- water origin. Peat covers all the lower part of the island 

 except where it has been cleared for fuel, and also occurs up to 1200 feet on Brustins 

 and Tounafeld. Time did not permit of sections being made at the highest altitudinal 

 limit of the peat, but sections were taken in the neighbourhood of Flick Lochs (600 feet), 

 Bark Hill (700 feet), and on the lower ground on the east of the island. 



The vegetation is of a more hygrophilous type than on the mainland, Eriophorum, 

 Scirpus, and Sphagnum covering most of the peat areas. Sphagnum occurs plentifully 

 even on the steepest hillsides, such as Hamnafeld, where a rise of 900 feet takes place 

 in 1960 feet, or a slope of about 1 in 2. Only a few inches of peat is formed, but the 

 whole hillside is covered with patches and strips of Sphagnum. The narrow plateau on 

 the west of the island running out to the cliffs is chiefly occupied by pasture, Nardus 

 st7'icta, Molinia cserulea, Festuca ovina, Poa alpina var. vivipara being the chief 

 grasses. A few plants of Lychnis diurna were noticed, curiously dwarfed ; for although 

 in flower they were not more than 2 inches in height. Armeria vulgaris forms a very 

 characteristic feature in the vegetation, especially on the west side, growing in mats 

 some yards in diameter, and in some places forming 2-3 feet of peat. Several alpine 

 plants occur on the higher hills above 1000 feet, Salix herbacea being plentiful, with 

 Loiseleuria procumbens, Polygonum viviparnm, Arctostaphylosalpina. The popu- 

 lation of the island is about 198, and is gathered entirely on the eastern side, the 

 chief collection of crofts being Hametoun in the Daal, on the south-east of the island. 

 In this district the peat has been much cut for fuel, as coal is quite unknown, and large 



