ON THE PLANT REMAINS OF THE SCOTTISH PEAT MOSSES. 827 



localised in one peat moss to a certain horizon of the peat, one has no right, at least on 

 the strength of investigations undertaken hitherto, to parallelise them with another as 

 to time," receives no support from the British peat areas, and in Iceland a continuous 

 layer of trees is found in districts which now lie beyond tree limits. 



In conclusion, I wish to express my thanks to Professor J. W. H. Trail, M.D., 

 F.R.S., for help in determining some of the plants, to Mr H. N. Dixon, M.A., 

 F.L.S., for his identification and remarks on the mosses, and to Dr J. Horne, F.R.S., 

 for much help during the progress of the work. 



I am also greatly indebted to the Government Grant Committee of the Royal 

 Society, London, for grants to defray the scientific expenses of this investigation in 

 Scotland. To the Council of the British Association for the Advancement of Science I 

 owe my best thanks for a grant to defray the scientific expenses of the investigation 

 in Iceland. 



APPENDIX A. 



Stratification of Peat Deposits in Iceland. 



In 1907 I made a journey through parts of Western and Southern Iceland for a 

 preliminary examination of some of the peat areas. No record was available as to 

 position, extent, or depth of the peat ; but from information collected at Reykjavik 

 two areas were selected — one to the south-east, over Hellisheidi, through Reykir, across 

 the Pjorsa River near the farm of Kaljholt, past the Eastern and Western Ranga Rivers 

 to the glaciers of Tindfjallajokull — a distance from Reykjavik of 120 miles in a straight 

 line. The other area embraced three of the broad, shallow valleys south of Reykjavik, 

 within about 8 miles of that place. 



The first part of the south-east route passed over rocky ground with a sparse vegeta- 

 tion of Salix herbacea, Dryas octopetala, Empetrum nigrum, with large areas of bare 

 soil between. About 20 miles from Reykjavik, the Hellisheidi rises to about 1800 feet 

 for a distance of 9 miles. This is covered in most places by peat averaging from 

 a few inches to a foot in depth, and here the vegetation consists principally of Rkaco- 

 mitrium lanuginosum, amongst which grow numerous stunted plants of Calluna 

 vulgaris, Vaccinium Myrtillus, V. uliginosum, Empetrum nigrum, with patches of 

 Salix herbacea. The south-eastern escarpment falls steeply towards Reykir, where 

 peat deposits as much as 5^—6 feet in depth occur on the floor of a broad valley. 

 Sections were taken along the sides of the stream flowing through this valley. The 

 peat is extremely sandy, often traversed by numerous bands of diatomaceous earth and 

 clay, and generally rests upon a floor of lava. There are numerous hot springs along 

 the slopes of the valley, and the frequent bands of clay and iron found in the peat are 

 probably due to the streams of water flowing from these springs during seasons of great 



