ON THE PLANT REMAINS OF THE SCOTTISH PEAT MOSSES. 829 



In the first valley I found the following sequence : — 



1. Fine peaty sand, 1 foot. 



2. Yellow clay, 1 inch. 



3. Peat containing abundant remains of Carex sps., 1 foot. 



4. Yellow clay, 3 inches. 



5. Hard fibrous peat, 3 feet. 



6. Peat containing much Betula verrucosa, Ehrh., 1 foot. 



7. Peat containing stems and leaves of Salix herbacea, Betula nana, Thalictrum alpinum, Selaginella 



selaginoides. 



8. Surface of weathered lava. 



The stratification in the second valley is as follows : — 



1. Fine brown sand (with a thin layer of black volcanic ash 1 foot 2 inches below the surface), 3 feet. 



2. Peat containing Carex sps., 2 feet. 



3. Betula verrucosa — wood, catkin scales, and leaves, 5£ feet. 



4. Coarse grit with leaves of Betula nana, Salix lanata. 



5. Stiff gray clay, 1 foot, resting on volcanic rock. 



The strata in the third valley, farther south, were as follows : — 



1. Fine sand, 1 foot 6 inches. 



2. Scirpus cxspitosus peat, 3 feet, with a layer of volcanic ash 1 foot below the surface of the peat. 



3. Peat crowded with the remains of Betula verrucosa, Ehrh., 1 foot. 



4. Hard dry peat containing leaves of Betula nana and Salix herbacea, Polygonum viviparum, bulbils. 



Lower layers containing much sand, 2 feet. 



5. Stratified volcanic ash. 



The stratification in these three valleys is exactly similar. In each case a definite 

 birch layer occurs from 3 feet 6 inches to 5 feet 4 inches below the present surface of 

 the ground, whilst the peat above and below is formed of plants which grow plentifully 

 in Iceland at the present day. Before any definite comparison could be made between 

 the stratification in Iceland, and Scotland, a large amount of work would have to be 

 done in the former country. The most interesting feature that is shown by these 

 sections is the presence of fair-sized trees of Betula verrucosa, Ehrh., in a district 

 which is certainly outside the present limit of distribution of that tree. 



The glacial succession in Iceland has been dealt with very fully by Pjetursson 

 (Pjeturss) (18, 19), in several papers, and according to the evidence he brings forward 

 there is no doubt that there have been several distinct stages in the glaciation, separated 

 by warmer periods. The stratification I have recorded suggests that these changes did 

 not entirely cease after the deposition of the last moraine. 



APPENDIX B. 



Mosses determined by H. N. Dixon, M.A., F.L.S., from Various Strata 



in the Peat. 



Mosses other than Sphagnaceae are not usually abundant in the peat, except locally. 

 Mr H. N. Dixon kindly undertook the determination of the species found in the 

 various strata, and has also added notes upon the species and their present distribution 



