THE PEAT CLISTASE. 



391 



plants have been found at the base, the basal vegetation consisting of shrabby 

 birch, which is continuous over the area. The beds above this represent lake 

 or swamp conditions; but a return to forest conditions took place later, when 

 the mosses became fringed with pine trees of large size. The peat above the 

 pine zone is formed of wet-condition moorland plants. 



"The mosses lying on the 25-feet raised beaches contain no Arctic plants, 

 and the general facies of the vegetation agrees with that in the upper layers 

 of the older mosses inland. The basal layers consist of birch, hazel, and alder, 

 which give place above to wet-condition plants such as Sphagnum, Eriophorum, 

 and Phragmites. 



"Birch is represented in the basal layers of all the Scottish mosses described 

 in this paper, and birch has also been found in the lower layers of some of the 

 Highland peat." 



Cayeux (1906), in the investigation of litoral deposits in France, has found 

 three layers of peat separated by layers of marine sandy alluvium: 



The lower layer rests upon solid sand, and comprises two levels. The lower 

 consists of reeds in position, and represents the bed of a swamp; the upper 

 contains transported branches and bark of birch, poplar, beech, etc. The 

 middle layer represents a second reed-swamp, with many plants of Phragmites 

 rooted in places. The upper layer is found between two sandy ones, corre- 

 sponding to submersions by the sea; it represents a forest floor with the trunks 

 still in position. The study of these layers is regarded as showing that peat 



may be formed of transported or sessile plant remains. 



• 



Levxis (1906 : 352; 1907 : 66) has summarized the successional evidences 

 furnished by the peat of the Scottish Highlands and the Shetland Islands 

 (figs. 41, 42): 



Glacial succession 



SreV-FINDHORK WATERSHIO 

 1800-2100 FT. 



COLRE BOO EASTER ROSS 

 1 400 FT. 



FiNDHORN NAIRN WATUSHtO 



1900 rr. 



Upper forestian 



OR 

 STH.INTtRGLACIAL 

 ^-, STAGE 



WWERTURBARIAN 



OR 

 5TH.6LAC1A1.STASE 



Recent put chiefily 



Scirpus and 

 Sphagnum 



Pinussylvestris 



Sphagnum 

 Pinussylvestris 



Sphagnunn 



and 

 Eriophorum 



Petulaalba 

 Empetrum 



Salix arbuscula 

 Arctostaphj/los 

 alpina 

 Sali>l: reticulata 

 Sherbac&a 



"' • «..'" 



Recent peatchie.f ly 



scirpus and 

 Sphagnum 



Pinus sylvestri? 



Spha«|num 

 pinus sylvestris 



<X.^ 



Sphagnum 



and 

 Eriophorum 



B&tulaalba 

 Lmpe.trum 



Salix arbuscula 

 Ketulanana 

 Dryas octopetala 

 Salix reticulata 



Recent peat chiefly 



Scirpus and 

 Sphagnum 



Pinus sylvestris 

 Sphagnom 

 Pinus sylvestris 



^pgCica 



Sphagnum 



and 

 Eriophorum 



Betala alba 



Salix arbuscula 



i Fig. 41.— Succession of peat strata in the northeast Highlands of Scotland. After Lewis. 



