ON THE PLANT REMAINS IN THE SCOTTISH PEAT MOSSES. 



351 



beaches. The peat over this area then shows a definite succession of changes. Be- 

 oinning its growth under Arctic conditions, its flora gradually changed to sub-Arctic, and 

 later to a northern type of woodland. After a period of northern woodland, pronounced 

 wet moorland conditions supervened and continued for a lengthy period, until at last 

 the whole area became covered with a forest of Pinus sylvestris. As this decayed its 

 place was taken by Sphagnum. After this a second pine forest appeared, and later wet 

 moorland conditions again supervened, and continued until the present type of flora 

 spread over the ground, which is of a distinctly drier type than that it has replaced. 

 The sequence of plant strata over the present area so closely agrees with that seen in 

 the peat of the Findhorn-Nairn watershed, that the changes referred to have more than 

 a local significance. 



The Findhorn-Nairn Watershed. 



(One inch Ordnance Survey — sheet 84.) — This district lies on the border between 

 Inverness-shire and Nairnshire. The watershed, which runs north-east and south- 

 west, consists of smooth rounded hills rising to an elevation of 1500 feet to 2000 feet, 

 and in general topographical characters is similar to the Findhorn-Spey watershed lying 

 to the south-east. The hills, however, are more rounded and the summits are flatter. 

 After the field work for the Spey-Findhorn watershed had been completed, observations 

 were carried on over this area, with the view of comparing the history of the peat in 

 the two districts. Sections were taken chiefly on the watershed lying between Beinn 

 Bhuidhe Mhor, Cam nan tri tighearnan, and Cam a' Mhais Leathain. The peat between 

 these three summits has been much denuded, and the upper forest zone (pine) can be 

 traced along the sides of the peat-hags. Section I. was taken near the head of Dalreoch 

 Burn, at about 1250 feet, and showed the following strata : — 



Dominant Plants. 



1. Sphagnum. 



2. Pinus sylvestris, L. 



3. Sphagnum. 



4. Pinus sylcestris, L. 



5. Eriophorum and Sphagnum. 



6. Betula alba, L. 



7. Empetrum nigrum, L. 



8. Saliz Arbuscula, L. 



9. Closely packed angular stones, with clay below 



containing large boulders. 



1. 



2. 

 3. 



4. 

 5. 

 6. 



Accompanying Plants. 



Calluna vulgaris (scarce). 



Scirpus, sp. (abundant). 



Calluna vulgaris, L. (fairly plentiful). 



Calluna vulgaris (very abundant). 



Sphagnum and Eriophorum. 



Menyanthes trifoliata, L. 



Viola palustris, L., Arctostaphylos alpina, Spreng. 



Empetrum nigrum, L. (traces). 



Some six sections were taken in all, which showed the same succession of dominant 

 plants. Other sections taken lower down showed that the birch zone rested directly 

 upon the glacial deposits, the older beds being absent. This absence of the lower beds 

 frequently occurs in different districts, and simply means that the peat in those places 

 had begun to grow at a later date. It is important to notice, however, that in such 

 cases these newer beds always show the same sequence as we find in places where the 



TRANS. ROY. SOC. EDIN., VOL. XLV. PART II. (NO. 13). 49 



