ON THE PLANT REMAINS IN THE SCOTTISH PEAT MOSSES. 355 



the same sequence in the upper layers, — first Sphagnum moor, then pine forest, 

 changing to Sphagnum, Eriophorum, and Scirpus moors, which last persist down to the 

 present time. The impression given by these deposits rather suggests the occurrence 

 of a dry genial period during the deposition of the younger peat-beds, due to secular 

 changes in conditions which must have affected the whole of North-West Europe. 



The general sequence of events on the Spey-Findhorn watershed is illustrative of 

 what happened in other districts in Inverness-shire, East Ross-shire, and Caithness-shire. 

 The peat in all these districts tells the same story : it begins its history under Arctic 

 conditions, which later change to sub-Arctic, continues its growth under a milder but 

 much more humid climate, ceases to form whilst clad with thick forests of pine, and 

 again continues to grow down to the present time under the influence of a moister 

 insular climate. 



The type of Arctic vegetation found at the bases of these mosses may be briefly com- 

 pared with some of the plant formations described by Warming ( 1 ) from Greenland. The 

 general facies of the vegetation which occurs in the " oseraies " bears some resemblance 

 to the vegetation over many of the Scottish areas during the Salix Arbuscula period. 

 In Greenland, however, the typical willow is Salix glauca, L., which from 67°-68° lat. 

 grows to the height of about 2 metres, whilst further north, in about 73° lat., its height 

 does not generally exceed '5 metre. The soil is formed of a black humus, with 

 occasional copses on the dryer ground. Herbaceous plants, amongst which are Veronica 

 alpina, Viola palustris, Carices, and Equisetacese, occur abundantly. Mosses are 

 plentiful, whilst lichens are few in number. This agrees very closely with the general 

 character of the Salix beds near the base of the Scottish peat, — willow is always 

 dominant, along with many mosses, particularly Hypnaceee and Minum pseudo- 

 punctatum, together with the seeds of herbaceous plants, some of the species being the 

 same as those mentioned by Warming. 



The Correlation of the Peat Beds with the later stages of the Glacial Period. 



As the question of glacial and interglacial stages has been referred to several times 

 in this paper, it is perhaps desirable to add a general statement of the glacial succession 

 and compare briefly the corresponding strata found in the peat. 



All the peat deposits examined are post-glacial in the sense that they are of later 

 date than the epoch of district ice-sheets and mountain-valley glaciers. The peat, 

 however, contains evidence that subsequent to its earliest growth cold conditions again 

 supervened, shown by the series in the Southern Uplands, where a widespread buried 

 forest occurs at the base, formed of Betula, alba, Corylus Avellana, along with such 

 plants as Ajuga reptans and Epilobium palustre, L., and overlaid by thick Sphagnum 

 beds, above which comes an Arctic bed of Salix reticulata, S. herbacea, Loiseleuria 

 procumbens, and Empetrum nigrum. There can hardly be any doubt that here we are 

 dealing with climatic changes of an extensive character, and that conditions capable of 

 inducing such an Arctic growth at 1000 feet in the extreme South- West of Scotland must 



