ON THE PLANT REMAINS OF THE SCOTTISH PEAT MOSSES. 817 



with great accuracy, and any irregularity in vertical position would rather tend to be 

 magnified than minimised ; but for ease of reproduction for publication the results were 

 reduced to an equal scale, viz. each square equals 6 inches in both a horizontal and 

 vertical direction. The measurements are shown in PI. V. fig. 36. The surface of the 

 boulder clay is level, except at the southern end, where there is a small basin 15 inches 

 deep. The uppermost 11 inches of the drift is very stony, the surface on which the 

 peat rests being almost a stone pavement. The level of the boulder clay was plotted 

 on the diagram by using the surface of the stream as a datum line, as the fall at this 

 spot was very slight. It is not necessary to describe the features presented by the 

 section, as full details are given in the diagram, except to point out that the forest bed 

 occurs as a definite stratum in the peat, slightly thicker in some places than in others ; 

 these variations, however, being very slight, as compared with the total thickness of 

 the peat. The stratum contained the following trees : — Betula verrucosa, Ehrh., Alnus 

 glutinosa, and Pyrus Aucuparia. The causes of the existence and of the disappear- 

 ance of this forest stage will be discussed later. 



The Loiver and the Upper Forest in Kirkcudbrightshire. — The sections occur 

 in a broad valley between the Merrick and the Kells Mountains, and the strati- 

 fication of the peat was described in a former paper (7). The section was cut so as to 

 follow the line of drainage through the peat bogs, the result being a zigzag course 

 148 feet in length. The value of this section is due to the fact that it lies in a part of 

 the country where three important datum lines occur in the peat : the Lower Forest 

 resting on the glacial deposits, with the Second Arctic Bed above, overlaid by the 

 Upper Forest. 



The method of plotting was similar to that described for Shetland. As all the 

 features under discussion are shown on the section (PL V. fig. 35), there is no need to 

 give a detailed description here. The stools of the trees belonging to the Upper Forest 

 are restricted to a definite band in the peat. The wood occurring at a lower level near 

 the upper surface of the Second Arctic Bed, represents roots either of birch or of pine 

 belonging to the Upper Forest. To make this point certain, microscope sections were 

 cut in every case. The two trees found in the Upper Forest are Pinus sylvestris and 

 Betula glutinosa, Fries. Hazel nuts are also present, although not generally in any 

 quantity. The Second Arctic Bed traverses the whole section and varies slightly in 

 thickness, whilst below comes the Lower Forest resting upon the glacial deposits. 

 The denuded surface of the peat is shown in the diagram by the thin line above the 

 Upper Forest. 



The Upper Forest in Inverness-shire. — This section lies at the north-east extremity 

 of the Monadliath Mountains at an altitude of 1345 feet, on the eastern side of the 

 Highland Railway. It is situated in an old basin of the boulder clay which has been 

 entirely filled with peat, now presenting an undulating surface through which the rail- 

 way runs in a cutting 30 feet in depth, giving good exposures of the boulder clay, capped 

 with peat having an average depth of at least 1 2 feet. Exact measurements are, how- 

 TRANS. ROY. SOC. EDIN, VOL. XLVII. PART IV. (NO. 26). 119 



