PLANT REMAINS IN PEAT MOSSES 309 



are not sufficiently moist to favour peat growth ; for the upland 

 valley, hill-side, and hill-top peat, almost without exception, is 

 in a state of rapid denudation, being traversed by channels and 

 furrows often 12 or 15 ft. in depth. If the sides of these gullies 

 are examined, the stems and roots of large trees are often seen 

 exposed as the bank is gradually cut back by the stream at its 

 base. Where the peat is deep and the stream has cut its way 

 down to the soil, it becomes evident that the tree-roots and 

 stems are arranged in a definite layer. Sometimes one, more 

 frequently two, and occasionally three such forest beds can be 

 recognised, separated by thick beds of peat quite free from any 

 traces of trees. These forest remains are frequently present in 

 the peat in districts where no trees will grow at the present 

 day ; to take but two instances, forest remains are abundant in 

 the peat of the now treeless Hebrides and Shetlands, and on the 

 summits of the Grampians at more than 3,000 ft. above sea-level. 

 The great thickness of many of our peat deposits (sometimes 

 reaching 30 — 50 ft.), the known slow rate of growth of peat, 

 and the general presence of two forest beds, is evidence that the 

 conditions have changed considerably since the mosses began to 

 form, and a closer examination has shown that large areas of 

 peat in Britain date back to the later phases of the glacial 

 period. 



All the peat areas examined in Scotland lie some distance 

 from crofts or villages, and the strata show no sign of having 

 been disturbed by human agency. Sections are cut down 

 through the successive strata until the underlying rock, gravel, 

 or sand deposits are reached. Each section is made just large 

 enough to work in conveniently. Over areas where the peat is 

 of moderate depth, the sections are usually 8 or 9 ft. in length 

 and 4 ft. wide. In some districts, such as the Shetlands, where 

 the peat is frequently 18 — 19 ft. in depth, the sections have to 

 be made 17 — 20 ft. in length, to allow a series of platforms to be 

 left at each end, upon which the peat from near the base of 

 the section can be placed. In some of the areas a good deal 

 of difficulty is experienced in cutting through the Upper Forest 

 of pine. The timber proves to be so large and tough, and so 

 closely packed, that it is impossible to cut through it with a 

 spade, and it is necessary to clear away the large trunks and 

 roots of the pine with the aid of an axe and saw before the 

 underlying peat can be excavated. 



