AND PEAT MOSSES OF SCOTLAND. 616 



Having alluded to some of the more obvious causes which have aided in the 

 overthrow of our ancient forests, I shall now proceed to discuss what I consider 

 to have been the chief agents in the work of destruction. For this purpose it is 

 necessary that the more striking peculiarities exhibited by a section of a work- 

 able peat moss should be here borne in mind. 



The best peats are " cast" towards the bottom of a peat moss. They show a 

 somewhat close and compact texture, so much so as occasionally to resemble 

 coal. Above this the peat begins to lose its more compact structure, and vege- 

 table fibres may be detected, which on a closer inspection are recognisable as 

 those of a moss. Towards the upper portions of the section this appearance 

 becomes still more conspicuous, and the peat seems to consist almost entirely of 

 mossy fibres. Throughout the section long grasses may be seen, sparingly in 

 the lower portions, but becoming more abundant as we near the top, where twigs 

 of heather begin to mingle with them. The upper surface or crust of the peat 

 moss (a foot more or less in thickness), seems to be made up chiefly of heather 

 and grasses, and such plants as Polytrichum. When peat moss wants this crust, it 

 generally shows a treacherous surface covered with moss, into which the unwary 

 pedestrian may sink deeper than he might have expected. Small areas of this 

 nature are not uncommon, but they may be considered as exceptional cases. 

 Most peat mosses are provided with a crust of heath and grass. This crust is 

 termed " heather-," and sometimes " hill-peat," from its common occurrence on the 

 slopes and summits of hills, where it does not necessarily overlie true moss peat. 

 It seldom exceeds a foot or two in thickness, and ought properly to be considered 

 as turf rather than peat. 



The compact nature of bottom peats is due to mineralisation. But another 

 variety of peat bog appears to show that vegetable matter, the tissue of which 

 has been nearly lost, may be deposited in a peculiar manner under water. The 

 mosses in which this process takes place are termed in Scotland "flows," a kind 

 of bog characteristic of the peat of the low grounds.* The surface of a flow moss 

 is usually flat, or nearly so, frequently showing dark lochans or tarns, the appear- 

 ance of which gives us the key to the history of the flow. Their examination is 

 attended with some inconvenience, owing to the instability of the peat, which, 

 when ventured upon, will sometimes rise and fall with a disagreeable undulating 

 motion. The peat, in short, is a mere pan or crust spreading over and concealing 



* I have, however, observed flow-mosses on the flat col between two hills, and they are also 

 common enough in some valleys, where we have no reason to suppose that they mark the site of 

 lakes. The origin of" flows" in such situations is due to the presence of springs. " Grass and 

 weed," says Dr King, " grow rapidly at the outburst of these. In winter, these springs swell and 

 loosen all the earth about them ; the sward, consisting of the roots of grasses, is thus lifted up by the 

 water. The sward grows thicker and thicker, till at last it forms a quaking bog." In the same 

 manner, " flows" are often extended beyond the limits of the lakes which they cover, by the out- 

 welling of the imprisoned water during wet seasons. 



