6 ORIGIN OF VEGETATION IN NITHSDALE. 
small proportion of its area. This old Silurian tableland 
plastered with boulder clay in places is almost everywhere capped 
by peat 10-17 feet thick. 
Now, the point which I wish to make is that these moorlands 
are a tableland and flat so that natural drainage is difficult. 
Thus on these flatter summits the Blaeberry-Grass-Heath would be 
subject to the attacks, especially of Cotton Grass, Deer’s Hair, and 
Sphagnum moss, which would eventually kill out the Blaeberry 
and Grasses, and in many places the Heather, though this last 
might remain on dry rounded “humps.’’ Thus peat might be 
produced and go on forming as it has done until to-day. But 
was there never anything else in Dumfriesshire? Remains of 
Scotch fir exist in the Highlands up to 1800 feet, where the great 
Silva Caledonica of Pinus Silvertris existed in Roman times. 
Lewis found Scotch fir remains on Crossfell in Yorkshire at 2500 
feet, which are probably the great trunks recorded by Winch in 
1825. Birch does occur in the mosses, but I have no record of 
remains of Pine even at 1400 feet. But I think that these remains 
will be found. At Kirkconnel this summer I was shown hundreds 
of little Scotch fir seedlings thriving on a dry peat moss of the 
most typical character, and some had become quite respectable 
trees. When the Blaeberry-Grass-Heather Association was 
attacked pretty soon by the Pine forest with its attendant Rowans, 
Birches, Bracken, Bluebells, and others, the result would be to 
form an enormously greater amount of good fertile soil. The 
next crowd of immigrants, the Oak, Beech, and their attendants, 
ferns and flowering plants, would then invade and dispossess the 
Pine forest, so covering lowland Scotland with the historic Oak 
forest. 
I do not wish to say that the process here sketched was 
invariably the same. On steep slopes one may see, even now, 
that the Blaeberry-Grass-Heather Association has been altered to 
permanent pasture by the Nardus, Airas, and Fescues suppressing 
the other members. 
So also in Lochar Moss, and in most of the fertile alluvial 
holms, the Arctic water plants, such as the Reeds and Grass 
Seeds, probably began to act very soon after the glaciers retreated, 
as they may be seen at work to-day. With the aid of Willows, 
Alders, and marsh plants, they are retaining the silt and floating 
stuff, changing shingle, mud, and sand into valuable pasture and 
arable. 
