216 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
28. The Woods of Somerset.! 
The publication of a further memoir of the Geographical 
Distribution of Vegetation in Britain adds to our exact know- 
ledge of the nature and distribution of British woods, and is 
evidence that the work initiated by the late Mr Robert Smith is 
being vigorously prosecuted. The district dealt with in the 
memoir is divided into a lowland and an upland area. 
The former consists of recent deposits, and was primitively 
treeless; and even now plantations are uncommon there. The 
geology of the upland area is a matter of great complexity. It 
includes an almost unbroken sequence of strata from the Old 
Red Sandstone to the Chalk, and it might be inferred that the 
vegetation must be equally diverse. Such, however, is not the 
case. Vegetation responds to the substratum in which it grows, 
z.¢., to the soil; and while the soils of the upland area are 
singularly free from recent deposits, and bear a direct relation 
to the underlying rocks, yet those differences among rocks 
and resultant soils which are important to the geologist are 
not necessarily those which affect vegetation. From the 
standpoint of vegetation, it was found necessary to subdivide 
the soils of the upland area into only three classes,— 
sandstones, limestones, and deep marls and clays; and the 
vegetation is considered under these headings. 
A characteristic of the soils of the sandstones is the readiness 
with which a coat of humus appears as a superficial layer, and 
which, when the ground is left to itself, in time develops a 
covering of peat. The ultimate plant association of the sand- 
stones appears to be an oak wood; but most of the primitive 
woods of the district have been destroyed and converted into 
farmland, or have degenerated into heaths or moors. Oak woods 
are recorded as occurring on the Greensand, on the Coal- 
Measures, and on the Old Red and Devonian Sandstones. The 
oak wood region of the Greensand is roughly co-terminous 
with the limits of the ancient forest of Selwood, which originally 
covered about 20,000 acres. On many of the heaths, commons, 
1 Geographical Distribution of Vegetation in Somerset: Bath and Bridgwater 
District, by C. E. Moss, M.Sc. London: The Royal Geographical Society, 
1 Savile Row; Edward Stanford, 12, 13, and 14 Long Acre, W.C. 1907. 
Price, to Fellows, 2s. 6d.; to non-Fellows, 5s. 
