144 C. E. Moss , W. M. Rankin and A. G. Tansley. 
sub-fossil occurrence in Denmark in the recent but not in the older 
peat. Whether the beech be a comparatively recent immigrant or 
not, it seems that only in the south-east of England has it found 
climatic conditions enabling it to become dominant and to form 
woods, beating the ash, its light-demanding competitor on calcareous 
soils, by reason of the deep shade which it casts. While the beech 
has every appearance of being native so far west as Cornwall, and 
while it flourishes and ripens seed so far north as Scotland, where 
it is often successfully planted on very various soils, it appears quite 
unable to form natural woods outside the area indicated. 1 It may 
however have had its distribution as a wood-former somewhat 
curtailed by clearance of forest on the outskirts of its present area, 
i.e., on the chalk escarpment on either side of the Chiltern region, 
for in Cambridgeshire and Wiltshire indications of natural beech- 
woods are not wanting. 
Even within the present region of dominance of the beech, 
there are signs of failure in the power of natural rejuvenation 
by self-sown seed, though in other places such rejuvenation is still 
vigorously proceeding. It is certain that one very powerful factor 
is the multiplication of rabbits, which eat off the seedlings and do 
as much harm to the beechwoods as they do to the oakwoods. 
And just as birch and pine tend to replace oak on sandy soils when 
the original oakwood is handicapped by heavy clearing and the 
attacks of rabbits, so ash, in some places at least, seems to replace 
beech on the Chalk, when the beechwoods are similarly handicapped. 
For the most part, beechwood stops sharply at the edge of 
the shallow chalk soil. Thus, for instance, the chalk plateau of 
the North Downs is nearly everywhere covered by the so-called 
“ clay-with-flints,” really consisting of varying clays and loams 
which are marked by great poverty in lime. These soils nearly 
always extend to the edge, sometimes over the edge, of the 
escarpment, but invariably stop short of the steepest slope of the 
latter. The “ clay-with-flints ” bears oakwood of the damp or of the 
dry type ; and the transition from this to the beechwood of the 
escarpment or valley-side is very sudden, and corresponds very 
exactly with the change of soil. On the plateau of the South 
Downs and on the rolling chalk plain of central Hampshire, there 
1 It is interesting to notice that the distribution of certain asso¬ 
ciations of land molluscs, which show Continental affinities, 
is limited in a similar way. Helix obvolutu, the most typical 
species of these associations is found nowhere beyond the 
limits of the beech-association. 
