68 VEGETATION OF THE PEAK DISTRICT [cH. 
The ash woods on the limestone slopes have the same 
altitudinal range as the oak (Quercus sessuliflora) woods on the 
slopes of the sandstones and shales; that is, they range from 
the valley bottoms up to about 1000 feet (305 m.). 
Semi-natural Woods and Plantations 
on the Limestone Slopes 
Some of the slopes of the limestone hills with a deeper and 
a damper soil are utilized by the foresters for the growth of 
marketable timber; and the beech (*Fagus sylvatica), the 
sycamore (*Acer Pseudoplatanus), the larch (*Larix decidua), 
and other trees are planted. Owing to the dip of the rock-strata, 
one side of narrow valleys is usually damper than the other; 
and hence it is unusual to find that the opposite sides of the 
dales have quite similar vegetation. One may find, for example, 
that the damper slope is planted up with beeches, sycamores, 
larches, and other introduced trees, and that the opposite side 
is characterized by a perfectly spontaneous ash wood; and thus 
it is in parts of Lathkilldale. In some cases, where alien trees 
have been planted on the site of a previous ash wood, the 
primitive flora lingers on for some time. For example, the 
lily-of-the-valley (Convallaria majalis) and the broad-leaved 
helleborine (Helleborine latifolia) still linger on, but do not 
flower freely, under introduced beeches in Lathkilldale. In 
other cases, the alien trees have been planted on calcareous 
grassland. In such plantations, one does not find the rarer 
and more characteristic plants of the ash woods; but some 
of the more general and ubiquitous woodland species, such 
as Geum urbanum and Lychnis dioica, sooner or later invade 
them. On the accompanying vegetation maps, the great 
abundance of introduced trees is, where possible, indicated by 
the initial letter of the alien tree being planted over the wood- 
land colour; and thus it is often possible to infer from the maps 
whether alien trees have been planted in a wood or not. The 
maps, therefore, have a far greater value to foresters than any 
previously constructed maps, such as the Ordnance maps or 
the small scale maps issued by various publishers, as even the 
best of these maps do not attempt to distinguish more than 
deciduous woods and coniferous woods; and even this simple 
