THE FORMATION OF PLANTATIONS, 109 
over the ground, and the subsoil noted down. The soil is rarely 
found to be of the same nature over any large area, and therefore 
the species should be distributed so as to suit the different. soils, 
according to the elevation, exposure, etc. 
All soils may be roughly divided into three classes, viz.— 
argillaceous, arenaceous, and calcareous, all presenting fertile and 
infertile examples, according to their mechanical condition, com- 
position, and depth, and an attempt will be made.to briefly show 
the most suitable trees for each class. 
Argillaceous.—These consist principally of silicate of alumina, 
and vary from pure clay to strong loam. These soils are especially 
adapted for growing hardwoods, such as oak, ash, hornbeam, 
poplar, etc., and all trees that delight in a strong damp soil, On 
the stiffer and wetter kinds the ash does not succeed so well as 
the other three. When resting on a bed of sand or gravel, they 
suit ash and sycamore better than most soils, and the addition of 
calcareous matter makes a soil highly favourable to ash and spruce. 
A mixture of clay and gravel suits spruce, silver fir, and larch, 
providing the drainage is good; but, generally speaking, these 
soils are not suitable for growing coniferous timber, as although 
the trees grow rapidly when young, they are usually short-lived, 
and rarely produce good quality of timber, being too coarse and 
soft through rapid growth. 
Arenaceous.—Silica forms the chief constituent of these soils, 
and they are usually dry and porous. Nearly all species belonging 
to the pine genus do well on these soils. In this country the Scots 
fir is the prevailing tree on them, and generally produces better 
timber than when grown on clay or chalk soils. Wherever the 
heather abounds we may generally assume that the Scots fir 
is the most profitable tree to plant, as such ground is usually poor 
and sterile, and in which few trees will thrive, but which produces 
a cleaner growth and more durable timber in the Scots fir than 
soils that are conducive to a rapid and luxuriant growth. The 
more fertile soils of this class suit the beech, elm, maple, and 
Durmast oak, but they must be of a fair depth and open nature, 
so as to allow the roots to penetrate freely in all directions. When 
moderately damp, or when resting on a clay subsoil, larch thrives 
well on all soils of this description, but when too dry and arid it is 
subject to dry rot ; and the same may be said of spruce and silver 
fir. Pure sand is affected by drought less than any soils, but is 
usually too deficient in plant food to bring timber to maturity. 
