NOTES AND QUERIES. 73 
in the gradual deterioration of the forest land. Doubtless forest 
trees have the power of extracting nourishment from a larger 
area and a greater depth of the earth than have agricultural plants, 
but the nourishment so obtained is small in comparison with 
that which they get superficially from the mould formed by the 
accumulation of their own leaves. This leaf-mould is the natural 
manure of forest trees, and should not be removed, It is not 
alone the manurial constituents of leaf-mould that make it of 
value ; the physical effects it produces are of perhaps even more 
importance, and chief among these is its power of absorbing and 
retaining water, and of regulating the temperature of the soil, 
whereby the trees are sheltered from extremes of heat and cold 
and of wetness and drought. 
Below the moist covering of leaf-mould, in all stages of forma- 
tion, there is a mild, moist atmosphere, rich in carbonic acid, 
whose effect is to hasten the disintegration of the subjacent rock, 
whereby it is caused to yield up its mineral matter, and contribute 
to the formation of a soil whose fertility is slowly but steadily 
increasing. A. P. Arrxen, M.A., D.Sc., 
Honorary Consulting Chemist to the Society. 
THe CONNECTION BETWEEN GEOLOGY AND FORESTRY. 
In the practice of forestry it is inevitable that questions should 
arise in which an acquaintance with geological science should 
prove a valuable assistance. The forester, like the farmer, applies 
his labour to the soil, and only if that soil be suitable will his 
labour be repaid. It is important, then, for him to understand 
the methods by which the soil is formed, and the geological 
agents which effect the decomposition of the solid rocks. And 
as the soil depends on the rock which underlies it, different rocks 
yielding different soils, the forester must often require to know 
on what formations his land is situated, a point which only a 
geologist can satisfactorily settle. Of rocks, as of soils, a chemical 
analysis is often of the greatest value; but without a geological 
examination much of its value is lost, and it may even prove 
misleading. The same chemical substances, in very much the 
same proportions, may exist in two rocks which yet are entirely 
different for all practical purposes. It is only by a very gradual 
