8o 



SCIENCE-GOSSIP. 



on the heavier soils. Other examples are the rest- 

 harrow, the devil's-bit scabious, the sneeze-wort 

 (Achillea ptarmica) and the field sow-thistle. 



Besides the above principal classes of soils there 

 are others of a mixed character or of special kinds. 

 There is alluvial loam and brick-earth, associations 

 of fine sandy and clayey particles with more or less 

 organic matter, forming a fertile soil, with a flora 

 of a mixed and varied character. There is marsh 

 soil, a rich black unctuous mould consisting largely 

 of decayed vegetable matter, and supporting a 

 flora in which rushes, sedges and coarse grasses 

 predominate. There is the sea sand of which I 

 have already spoken, and the salt marshes, with 

 a flora consisting largely of succulent plants, 

 especially species of Chenopodiaceae. The succu- 

 lence appears to be related to the amount of salt 

 present in the soil. Some species, such as Glaux 

 maritima, Aster tripolium and Plantago maritima, 

 which are dwarf and succulent when growing in a 

 salt marsh, are rank and weedy in habit when they 

 grow on the banks of a tidal river in its upper 

 reaches, where the water is only slightly brackish. 

 The different kinds of soil are marked by the 

 abundance of particular sorts of trees. Thus the 

 beech is pre-eminently the tree of chalky soils, 

 though it thrives also on other dry soils, as on the 

 Bagshot beds of the New Forest, the hills of the 

 greensand and the Oldhaven pebble gravels in the 

 neighbourhood of Addington. Among smaller 

 trees and shrubs, the yew, white beam tree, 

 juniper, wayfaring tree and traveller's joy, are 

 chiefly found on calcareous soils. The Scotch fir 

 and other Coniferae thrive best on a sandy soil. 

 The birch also prefers a silicious or peaty soil. 

 Ericaceous shrubs, such as the rhododendron, love 

 a peaty soil and hate lime. The common elm is 

 partial to rich loam ; the wych elm, rocky soil. 

 The oak loves a heavy clay soil. The ash is also 

 frequent on clay, but will grow on almost any kind 

 of soil. Apple trees thrive on a clay soil, and it is 

 said that it is only from orchards on a clay soil that 

 good cider can be made. 



The relationship between the nature of the soil 

 and the presence or absence of particular forms of 

 animal life is less direct than that between the soil 

 and the plants which grow upon it. Considerations 

 of the nature of the soil often fail to explain the 

 curiously restricted habitats of certain forms of 

 animal life, e.g., of some butterflies. Nevertheless, 

 it is clear that, whatever other conditions may be 

 necessary, the presence of a particular animal in a 

 locality must often depend upon the presence of 

 some plant needful to it for food, shelter, or in 

 some other way. Thus the nightingale, which 

 builds its nest of oak-leaves, is especially abundant 

 on heavy soils, on which the oak is the predominant 

 tree. At the village of Havering-atte-Bower, Essex, 

 which stands on a sandy eminence, it is said that 



the nightingale is never heard, though abundant in 

 the clay tract around. In Tennyson's "Harold" 

 this circumstance is ascribed to the influence of 

 the prayers of King Edward ; but we should now- 

 adays be more disposed to look for its cause in 

 the character of the soil and prevailing vegetation. 



Even the distribution of the human species 

 depends largely on the nature of the soil. Thus 

 at the present time the great centres of population 

 in this country are the coalfields where the raw 

 materials of manufactures are to be procured. 

 Excepting London and towns situated on 

 harbours, almost all our large towns are built on 

 or near the outcrop of the coal measures. In 

 prehistoric times, on the contrary, the chief centres 

 of population appear to have been the chalk downs, 

 which were then open tracts, while the lower and 

 heavier lands were covered with forest. On the 

 chalk downs, too, flint was to be had. It stood 

 in the same relation to primitive man as iron 

 to us, and its manufacture was carried on. In 

 mediaeval times, settlements appear to have been 

 most frequent on the lighter and more fertile soils, 

 such as the green sand, oolites, drift sands and 

 gravels. It is on such soils that we find the 

 villages and parish churches closely clustered 

 together ; while on clayey tracts, which were 

 formerly woodlands, or barren heaths and moun- 

 tains, the villages are few and far between, while 

 the ancient parishes are of wide extent. The 

 boundaries of the old parishes are, as a rule, found 

 to cut across, rather than to coincide with, the 

 natural and physical features of the country, with 

 the object of giving to each parish its share of each 

 different sort of land. Thus, in the case of the 

 villages situated at the foot of the chalk escarp- 

 ment, each parish has commonly its strip of chalk 

 down for sheep pasture, its portion of land suitable 

 for the plough or grazing, and its share of what 

 was the forest beyond. The position of the villages 

 themselves is determined mainly by considerations 

 of water supply. In a clay country it is usual to 

 find the villages situated on patches of overlying 

 drift gravel, where water is to be obtained by wells. 

 All the older portions of London which were for- 

 merly country villages and bear old English names, 

 such as Kensington, Islington, Clapham, etc., are 

 thus situated ; while places on the London clay 

 were not habitable until a public water service had 

 been provided. In the chalk plateaux of Hamp- 

 shire and Wiltshire the villages follow each other 

 in close succession along the bottoms of the valleys, 

 where water is to be obtained from streams, springs, 

 or wells. In Northamptonshire, on the other hand, 

 all the villages are on the top of the hills, where a 

 capping of ironsand or limestone rests on the lias 

 clay, and where springs are thrown off at the 

 junction. 



Oakhyrst, Park Hill Rise, Croydon. 



