292 Arboriculture m relation to Geology. 



and poverty-stricken appearance which is too often manifest, 

 notwithstanding that heavy expenses have been incurred, when 

 the planter has rather considered what trees he should like to 

 see grow around him, than what trees the land is most con- 

 genial to [see Vol. VII. p. 373.], or has given a general order 

 to his nurseryman, leaving him to supply whatever is most 

 abundant, or best grown, in his own stock, without giving him 

 the necessary information as to the soil, situation, or climate, 

 in which the plantations are to be made. 



The soils to which my observation has been principally 

 directed, because I have been most familiar with them, are the 

 calcareous strata, and particularly the chalk ; a stratum which 

 subtends a very considerable proportion of England ; extend- 

 ing, with some intermission, from Beer in Dorsetshire to 

 Flamborough Head in Yorkshire. This rock, though suf- 

 ficiently porous to permit water to percolate through it, so that 

 it is rarely troubled with surface water, yet has, like all other 

 calcareous matter, a very strong attraction for water; and the 

 consequence of these two properties, namely, its attraction for 

 water, and its porous texture, is, that this soil operates as a 

 sponge, suffering the superfluous water to sink down to a lower 

 level, but retaining a quantity of water so closely combined 

 with its own substance, that it will not freely give it out to the 

 heat of the sun, although it long continues to afford a sufficient 

 supply to the fibres of the vegetables which invest it. We 

 accordingly see that the grass and herbage of the chalk 

 downs do not burn up with the summer heat, even under a 

 very high and long-continued temperature : if they appear 

 brown or yellow, the colour is only that of the ripened stalks of 

 the grass ; but the leaves are still green, and the corn and pulse 

 crops on the chalk, even in a dry summer, are less deficient 

 in straw than are the same crops on many other soils ; and 

 they never, through excess of heat or drought, fail of finding 

 a competent supply of moisture below^ their roots, to swell the 

 grain with farina of the best quality. This rock is, for the 

 most part, too compact to admit the roots of trees freely to 

 insinuate themselves into its fissures, until it has first been 

 trenched, or otherwise broken up ; but, as well the detritus 

 which covers it (and which usually consists of a calcareous 

 loam, varying, at different places in its depth, in the pro- 

 portions of silex, of vegetable matter, and of argil, which are 

 mixed with it), as also the chalk itself, when trenched, evince 

 an aptitude for the growth of certain plants usually considered 

 as aquatics, which we are surprised to see flourishing so lux- 

 uriantly in very elevated situations, and far remote from any 

 visible reservoir of water, either on the surface or beneath it. 

 Thus, the abele, or silver poplar (Populus alba), the black 



