Dr Davy's Agricultural Discourse. 361 



sisting of beds of chalk, of various clays and of various sandstones ; 

 the larger portion of terrace-like formation, height rising above 

 height in long continued ridges, table lands or valleys of little de- 

 pression intervening, with a foundation generally of calcareous rock 

 or marl, abounding in shells and other remains of marine animals. 



In the part or district first mentioned, there is observable more 

 relation between the soils and the rocky substrata than in the se- 

 cond. Nor is this surprising or inexplicable. Owing to the steep- 

 ness of the hills there, their declivities are powerfully acted on by 

 heavy rains, and there is a constant tendency to the denudation of 

 their sides in consequence. Accordingly, in this part of the island 

 where chalk is the substratum, a white calcareous soil, very little 

 different from chalk, is found at the surface ; where a bed of clay lies 

 beneath, the surface soil is found to be stiff and argillaceous; where 

 sandstone is the basis, there the soil resting on it is often little more 

 than sand. These remarks apply chiefly to the steep declivities of the 

 hills ; less so to the valleys, especially where they open out into little 

 plains. There, there is found a certain uniformity of soil, which, 

 perhaps, may be considered as a mixture of all the several ingredi- 

 ents of the higher regions, washed down by torrents and commingled. 

 It is a well marked alluvial soil, abounding in siliceous sand, con- 

 taining more or less of clay or alumine, with a small proportion ge- 

 nerally of magnesia and lime. It is a soil not unlike that of British 

 Guiana, being similarly derived, but, I believe, is of a greatly better 

 quality, — the girding mountaintains of the interior of British Gui- 

 ana being chiefly of granite, and there being no back ground there 

 of fertile chalk, as here, to furnish a supply of calcareous matter, 

 however small. 



In the other and larger portion of the island, I have said, there is 

 less relation between the quality of the soils and the rocky beds on 

 which they rest. In many places, even on the same estate, there 

 may be found a considerable variety of soil and subsoil ; in one spot, 

 a calcareous marly soil ; in an adjoining one, a stiff clay ; and near 

 at hand to this, a loose light soil, containing a good deal of siliceous 

 sand, and no small proportion of calcareous earth. The principal 

 varieties of soils over this the greater portion of the island, may be 

 conveniently classed under a few heads, according to their composi- 

 tion, on which their nature aud qualities depend, and in which, not- 

 withstanding the remark I have just made as to admixture, some 

 order of distribution is observable. 



On the higher grounds a reddish-brown soil is predominant, con- 

 taining a large proportion of siliceous matter in a very finely divided 

 state, with a certain portion of clay, and an admixture in small quan- 

 tities of lime and magnesia. This soil presents itself even at the 

 edge of the cliff bordering and bounding the smaller hilly region — a 

 situation we are sure, where it could not be brought after the ground 

 on which it rests, coral and shell limestone, was raised from the 



