264 



CULINARY OR KITCHEN GARDEN. 



water, and least so when in a thin surface 

 stratum, resting on a dry base. Before, how- 

 ever, treating on these individually, we may 

 offer a few brief remarks on the origin of soils 

 generally. 



" It is the generally received opinion of the 

 formation of soils, that they have proceeded 

 from the detrition of rocks by the force of ex- 

 ternal agencies; that the disintegrated materials 

 have been carried by floods to the ocean, and, 

 there accumulating, are formed into horizontal 

 layers. But the decay of rocks themselves 

 must be very gradual : in some dry countries, 

 inscriptions are perfect, and their angular edges 

 and shapes but little blunted or altered, after a 

 lapse of twenty centuries. The formations that 

 are taking place, in the present quiescent state 

 of the globe, are made by the sea, fresh-water 

 rivers, and by lacustrine deposits from sub- 

 stances collected and rolled along by the course 

 of the waters over the earth. The depositions 

 go on in many places visibly, though slowly : 

 but we know little of the processes by which 

 the vast alluvial deposits have been made, in all 

 the different arrangements, mixtures, and com- 

 binations, to the depth of several hundred 

 feet, and extending over vast tracts of various 

 and discordant qualities ; or of the means em- 

 ployed by nature in the process of alluvial depo- 

 sition from the detritus accumulated at the foot 

 of mountains, from the decomposition of rocks, 

 and of the subsequent removal and consolida- 

 tion, or even of the operations by which animal 

 and vegetable exuvise are converted into soil. 

 But these petrifactions and organic remains 

 would seem sufficient to place one fact 

 beyond dispute, that the globe has undergone 

 many extensive changes; and it is not a little 

 curious that they are confined to particular 

 formations, and are not found in contiguous 

 strata, and that the remains of trees and vege- 

 tables are found only in some few similar situ- 

 ations. Soils are often found to contain sub- 

 stances that do not exist in the rocks on which 

 they rest; and rocks frequently possess materials 

 of which no vestiges can be detected in the 

 upper soil, and which, being destructible, would 

 be found in some degree or quantity, if soils 

 were derived from the adjacent formations. 

 These circumstances would appear to indicate 

 that other agents than detrition have been at 

 work in the production and creation of soils. 



" The alluvial formation constitutes the 

 greater mass of the surface of the earth, and is 

 composed of rocky substances, formed of pre- 

 viously existing rocks, and supposed to be 

 formed by the detrition and ruins of other for- 

 mations, broken down by the gradual action of 

 water. They are loose in textiu'C, and are 

 never covered with any rock or solid secondary 

 strata, and may be reckoned a very recent depo- 

 sition, the formation of which is still going on. 

 The deposit is mostly composed of clay, sand, 

 and gravel, which, in a great variety of combi- 

 nations and modifications, constitute what is 

 termed land or soil. They contain sands from 

 quartz, and clays from the disintegration of 

 slates, felspar, and micaceous rocks, mixed with 

 other substances, and fill up hollow places, and 



form very extensive tracts. They also contain 

 calcareous tuffs, common salt, and peat, subter- 

 ranean and submarine forests, bogs, iron ore, 

 metals, ores, and gems in grains." — Donaldson 

 on Soils and Manures, p. 10. 



This view appears also to have been taken by 

 Mr Morton, who observes in his work on soils, 

 that " the surface of the earth partakes of the 

 nature and colour of the subsoil or rock on 

 which it rests. The principal mineral of the 

 soil of any district is that of the geological for- 

 mation under it. Hence we find argiUaoeous 

 soil resting on the various clay formations, cal- 

 careous soil over the chalk, and oolitic rocks 

 and sUicious soils over the various sandstones. 

 On the chalk the soil is white; on the red sand- 

 stone it is red ; and on the sands and clays, the 

 surface has nearly the same shade of colour aa 

 the subsoil. The lime, potash, and iron, existing 

 in various proportions in the rock, are acted 

 upon by the atmosphere, and the rock is decom- 

 posed; some of it will form impalpable matter, 

 some into sand, and some into coarse gravel or 

 rubble. The surface is composed of the same 

 materials as the subsoil, with the addition of 

 vegetable and animal matter, in every state of 

 decay, internally mixed with it ; and we perceive 

 a change in the external appearance of the sm'- 

 face whenever there is a change in the subsoil 

 below." 



Whitley, in " Application of Geology to Agri- 

 culture," dissents somewhat from these opinions, 

 and asserts that " the ordinary effect of atmo- 

 spheric infiuence does not appear sufficient to 

 produce such changes. We are therefore led," 

 he continues, " to the conclusion that some 

 more powerful and effective agent has been at 

 work; and the phenomena connected with the 

 facts we have reviewed are only consistent with 

 the theory of a vast body of water having, by its 

 violent action, broken and comminuted the 

 earth's surface to a considerable depth, thus 

 holding in mechanical suspension the materials 

 of which the soil and subsoil are composed— 

 the coarser and heavier parts first subsiding, 

 then the clays, and lastly the fine earthy matter. 

 In endeavouring to establish this view of the 

 formation of soil, the decomposition of rocks 

 by atmospheric and chemical agencies must not 

 be overlooked. These causes had probably 

 produced extensive changes before that cata- 

 strophe, whose effects we have just been describ- 

 ing, and to the present time their operation 

 tends to improve and deepen the soil. The 

 crumbling down of rooks by decomposition may 

 be regarded as conservative of the soil, by sup- 

 plying fresh portions to replace those that are 

 constantly washed away." Notwithstanding 

 the attempt to establish this water theory, 

 which is by no means new, Mr Whitley cannot 

 altogether get rid of the theory laid down by 

 Donaldson, Morton, and others. Ansted, in 

 " Geology," vol. ii., follows, although in a more 

 modified degree, the views of Whitley stated 

 above. 



In reviewing these opinions, Mr Henry 

 Stephens, in " The Book of the Farm," we think 

 very justly, draws the following conclusion: "It 

 appears to me the origin of the soil is not so 



