ROCK. 



thing we are certain, that the formation of many of the Se- 

 condary ftrata was fubfequent to the exiftence of animal and 

 vegetable life ; were it not fo, their remains could not be enve- 

 loped in them. Another fact is not lefs certain, that many 

 of thefe beds were depofited very gradually, and form a 

 medium in a itate of perfect tranquillity : this is proved by 

 the extremely delicate unbroken fibres and fpines of fome of 

 the organic remains which could not have been preferved 

 entire, had the particles of the itony matter, by which they 

 are covered and imbedded, been of considerable fize, or 

 had they been depofited in a tumultuous element. See 

 Strata. 



Rocks, befide furnifhing the metallic ores, and materials 

 for architecture, have the molt important ufes in the phyfical 

 conftitution, of the globe, not only as forming the folid 

 bafes or fkeletons on which iflands and continents are con- 

 structed, but thefe elevations and inequalities are abfolutely 

 neceffary to fupply the dry land with pure and running 

 ftreams, and to drain the fuperfluity of moifture in rainy 

 feafons, which would otherwife form ftagnant and putrid 

 pools, infecting the air with death : without thefe rocky 

 elevations the earth muft remain a folitary defert, fitted only 

 for the abode of reptiles and amphibious animals. Thus, 

 by the very irregularity and confufion which feem to pre- 

 vail in the difpofition of the fractured furface of the globe, 



of fome parts of this country, as many of the more northern 

 diftricts, and moll parts of Ireland. 



The rocks and (trataof other kinds, from the decompofi- 

 tions of which land or foils have been formed, as well as 

 thofe which conititute the more internal parts of the globe 

 itfelf, have a certain order and arrangement, which is not 

 altogether ufelefs to the inquiring farmer ; efpecially as 

 ftrata of the rocky nature, which are very different in their 

 kinds, not unfrequently happen to be allociated together ; 

 and thofe which are placed directly below the layers of land 

 or foil contain materials, which may, in many cafes, be of 

 utility in ameliorating them. But the general view of the 

 nature, compofition, and pofition of rocks, whether of the 

 primary or fecondary kind, a£ well as of other natural 

 Strata of a fimilar defcription, properly belongs to the 

 general head of rock ; which fee. See alfo Soil and Sub- 

 soil. 



Rock, in Ornamental Gardening, a fubftance or body, 

 which is of much utility in producing effect in the forming 

 and laying out the grounds of country refidences. It is 

 fuggeited by Mr. Loudon, that, though in reality thefe 

 can neither be created, increafed, nor taken away, yet that 

 feveral operations may be effected with them, which feem 

 of the fame nature, and confequently to be of much im- 

 portance in landfcape. They may, it is fuppofed, be either 



it is rendered falubrious and productive, and prepared to Jhe-wn, concealed, or rendered more characlerijlic. They may 

 fatisfy the wants, and gratify the various inclinations and 

 inftincts, of its numerous inhabitants. 



Rock, in Agriculture, a (tony fubftance of different kinds, 

 that frequently affords much interruption to tillage, and is 

 highly injurious as a fubftratum, that occafionally upholds 

 water, and prevents its pairing downwards. Where this lait 

 is the cafe, they are moftly of the clofe, hard, compact 

 kind. They may likewife be hurtful in other ways, as by 

 covering the furface of grafs-land, and by occupying lands 

 which might otherwife produce ufeful plants. Their ef- 

 fects, as non-conductors of water, depends upon their qua- 

 lities, in fome meafure, as well as upon that of the beds of 

 earthy matter in which they are fituated, and will be more 

 fully confidered in fpeaking of SpniHG-draining. The rocky 

 beds of free-ftone, blue-ttone, and lime-ftone, as well as 

 thofe of fome other forts, exift in very different ftates, in 

 different parts of the kingdom ; and are, on that account, 

 more or lefs favourable to the purpofes of hufbandry, in the 

 ground by which they are covered. 



Rocks of particular kinds are not unfrequently instru- 

 mental, in their decompofitions, in contributing to the 



formation of land or foil. Thofe lands or foils which arife, 



in fome degree, from the decompofition of rocks of the fand- 



ftone and granite kinds, are for the moll part of the thin, 



poor, hungry defcription ; continuing for very great lengths 



of time, in many cafes, with but very flight coverings of 



vegetable matter or plants of the graffy fort upon them. 



But thofe proceeding, in fome meafure, from the decom- 

 pofition and mouldering down of rocks of the lime-ftone, 



chalk, and fome other kinds, are in general well and clofely 



befet with plants of the permanent grafs kind, and give, 



when broken up, deep rich earthy beds, for the nourifh- 



ment and fupport of different forts of vegetables as 



crops. 



Where lands are fituated immediately upon beds or 



layers of rocks or ftones, they moftly become dry, and 



fuitable for the purpofes of vegetation, much fooner than 



where they are depofited upon an under-foil of a clayey or 



marly nature. This approach of the rocky ftrata towards 



the furface-beds of land or foil, is probably one great caufe 



pf the fertility of land in moift or wet climates, fuch as thofe 



ii 



be fhewn with more and better effect, by taking away earth 

 from about them, and forming breaks and abruptneffes in 

 the furface of the ground where they are. This may, it is 

 faid, be accomplifhed in many different ways ; but that 

 thofe methods are to be preferred, which are molt effectual 

 in (hewing a perpendicular furface, or upright front of 

 rock ; as it is not only the grandelt manner of feeing them 

 that can be contrived, but, at the fame time, the moft eco- 

 nomical and confident with the good management of the 

 land ; no horizontal furface of any confequence, whether of 

 the wood or pafture kind, being to any material extent de- 

 stroyed. Rocks appear in this way in a great many Situa- 

 tions, in different parts of the country, in the ornamental 

 grounds of refidences. 



It is alfo further fuggefted, that rocks may be fhewn by 

 removing of wood, either alone, or in connection with 

 ground. This practice, it is fuppofed, would often have a 

 fine effect on the fides of hills, mountains, and deeps, as 

 well as upon the banks of rivers and lakes ; in the lait of 

 which cafes, it would frequently be affifted in connection 

 with the removal of water, which can often be effected with 

 eafe : as, for inftance, when a lake has an outlet, or when 

 the channel of a river has confiderable declivity. In all 

 cafes where rocks are to be fhewn, it is conftantly the moft 

 preferable to exhibit erect, projecting, or at leaft nearly 

 perpendicular Surfaces ; as other kinds never occur in nature, 

 except under the lurface of water, or in barren deferts : for 

 although they were originally, or after convulfions of na- 

 ture, left wholly naked, yet by time and circumilances 

 they have gradually become clothed on their upper Surfaces 

 by an earthy matter and vegetable productions. 



Rocks may be concealed, it is imagined, either com- 

 pletely, or in a partial manner, and by any one or the whole 

 of the materials which (hew them. Complete concealment 

 is, however, it is thought, rarely defireable, except in 

 cafes where the rocks are of the barren or difagreeable 

 kind ; as in the inftance of a perfectly naked furface of 

 rocks, or fmall naked angular fragments of them daring 

 through ground of uniform or fimple furface : in the former 

 of which cafes, they fhould be covered with earth ; and in 

 the latter, be blown out of the ground by means of gun- 



powder s 



