GEOLOGY. 



GEOLOGY. 



well observed by Mr. Morton, in his valuable 

 little work on Soils, p. 3. " If we can show an 

 identity of the materials which form the soil 

 with those of the subsoil upon which it rests, 

 we shall obtain a key to a more correct and 

 satisfactory classification of soils than at pre- 

 sent exists; their nature and properties, the 

 kind of crops which they are best calcalated to 

 produce, and the materials necessary for their 

 permanent improvement will also be more evi- 

 dent." That such scientific observances of 

 the order of nature cannot but be attended 

 with benefit, is a remark which we cannot too 

 often make to the farmer: it was an observa- 

 tion which Davy long since made, (Lectures, p. 

 204) ; he told the farmers of his day, that " the 

 best natural soils are those of which the ma- 

 terials have been derived from different strata 

 which have been minutely divided by air and 

 water, and are intimately blended together; 

 and in improving soils artificially, the farmer 

 cannot do better than imitate the processes of 

 nature ; the materials necesary for the pur- 

 pose are seldom far distant coarse sand is 

 often found immediately on chalk, and beds of 

 sand and gravel are common below clay. The 

 labour of improving the texture or constitution 

 of the soil is repaid by a great permanent ad- 

 vantage less manure is required, and its fer- 

 tility insured, and capital laid out in this way 

 secures forever the productiveness, and con- 

 sequently the value, of the land ;" and again, 

 Dr. Paris, when addressing the Penwith Agri- 

 cultural Society, remarked, "The composition 

 and arrangement of the different rocks of which 

 a country consists, is always an object of im- 

 portant interest to the liberal and well-informed 

 farmer, for it will generally be found more or 

 less connected with its agricultural economy, 

 and is frequently capable of explaining pecu- 

 liarities and anomalies which are otherwise 

 quite unintelligible. At the same time a know- 

 ledge of them will suggest the best method of 

 improving a soil by exhibiting the nature of 

 its texture and constitution, and the various 

 causes of its sterility." That geological sur- 

 veys of even particular estates have been at- 

 tended with considerable benefit, we have the 

 valuable testimony, amongst many others, of 

 Sir J. V. Johnstone, who says (Journ. of Eng. 

 Jlgric. Soc. vol. i. p. 273), "The geological sur- 

 vey and map of my estate has not only ex- 

 plained the reason of the discrepancy between 

 the soil and productiveness of neighbouring 

 fields a matter of great interest, and tending 

 to develope the true conditions of vegetable 

 life but the following positive practical re- 

 sults have been also derived from it : 1st, The 

 knowledge of applying lime to advantage over 

 the property ; 2d, Laying down fields to advan- 

 tage to grass, and where and how to plant 

 wheat; 3d, What trees to plant upon each 

 stratum ; and as, he very correctly adds, "Cer- 

 tain soils are so obviously connected with their 

 bases, that we need scarcely ask how geology 

 and agriculture are mixed together;" and to 

 use Dr. Smith's own words, " The strata suc- 

 ceed each other in a certain order, and being 

 delineated, a knowledge of the strata becomes 

 the natural and safe foundation of improve- 

 ment; and if agricultural chemistry be ever 



successfully applied to the practical purposes 

 of agriculture, it must be by proceeding with 

 the chemical analysis of soils along the range 

 of each stratum." (Farmer's Almanac.") 



And it is quite true, as Mr. Macgillivray re- 

 marks (Quarterly Journal of Agriculture, vol. iii. 

 p. 209), that "an experienced agriculturist 

 may judge correctly of the general capabilities 

 of a district from a superficial inspection, and 

 may perceive its adaptation to the cultivation 

 of certain plants, or to the rearing of certain 

 species of animals, in consequence of a single 

 glance of his eye ; but how much more precise 

 will be the estimate of him who examines the 

 slopes of the declivities ; the depth and quality 

 of the soil ; the nature of the subsoil ; the dis- 

 tribution of rills, pools, and springs ; the kind 

 and disposition of the mineral strata; the ex- 

 istence of limestone beds ; the elevation above 

 the level of the sea ; the exposure to particular 

 winds; the prevalent atmospheric currents; 

 the frequency of rains and frosts ; and all the 

 other physical phenomena which influence a 

 country. Even the nature of the rock itself, in- 

 dependently of other circumstances, discloses 

 the capabilities of the soil, in a degree which 

 could scarcely br imagined by one totally un- 

 acquainted with the influence which it pos- 

 sesses." 



As my observations on geology in this work 

 will be chiefly confined to its connexion with 

 practical agriculture, I shall not detain the 

 farmer with any of the valuable geological re- 

 searches which extend far beneath the earth's 

 surface. Indeed, as Professor Brande remarks 

 in his OtUline of Geology, p. 32, when speaking 

 of geology, " Its first and leading object is to 

 become practically acquainted with the pre- 

 sent state of the earth's external structure, for, 

 excepting of its crust or rind, we know nothing; 

 and all that has been suggested either by theory 

 or experiment, relating to its internal composi- 

 tion, its density, and the constitution of the en- 

 tire mass, is mere surmise and guess-work 

 deductions hastily drawn from superficial ob- 

 servation or unwarranted inferences from im- 

 perfect researches." To the student who 

 wishes to make himself practically master of 

 the science, I commend the lectures of Pro- 

 fessor Brande, as well as the Outlines of the 

 Geology of England and Wales, by Conybeare 

 and Phillips. To the practical, intelligent 

 farmer, the work On Soils, by Mr. John Morton, 

 will also be very valuable. To this excellent 

 little book I gratefully acknowledge my obliga- 

 tions in this and many other articles. 



The best popular description, perhaps, of 

 the position in which the various strata of the 

 earth are placed, is that long since given by 

 Mitchell. "This very ingenious writer," says 

 Brande (Outlines, p. 13), "describes the gene- 

 ral appearance of the strata, points out their 

 analogies and differences, adverts to their in- 

 clination and disturbance in mountainous dis- 

 tricts, and to their horizontality in flat coun- 

 tries ; and having explained with much minute 

 and practical perspicuity the arrangement of 

 the strata in England, he exemplifies its uni- 

 versal application to the general structure of 

 the globe, and ingeniously represents it in the 

 following manner : ' Let a number of leaves 



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