I'ilE FARMER'S MAGAZINE. 



309 



[LiGN. 7.— Section ofrtisturbed strata by inlrusions of volcani': 

 trap-rock in Kadnorstiire.J 



than that at which they could have possibly been de- 

 posited ou the shore. We further liad that, as in the 

 cases of mountain ranges, such as those to which we have 

 already alluded, the beds are frequently inclined at a very 

 steep angle, and even, it may be, nearly vertical, by the protru- 

 sion of a peak or mass, of a mineral character very different 

 from any presented by the rocks which have been ruptured or 

 disturbed. The protruded masses are usually considered lo be 

 the productions of those volcanic or igneous powers seated deep 

 in the earth, to which are attributed the various elevations and 

 depressions which the superficial striitifled crust of the globe 

 has undergone In arguing upon such facts, and drawing 

 the natural inferences, that there are two classes of rocks, 

 aqueous and igneous — that the hills and mountains and plains 

 have been subjected to various changes of levels — and in fol- 

 lowing out all the phases of concomitant events incident to 

 such changes, and of which we possess or obtain any founda- 

 tion in actual facts, we are illustrating the kind of investiga- 

 tions which I include under the head of Tlieoretical Geology. 

 Under tlie broadest acceptation of this term I include also 

 those established or proven conclusions which constitute the 

 principles of the science, and may be regarded as geology pro- 

 per. By Practical Geology I mean the actual applications of 

 the science to the waats and services of mankind. Economic 

 Geology is synonymous with the teroa " practical" only to a 

 limited extent, because under that head I shall include many 

 things which would not fall correctly within the meaning of the 

 word " economic ;" as, for example, the methods of investigating 

 or observing the properties or conditions of mineral matter, or 

 of actual phenomena, thu determination of the dip or strike of 

 a bed of earth, the construction of maps and sections, and si- 

 milar operations — all of real and practical utility. 



Books are not written so much for the learned as for the 

 ignorant ; a man does not require to read that which he knows, 

 although he may be benefited by being reminded cccRsionally 

 of some of those facts with which ha may once have been fa- 

 miliar ; and while we may have great attainments and knc.v- 

 ledge in one or more special departments, we may be ignorant 

 of some — nay, even many — others. It is net so much to those 

 who Jiave applied the science of geology, as to those who have 

 not applied it, that the remarks and discussions we are con- 

 templating should be addressed ; and therefore a short but lucid 

 explanation of some of the technical terms, and of the more 



important of the accepted principles of geology, although such 

 may be found in most of the popular treatises on this science, 

 will neither be out of place here nor useless ; but that, ou the 

 contrary, we can not only place before the reader who may be 

 interested in these pages, without the trouble of reference, the 

 necessary information he may require for the comprehension of 

 the subject, but we can also, at the same time, illustrate the 

 practical application of many matters which may be great in 

 their results and benefits, although simple in themselves. I do 

 not wish to explain terms or principles so much in the way of 

 a treatise or a dictionary, as to put them, as it were, into prac- 

 tice ; to take them incidentally in our progress, and to treat 

 only of those which are connected with our subject. 



In viewing the great masses of mineral substances, as they are 

 presented to us at I he surface of the globe, we perceive the most 

 important, and by far the largest proportion of them, to consist 

 of various compounds of three familiar bases — lime (calcium), 

 clay (alumina), and flint (silex) — and that in volume the members 

 of the two latter groups each exceed that of the first ; in point 

 of fact, that the sands (including the sandstones, which are only 

 consolidated sandj) and the clays are more numerous and of 

 greater aggregate thickness and extent than the limestones. 

 At first sight the granitic and basaltic rocks would seem from 

 their texture to offer other materials as bases, but analyses 

 have proved that alumina and silex enter largely into their 

 composition ; and the three divisions indicated will really in- 

 clude the great bulk of the mineral substances of \<hich at 

 least the exterior portion of the globe consists. No one can 

 dispute for a moment that the study of the formation of these 

 subslances, their qualities and uses, their position, dimensions, 

 localities, their absorptive and retentive properties, and the 

 various other circumstances connected with them, falls not only 

 within the proper range of geological inquiry, hut that it can- 

 not be pursuecj without eliciting numerous facts of great prac- 

 tical utility and application. To the architect and engineer 

 the results so obtained are invaluable, and their utility bo 

 palpably evident that no professional man of any note is now 

 without some knowledge of geology. Such investigations, it is 

 evident, must convey much and important knowledge of the 

 qualities of building stones, of clays for bricks, of the action of 

 springs, the supply of water, and a variety of other matters of 

 a practical nature; but the connection between agriculture 

 and geology seems to have been very much overlooked, or 

 greatly neglected, and while modern farmers have more or leas 

 appealed to the chemist, they have not so generally consulted 

 the geologist. To show the practical application then of this 

 science to agriculture is, as I have said before, the object of 

 these papers. 



In our next lecture we will take a brief view of geology in its 

 grand results and principles, and of the varied phenomena 

 by which the most important features in the structure of the 

 exterior portion of our globe have been produced. 



THE HIGHLAND AND AGRICULTURAL SOCIETY OF SCOTLAND. 



MEETING AT ABERDEEN. 



" How comes it," asks the general visitor, " that the 

 Meeting of the Highland Society is this year a month 

 later than usual?" " How is it," comments the more 

 caustic critic, " that by some especial arrangement the 

 Show is this season celebrated just in the very height 

 of the Northern harvest !" Any injudicious collision, 



as heretofore, with the fixtures of other Societies, might 

 be something of an answer. For instance, by avoiding 

 the custoniary clash with Yorkshire, the Scotch Exhi- 

 bition has been materially strengthened by the entries 

 of cattle, sheep, and pigs, which under other circum- 

 stances would not have been here. This, however, is 



