1844.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



391 



REVIEWS. 



Geology, Introductory, DeacHptive, and Practical. By David Thomas 

 Ansted, M. a., F. G. S., Prof, of Geology in King's CoIlegB. 

 London : Van Voorst, 1844, 



It is one of the advantages attendant on the establishment of gpolo- 

 gical professorships in the colleges of the University of London, that 

 as the professorships are working ones and not mere sinecures, and 

 as, too, they are addressed to students intended for many active pur- 

 suits, that geology is now being more practically studied, and more 

 practically applied. The engineer, well aware of the intimate con- 

 nection his pursuits have with geology, and deeply interested in it, 

 has hitherto, when willing to apply himself to the study, been checked 

 either by the meagreness of the information most valuable to him, or 

 by the preponderance of matter of a purely technical or theoretical 

 description. Geological works are either of a purely popular and 

 elementary character, or else addressed so exclusively to speculative 

 points or questions of natural history, that the engineer has rarely 

 been able to avail himself of such productions. It is true that in works 

 of a miscellaneous character much valuable matter is to be found ; the 

 writings of Smith, the father of geology, of Delabeche and of Sopwith, 

 abound with practical hints, but the general student either does not 

 know where to find them or has not the time to wade through so many 

 works. In delivering geological lectures to engineering students, it 

 was in the power of the professor to digest and systematize this scat- 

 tered information, and by this proceeding the way was prepared for 

 supplying a still more important want on the part of the engineering 

 profession, a competent test-book on geology. A work was required 

 which should form a good elementary introduction, but carried out in 

 consonance with the advancement of science, and giving a fair view 

 of general principles, without verging too much on mere speculation 

 or giving undue predominance to the theoretical department, while of 

 course it must be so carried out ;is to give prominently all the practical 

 applications of geology to the pursuits of the engineer. Such a work 

 has been undertaken by Mr. Ansted, a pupil of the distinguished 

 Sedgwick, and Professor of Geology in King's College. Mr. Ansted 

 has devoted himself conscientiously to the task, and not merely has he 

 brought to bear upon it his own knowledge, and the latest published 

 information, but he has in many cases held personal communication 

 with eminent geologists, so as to make the work a text book of the 

 state of geological science up to the latest moment of publication. 

 Moreover, Mr. Ansted modestly states that, without pretending to be 

 a practical miner or engineer, he has taken some little trouble to qua- 

 lify himself so far as to be able to appreciate what is required by the 

 practical man, a preliminary too often neglected, though of imperative 

 necessity to form a competent practical teacher. In perusing the 

 work, it appears to us that the author has weU executed his task, and 

 we only regret that it has not been in our power to bestow upon it 

 longer time than we have already done, or to devote more of our space 

 than we do on the present occasion to a review of its contents. It is 

 our intention specially to consider that portion of the second volume 

 which is of practical application, and we shall defer until that period 

 the few remarks we have to make as to the value of this study to the 

 engineering profession ; although, perhaps, they ought to form our 

 introduction, nevertheless we think it more proper in the first instance 

 briefly to illustrate the necessity which exists for such a work in a 

 general point of view. 



Those who have watched the history of geology are fully aware that 

 it is a progressive science. An old text-book on anatomy may be still 

 available, for it is sound as far as it goes, and the general features of 

 the science are unaltered, though more minute discoveries have been 

 made, and increased power of observation has been able to discriminate 

 some of the finer details, such too is the case with regard to most other 

 sciences. Geology, however, has not enjoyed the labours of centuries, 

 it is an entirely new science, founded in our own day, developed under 

 our very eyes, and progressing with the rapid growth of infancy. 

 Every year brings forth some new and most important fact, and every 

 such discovery, as it enlarges the boundaries of the science, throws 

 fresh light on former discoveries, and very frequently necessitates a 

 new classification and new terminology. The unthinking are too apt to 

 complain of this treating words as facts, and not as the representation 

 of facts, they do not well appreciate the nature of either nomenclature 

 or system. Both these are essentially artificial; they are intended as 

 a kind of artificial memory, to enable us better to appreciate the con- 

 nection of facts and phenomena, but not to imply the existence in 

 nature of such assigned classes, tribes or collections. The whole 

 system is entirely artificial; if we collect together in a class or family 

 for our convenience a number of animals or plants closely resembling 

 each other, we are not to imagine there is in nature any dis* 



tinct boundary between several classes. It is diflieult for the na- 

 turalist to draw the bounds between the whale asd the fish, between 

 animal ^nd vegetable nature, yet no one disputes the benefit of the 

 received system of classification, or believes that u line of division has 

 been surveyed, staked out and accurately determined. So, too, in 

 geology, we talk of secondary and tertiary formations, but we are not 

 to believe therefrom that the Author of creation left oft' work and 

 began a fresh and distinct series — the terms are only conventional 

 and convenient. It will readily be conceived, therefore, that any 

 important discovery will enable us to check and revise our existing 

 system of classification, and that it becomes frequently necessary for 

 the convenience of students so to do. Such is the case in every new 

 science, and is particularly so in Geology, and it is essential that com- 

 petent works should from time to time be compiled, which will enable 

 the young student to begin on sound principles, and the old one to 

 correct his previous studies. 



Most of our readers are aware that the classification for some time 

 prevalent went to establish a system of primary, secondary and ter- 

 tiary formations. The granites, syenites, porphyries, and other un- 

 stratified rocks, being generally found as a basis to the strata of the 

 crust of the earth, received the name of primary, it being intended 

 thereby to express that they were of the earliest date. Here, by the 

 bye, we may observe that these questions of classification are not of 

 mere speculative value, but are of great importance to the engineer, 

 the determination of the age of rocks being an important element to 

 enable us to search for coal and other minerals, for slates and building 

 stones, and influencing greatly the nature of the strata in tunnelling, 

 boring, and subterranean operations. Such being the system of clas- 

 sification, recent researches have established that granite and most of 

 the unstratified rocks are of very various antiquity, some indeed being 

 of the earliest date, others however to be found in very recent forma- 

 tions. The establishment of these facts has necessarily very much 

 altered the views of geologists, and these rocks of various dates have 

 been formed into a class by themselves, of crystalline and unstratified 

 rocks, including the igneous rocks, as granites, granitic rocks and por- 

 phyry ; the metamoiphic or altered rocks, as gneiss, micashist, clay- 

 slate, basalt, lava, and trap-rocks. The stratified rocks are still di- 

 vided into three classes, but the first class is now denominated Palao- 

 zoic, a term suggeited, we believe, by Mr. Murchison, and indicating 

 merely the fact " that the strata so called contain the fossil remains of 

 the earliest formed animals." The other great classes are still called 

 secondary and tertiary, though it has been proposed to term them 

 Mesozoic and Kainozoic, In the same way as the general classification 

 has been so modified, the same spirit of improvement has all'ected the 

 minor divisions of the palaeozoic, secondary and terliary formations. 

 The reserches of Professor Sedgwick, in 1831 and l!5o2, followed up 

 by Mr. Murchison, established the fact that an extensive region in 

 Wales exhibited a distinct formation, the relations of which were de- 

 termined, and it was thenceforth formed into a new system, and dis- 

 tinguished by a collective name as the Silurian system. One useful result 

 of this in our own country was to determine the true geological place 

 of the older fossi.iferous rocks of Devonshire and Cornwall, and in 

 America and Russia the application has been still more extensive. In 

 1S3G, Professor Sedgwick and Mr. Murchison examined a group of 

 strata in Devon, that containing the culm measures, the true place of 

 which had been completely misundi-rstood, and the determination of 

 this again led to the establishment of a new system, called the De- 

 vonian System, which in 1839 was recognized in the Rhenish pro- 

 vinces, and subsequently in the Ural chain and in the United Slates. 

 The Wealden System, it will be remembered, was principally deter- 

 mined by Dr. Mantell. The Permian System has been most recently 

 established by Mr. Murchison. Thus each new discovery has ex- 

 tended the boundaries of the science, and advanced it to its present 

 state, and as it is a matter of some interest to our readers to be in 

 possession of the latest and most accurate information, we subjoin a 

 synopsis of the present system of the classification of the fossiliterous 

 strata, although in noticing the first part of Prof. Ansted's work we 

 then also referred to it. 



f The Sub-Silurian and Lower Silurian Formations. {Proto- 



I zoic of Prof. Sedgwick.) 



I. J The Upper Silurian Group. 



PAL/EOZOIC. j The Devonian System and the Old Red Sandstone. 



The Carboniferous System, the Lower New Red Sandstone, 

 |_ and the Magnesian Limestone. 



(-The Upper New Red Sandstone of England, and the Triassic 

 .• System of Germany, &e. 



II. J The Liassic Group. 

 SECONDARY.' The Oolitic System. 



I The Wealdon Formation. 

 LThe Cretaceous System. 



34* 



