961 



GEOLOGY. 



GEOLOGY. 



lapse of time, phenomena as important as those of ancient geological 

 date. 



Lazzaro Moro's views (1740) hare the same tendency to recall 

 speculation to the enployment of real causes seen in daily operation ; 

 Buffon (1749) appears to have unsuccessfully attempted the Union of 

 the fundamental view of Leibnitz and the regard for existing agencies 

 shown by Ray ; Dr. James Button, of Edinburgh, rejected all inquiry 

 sis to the beginning of the world, and gave himself up entirely to an 

 explanation of the phenomena visible in the crust of the earth, on 

 the principle of a continual degradation of land by atmospheric 

 agency, the consequent formation of sedimentary strata on the bed of 

 the sea, and the periodical compensation of these effects by the action 

 of internal heat raising the bed of the sea, with the stratified 

 deposits thereon. A continual destruction of the existing land 

 through the agency of water, and an occasional uplifting of new 

 continents from the ocean bed these are the most striking points of 

 the Huttonian theory of the earth. Sir Charles Lyell differs from 

 Dr. Hutton chiefly by recurring to the original form of the speculation 

 as we may conceive it to have existed in the mind of Pythagoras or 

 Aristotle, could either of those men have become acquainted with 

 modern science. For, instead of the occasional occurrence of a 

 violent upward movement of the bed of the sea, the author of the 

 * Principles of Geology,' contends for a continual compensation among 

 the agencies of nature, the perfect equality of modern and ancient 

 physical forces, and the possibility of explaining all, even the grandest, 

 of ancient geological phenomena by causes now acting, and acting 

 with their present intensity. No more definite or general proposition 

 has ever been advanced in geology, and its effects have been every- 

 where evident in the advancement of geological science. 



Geological appearances are usually of a complicated character, and 

 must be analysed into their elementary parts before the inductive 

 process, which requires the comparison of facts agreeing or differing 

 with respect to a certain quality, can be usefully applied. Fossil 

 shells must be distinguished into fluviatile or marine, identical with 

 or different from recent kinds ; rocks must be considered as to their 

 chemical nature, mechanical structure, geographical and other cha- 

 racters, before any valuable inferences can be gathered from them. 

 Though this kind of labour is not discoverable among the works of 

 the Greeks which remain to us, we must not hastily deny that they 

 attempted it In modern times Fracastoro, Palissy, and Steno, by 

 distinguishing the groups of strata; Lister, by discriminating recent 

 and fossil species of shells, and by noticing the geographical relations 

 of rocks ; Woodward, by his industrious collection of specimens and 

 methods of arrangement ; ' Packe, by his remarkable chorographical 

 map of Kent ; Lehman (1756) and Arduino, by their classification of 

 rocks, according to the relative periods of their production ; and 

 Mitchell (1760), by his masterly determinations concerning the rela- 

 tion between the ranges of mountains and the inclinations of the 

 neighbouring strata have stronger claims to grateful remembrance 

 than are due to those who with much labour have merely produced 

 volumes of empty speculation. 



John Gottlob Lehman (1756) may be considered as having the best 

 claim to a clear enunciation and proof of the different age and relative 

 position of classes of stratified rocks. In the French translation of 

 his work (' Trait*! du Physique, d'Histoire Naturelle, de Mineralogie, 

 et de Metallurgie ') he says, " Nothing is more natural than to group 

 all mountains in three classes. The first includes mountains which 

 are coeval with the formation of the globe; the second class was 

 produced by a revolution co-extensive with its surface ; the third 

 consists of mountains which owe their origin to particular accidents 

 or local revolutions." This was not a mere speculation of what 

 might be convenient, for he adds, " The mountains of the first class 

 are high, sometimes insulated in the plains, but generally connected 

 in a chain, traversing considerable parts of the earth. They differ 

 from those of the second class by their elevation and extent, by their 

 interior structure, by the mineral substances associated with them." 



Pallas (' Journal de Physique," 1779), in addition to these general 

 views, maintains that the granitic rocks, then taken as primary, were 

 never formed by water, because they do not occur in beds, nor contain 

 organic remains ; that the secondary mountains were produced from 

 the disintegration of granite ; and the strata of later date, by the : 

 wrecks of the sea elevated and transported by volcanic eruptions and ! 

 ubqpquent inundations. 



To these distinguished authors Werner, professor of mineralogy in I 

 Freyberg (1775), was a worthy successor. The first important addition 

 made by him to our previous knowledge on the subject was contained 

 in his ' Kiirze Klassifikation und Beschreibung der verschiedeuen 

 Gebirgsarten ' (1787), where the mineralogical distinctions of rocks j 

 may be viewed as a completion of the labours of the earlier Swedish 

 writers, Cronstadt, Wallerius, Linmeus, Ac., all of whom had glimpses 

 of the geological relations of the rocks they classified. It does not 

 appear that Werner proposed any views as to the geological relations 

 of rocks in advance of those of Lehman or Pallas till 17UO or 1791, 

 when the doctrine of 'formations' was explained in his lectures, which 

 imlcr'il was a powerful mode of diffusing instruction ; for his amiable 

 manners, disinterested enthusiasm, and various knowledge gave him a 

 strong ascendency over the numerous pupils who, from various 

 lies, flocked to Freyberg. In 1795 Werner had matured his 

 WAT. BMT. DIV. VOL. II. 



views as to the classification of all the stratified rocks, and from this 

 it is easy to estimate the real claim of Werner to a high place in the 

 ranks of modern geology. The great advance made by Werner 

 consists not in propounding the distinctions of great classes of rocks, 

 for this had become a common idea in Europe, but in practically 

 analysing these classes into their coustitutent groups, tracing the 

 order of succession among them, assigning their mineralogical 

 characters to each, and generalising this local truth into the doctrine 

 of formations universally succeeding one another in a settled order of 

 time. Parting from Freyberg with a better method of mineralogy, 

 and a more developed system of the succession of rocks than was 

 previously known, the pupils of Werner carried the influence of his 

 name and opinions over the world, and, unfortunately, the crude hypo- 

 thesis which was connected with the rich truths he taught was 

 embraced with an ardour very disproportionate to its value. 



In France Rouelle (about 1760) had acquired ideas apparently as 

 general, and fully as well supported by local knowledge, as Lehman. 

 His views on organic remains were quite in advance of the time. In 

 England the notices of stratification by Mr. Strachey (' Phil. Trans.,' 

 1719), the Rev. B. HoUoway (1723), and the Rev. John Mitchell (1760) 

 are of great importance. Strachey presents an accurate section of 

 the coal strata of Somersetshire, with reflections on the strata above 

 them, and their geographical boundaries ; Holloway describes the 

 geographical relation of the sand-hills of Woburn and Shotover, 

 yielding fullers'-earth, to the chalk hills on the east, and the oolitic 

 tracts on the west ; but Mitchell enters into a general and masterly 

 discussion on the relation between geological structure and the 

 geographical features of the surface not to be paralleled for fully 

 fifty years. 



Whitehurst must here be mentioned with honour. His ' Inquiry 

 into the Original State and Formation of the Earth,' 1778, is of small 

 value for the purpose he proposed, but it contains important facts 

 towards a right conception of the structure of the earth. His 16th 

 chapter, entitled ' The Strata of Derbyshire and other parts of 

 England,' is full of information, principally derived from the miners, 

 but evidently well methodised in his own mind. How could the 

 geologists of England neglect such passages as these following, which 

 are merely the scientific exposition of truths known for hundreds of 

 years previous by skilful miners in all regions of stratified rocks ? 

 " The arrangement of the strata in general is such that they invariably 

 follow each other, as it were, in alphabetical order, or as a series of 

 numbers, whatever may be their different denominations. Not that 

 the strata are alike in all the different regions of the earth, either 

 with respect to thickness or quality, for experience shows the contrary ; 

 but that the order of the strata in each particular part, how much 

 soever they may differ as to quality, yet follow each other iu a regular 

 succession, both as to thickness and quality insomuch that by 

 knowing the incumbent stratum, together with the arrangement 

 thereof in any particular part of the earth, we come to a perfect 

 knowledge of all the inferior beds, so far as they have been previously 

 discovered in the adjacent country." (Edit, of 1792, pp. 178, 179.) 

 In p. 186 is the following remark in capitals : " N.B. No vegetable* 

 forms have yet been discovered in any of the limestone strata." 



From these notices it is very clear that a distinct perception of a 

 fixed order iu the succession of strata was so prevalent iu the mining 

 districts of England as to attract the attention of the well-informed 

 classes of society. But it is extraordinary that Mitchell, who was 

 appointed Woodwardian professor in 1792 (according to Farey), and 

 by his physical and mathematical knowledge seemed especially able 

 to work out the whole system of English stratification, should, on his 

 retirement from Cambridge to his rectory of Thomhill in Yorkshire, 

 have contented himself with tracing the succession of strata in the 

 north of England, or rather between Cambridge and Thornhill, and 

 communicating the document to Smeaton, without giving it even to 

 the Royal Society, which had published his early papers. Had this ' 

 been done, or had Smeatou known the value of the paper put into 

 his hands, it could not have happened, that of all the able engineers 

 who before 1790 were engaged iu surveys and executing canals, not a 

 man should have attended to information of such singular value in 

 his profession ; nor would Dr. William Smith have been occupied in 

 re-discovering some of the truths which constitute the foundation of 

 English geology. 



The progress of Dr. Smith's discoveries iu geology is easily traced. 

 Commencing his career as a surveyor of land, and afterwards acquiring 

 great employment as a civil engineer, his attention was drawn in 1787 

 to the obvious distinctions in the soils and the subjacent strata of 

 certain parts of Oxfordshire and Warwickshire, which occupied, with 

 regard to one another, a certain geographical relation. In 1790 and 

 1791 the same relative position of the same strata was forced on his 

 attention in Somersetshire, with the addition of a series of coal strata 

 below the oolite, lias, and red marls with which he was previously 

 familiar. Assured by his own observation that the local knowledge of 

 the mines of Somersetshire which Strachey had published in 1719 

 was only a part of the truth, he set himself not to frame a hypo- 

 thesis, but to determine the extent of the regular succession of strata 

 in the vicinity of Bath, drew accurate sections of the strata in the 

 order of superposition, ascertained amongst them a general dip to the 

 cast, marked their ranges on a map of the surface, and in 1794, iu thu 



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