at the same time a professorship of the study of geology. The Woodwardian Museum still subsists, a monument of the sagacity with which its author so early saw the importance of such a collection. Collections and descriptions of fossils, including in the term specimens of minerals of all kinds, as well as organic remains, were frequently made, and especially in places where mining was cultivated; but under such circumstances, they scarcely tended at all to that general and complete knowledge of the earth of which we are now tracing the progress. In more modern times, collections may be said to be the most important books of the geologist, at least next to the strata themselves. The identifications and arrangements of our best geologists, the immense studies of fossil anatomy by Cuvier and others, have been conducted mainly by means of collections of specimens. They are more important in this study than in botany, because specimens which contain important geological information are both more rare and more permanent. Plants, though each individual is perishable, perpetuate and diffuse their kind; while the organic impression on a stone, if lost, may never occur in a second instance; but, on the other hand, if it be preserved in the museum, the individual is almost as permanent in this case, as the species in the other. I shall proceed to notice another mode in which such information was conveyed. Sect. 3.-First Construction of Geological Maps. DR. LISTER, a learned physician, sent to the Royal Society, in 1683, a proposal for maps of soils or minerals; in which he suggested that in the map of England, for example, each soil and its boundaries might be distinguished by color, or in some other way. Such a mode of expressing and connecting our knowledge of the materials of the earth was, perhaps, obvious, when the mass of knowledge became considerable. In 1720, Fontenelle, in his observations on a paper of De Reaumur's, which contained an account of a deposit of fossil-shells in Touraine, says, that in order to reason on such cases, Iwe must have a kind of geographical charts, constructed according to the collection of shells found in the earth." But he justly adds, "What a quantity of observations, and what time would it not require to form such maps!" 66 The execution of such projects required, not merely great labor, but several steps in generalization and classification, before it could take place. Still such attempts were made. In 1743, was published, A new Philosophico-chorographical Chart of East Kent, invented and delineated by Christopher Packe, M.D.; in which, however, the main object is rather to express the course of the valleys than the materials of the country. Guettard formed the project of a mineralogical map of France, and Monnet carried this scheme into effect in 1780, "by order of the king." In these maps, however, the country is not considered as divided into soils, still less strata; but each part is marked with its predominant mineral only. The spirit of generalization which constitutes the main value of such a work is wanting. Geological maps belong strictly to Descriptive Geology; they are free from those wide and doubtful speculations which form so large a portion of the earlier geological books. Yet even geological maps cannot be usefully or consistently constructed without considerable steps of classification and generalization. When, in our own time, geologists were become weary of controversies respecting theory, they applied themselves with extraordinary zeal to the construction of stratigraphical maps of various countries; flattering themselves that in this way they were merely recording incontestable facts and differences. Nor do I mean to intimate that their facts were doubtful, or their distinctions arbitrary. But still they were facts interpreted, associated, and represented, by means of the classifications and general laws which earlier geologists had established; and thus even Descriptive Geology has been brought into existence as a science by the formation of systems and the discovery of principles. At this we cannot be surprized, when we recollect the many steps which the formation of Classificatory Botany required. We must now notice some of the principal discoveries which tended to the formation of Systematic Descriptive Geology. Atlas et Description Minéralogique de la France, entrepris par ordre du Roi; par MM. Guettard et Monnet, Paris, 1780, pp. 212, with 31 maps. CHAPTER II. FORMATION OF SYSTEMATIC DESCRIPTIVE GEOLOGY. Sect. 1.-Discovery of the Order and Stratification of the Materials of the Earth. THAT the substances of which the earth is framed are not scattered THAT and mixed at random, but possess identity and continuity to a considerable extent, Lister was aware, when he proposed his map. But there is, in his suggestions, nothing relating to stratification; nor any order of position, still less of time, assigned to these materials. Woodward, however, appears to have been fully aware of the general law. of stratification. On collecting information from all parts, "the result was," he says, "that in time I was abundantly assured that the circumstances of these things in remoter countries were much the same with those of ours here: that the stone, and other terrestrial matter in France, Flanders, Holland, Spain, Italy, Germany, Denmark, and Sweden, was distinguished into strata or layers, as it is in England; that these strata were divided by parallel fissures; that there were enclosed in the stone and all the other denser kinds of terrestrial matter, great numbers of the shells, and other productions of the sea, in the same manner as in that of this island."" So remarkable a truth, thus collected from a copious collection of particulars by a patient induction, was an important step in the science. These general facts now began to be commonly recognized, and followed into detail. Stukely the antiquary (1724), remarked an important feature in the strata of England, that their escarpments, or steepest sides, are turned towards the west and north-west; and Strachey (1719), gave a stratigraphical description of certain coal-mines near Bath. Michell, appointed Woodwardian Professor at Cambridge 1 Natural History of the Earth, 1723. 2 Itinerarium Curiosum, 1724. 3 Phil. Trans. 1719, and Observations on Strata, &c. 1729. Fitton, Annals of Philosophy, N. S. vol. i. and ii. (1832, '3), p. 157. in 1762, described this stratified structure of the earth far more distinctly than his predecessors, and pointed out, as the consequence of it, that "the same kinds of earths, stones, and minerals, will appear at the surface of the earth in long parallel slips, parallel to the long ridges of mountains; and so, in fact, we find them." Michell (as appeared by papers of his which were examined after his death) had made himself acquainted with the series of English. strata which thus occur from Cambridge to York; that is, from the chalk to the coal. These relations of position required that geological maps, to complete the information they conveyed, should be accompanied by geological Sections, or imaginary representations of the order and mode of superpositions, as well as of the superficial extent of the strata, as in more recent times has usually been done. The strata, as we travel from the higher to the lower, come from under each other into view; and this out-cropping, basseting, or by whatever other term it is described, is an important feature in their description. It was further noticed that these relations of position were combined with other important facts, which irresistibly suggested the notion of a relation in time. This, indeed, was implied in all theories of the earth; but observations of the facts most require our notice. Steno is asserted by Humboldt to be the first who (in 1669) distinguished between rocks anterior to the existence of plants and animals upon the globe, containing therefore no organic remains; and rocks super-imposed on these, and full of such remains; "turbidi maris sedimenta sibi invicem imposita." Rouelle is stated by his pupil Desmarest, to have made some additional and important observations. "He saw," it is said, "that the shells which occur in rocks were not the same in all countries; that ccrtain species occur together, while others do not occur in the same beds; that there is a constant order in the arrangement of these shells, certain species lying in distinct bands.” Such divisions as these required to be marked by technical names. A distinction was made of l'ancienne terre and la nouvelle terre, to which Rouelle added a travaille intermédiaire. Rouelle died in 1770, having been known by lectures, not by books. Lehman, in 1756, claims for himself the credit of being the first to observe and describe correctly the structure of stratified countries; being ignorant, pro • Essai Géognastique. Phil. Trans. 1760. * Encyl. Méthod. Geogr. Phys. tom. i. p. 416, quoted by Fitton as above, p.159 bably, of the labors of Strachey in England. He divided mountains into three classes; primitive, which were formed with the world;those which resulted from a partial destruction of the primitive rocks; -and a third class resulting from local or universal deluges. In 1759, also, Arduine,' in his Memoirs on the mountains of Padua, Vicenza, and Verona, deduced, from original observations, the distinction of rocks into primary, secondary, and tertiary. 10 The relations of position and fossils were, from this period, inseparably connected with opinions concerning succession in time. Odoardi remarked, that the strata of the Sabapennine hills are unconformable to those of the Apennine, (as Strachey had observed, that the strata above the coal were unconformable to the coal;11) and his work contained a clear argument respecting the different ages of these two classes of hills. Fuchsel was, in 1762, aware of the distinctness of strata of different ages in Germany. Pallas and Saussure were guided by general views of the same kind in observing the countries which they visited: but, perhaps, the general circulation of such notions was most due to Werner. Sect. 2.-Systematic form given to Descriptive Geology.- Werner. WERNER expressed the general relations of the strata of the earth by means of classifications which, so far as general applicability is concerned, are extremely imperfect and arbitrary; he promulgated a theory which almost entirely neglected all the facts previously discovered respecting the grouping of fossils,-which was founded upon observations made in a very limited district of Germany,—and which was contradicted even by the facts of this district. Yet the acuteness of his discrimination in the subjects which he studied, the generality of the tenets he asserted, and the charm which he threw about his speculations, gave to Geology, or, as he termed it, Geognosy, a popularity and reputation which it had never before possessed. His system had asserted certain universal formations, which followed each other in a constant order;-granite the lowest,-then mica-slate and clay-slate ;-upon these primitive rocks, generally highly inclined, rest other transition strata ;-upon these, lie secondary ones, which being more nearly horizontal, are called flötz or flat. The term formation, Lyell, i. 70. 8 10 Ib. 74. VOL. II.-33. • Ib. 72. |