[16] Fitton, Annals of Philosophy, N. S. vol. i. and ii. (1832, ’3), p. 157.
[17] Phil. Trans. 1760.
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[18] 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”.
[18] Essai Géognostique.
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 certain 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.”[19]
[19] Encycl. Méthod. Geogr. Phys. tom. i. p. 416, as quoted by Fitton as [above], p. 159.
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, [513] probably, of the labors of Strachey in England. He divided mountains into three classes;[20] 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,[21] in his Memoirs on the mountains of Padua, Vicenza, and Verona, deduced, from original observations, the distinction of rocks into primary, secondary, and tertiary.
[20] Lyell, i. 70.
[21] Ib. 72.