. Elements of geology. Geology. a. Terehratula lyra. \ Upper Green-sand. Pecten 5 costatus. b. Same, seen in profile. ) France. Upper and lower green-sand. Fig. Hamites spiniger (Fitton,) near Folkstone.* The fossils of the green-sand are marine, and some of them, like the Pecten qiiinquecostatus, (Fig. 166.) range through all the members of the series. Several forms of cephalopoda, such as the Hamite, (Fig. 167.) Scaphite, and others distinguish the Green-sand formation in England from the White Chalk. Origin of the Green-sand formation.—Unlike the white chalk, this deposit consists of
. Elements of geology. Geology. a. Terehratula lyra. \ Upper Green-sand. Pecten 5 costatus. b. Same, seen in profile. ) France. Upper and lower green-sand. Fig. Hamites spiniger (Fitton,) near Folkstone.* The fossils of the green-sand are marine, and some of them, like the Pecten qiiinquecostatus, (Fig. 166.) range through all the members of the series. Several forms of cephalopoda, such as the Hamite, (Fig. 167.) Scaphite, and others distinguish the Green-sand formation in England from the White Chalk. Origin of the Green-sand formation.—Unlike the white chalk, this deposit consists of a succession of ordinary beds of sand, clay, marl, and impure limestone, the materials of which might result from the wearing down of pre-existing rocks. The nature of these derivative rocks we learn, from finding in the green-sand pebbles of quartz, quartzose sandstone, jasper, and flinty slate, together with grains of chlorite and But we naturally inquire, how it could happen that, throughout a large submarine area, there should be formed, first, a set of mechani- cal strata, such as the green-sand, and then over the same space a pure zoophytic and shelly limestone, such as the white chalk. Certain causes, which during the first period gave rise to depo- * Fitton, Geol. Trans., Second Series, vol. iv. pi. 12. t Ibid. p. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Lyell, Charles, Sir, 1797-1875; Gibbes, Lewis Reeve, 1810-1894, former owner. DSI; Merrill, George P. (George Perkins), 1854-1929, former owner. DSI. Philadelphia : James Kay, Jun. and Brother ; Pittsburgh : C. H. Kay & Co.
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Keywords: ., bookauthorlyellcharlessir17, bookcentury1800, booksubjectgeology
