. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. Ammonites margaritatus, Montf. Syn. A jStokesii, Sow. Middle Lias. Among the Crinoids or Stone-lilies of the Lias, the Pentacrinites are conspicuous. (See fig. 449.) Of Ophioderma Egertoni (fig. 450), referable to the Ophiuridce of Muller, perfect specimens have been met with in the Middle Lias beds of Dorset and Yorkshire. Allusion has already been made, p. 416, to numerous zones in the Lias characterized by distinct Ammonites. Two of these occur near the base of th
. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. Ammonites margaritatus, Montf. Syn. A jStokesii, Sow. Middle Lias. Among the Crinoids or Stone-lilies of the Lias, the Pentacrinites are conspicuous. (See fig. 449.) Of Ophioderma Egertoni (fig. 450), referable to the Ophiuridce of Muller, perfect specimens have been met with in the Middle Lias beds of Dorset and Yorkshire. Allusion has already been made, p. 416, to numerous zones in the Lias characterized by distinct Ammonites. Two of these occur near the base of the Lower Lias, having a united thickness, varying from 40 to 80 feet. The upper and larger of these is characterized, espe- cially in the southwest of England, by Ammonites Bucklandi, and the lower by Ammonites Planorhis (figs. 447, 448).* Fig. Ammonites Buc7clandi, Sow. " bisulcatus, Brug. I diam. of original. a. Side view. &. Front view, showing month and bisnlcated keel. Characteristic of the lower part of the Lias of England and the Continent. Fig. 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. New York, D. Appleton and co.
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectgeology, bookyear1868
