. Elements of geology. Geology. 222 LYELL'S ELEMENTS OF GEOLOGY. Oolite Group Stonesfield Slate. broad band of country from Bradford, in Wilts, to Tetbury, in Gloucestershire. These calcareous slabs, or tile-stones, are sepa- rated from each other by thin seams of clay, which have been deposited upon them, and have taken their form, preserving the undulating ridges and furrows of the sand in such complete integrity, that the impressions of small footsteps, apparently of crabs, which walked over the soft wet sands, are still visible. In the same stone the claws of crabs, fragments of echini, br
. Elements of geology. Geology. 222 LYELL'S ELEMENTS OF GEOLOGY. Oolite Group Stonesfield Slate. broad band of country from Bradford, in Wilts, to Tetbury, in Gloucestershire. These calcareous slabs, or tile-stones, are sepa- rated from each other by thin seams of clay, which have been deposited upon them, and have taken their form, preserving the undulating ridges and furrows of the sand in such complete integrity, that the impressions of small footsteps, apparently of crabs, which walked over the soft wet sands, are still visible. In the same stone the claws of crabs, fragments of echini, broken shells, pieces of drift wood, and other signs of a neighbouring beach, are observed. The slate of Stonesfield has lately been shown by Mr. Lons- dale to lie at the base of the Inferior Oolite. It is an oolitic shelly limestone, only six feet thick, but very rich in organic remains. It contains some pebbles of a rock very similar to itself, and with them the fossil remains of belemnites, trigonise, and other marine shells. Besides fragments of wood. Fig. 218. which occur in all parts of the oolitic group, there are many impressions of ferns, cycadeoe, and other ter- restrial plants. Several insects also, and among the rest, the wing-covers of beetles, are perfectly pre- served, (see Fig. 218.) some of them approaching nearly to the genus Buprestis.* The remains, also, of many genera of reptiles, such as Plesiosaurus, Crocodile, and Pterodactyl, have been discovered in the same limestone; and, what is still more remark- able, the jaws of at least two species of mammiferous quadrupeds, allied to the Didelphys, or opossum. These fossils afford the only example yet known of terrestrial mammalia in rocks of a date anterior to the Eocene period. This exception is the more deserving of notice, because even no cetacea have as yet been observed in any secondary strata, although certain bones, from the great oolite of Enstone, near Woodstock, in Oxfordshire, have been cited, on the a
Size: 924px × 2706px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlyellcharlessir17, bookcentury1800, booksubjectgeology
