. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. ch. xxvlt.] WENLOCK FORMATION. 557 2. WenlocJc Formation. We next conic to tlie Wenlock formation, which has been divided (see Table, p. 550) into the Upper Wenlock, or Wenlock Limestone, and the Lower Wenlock, including, first, the Wenlock shale, and sec- ondly, the Woolhope limestone and Denbighshire grits. Upper Wenlock.— Wenlock Limestone.—This limestone, otherwise well known to collectors by the name of the Dudley limestone, forms a continuous ridge in Shropshir
. Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments. Geology. ch. xxvlt.] WENLOCK FORMATION. 557 2. WenlocJc Formation. We next conic to tlie Wenlock formation, which has been divided (see Table, p. 550) into the Upper Wenlock, or Wenlock Limestone, and the Lower Wenlock, including, first, the Wenlock shale, and sec- ondly, the Woolhope limestone and Denbighshire grits. Upper Wenlock.— Wenlock Limestone.—This limestone, otherwise well known to collectors by the name of the Dudley limestone, forms a continuous ridge in Shropshire, ranging for about twenty miles from to , about a mile distant from the nearly parallel escarpment of the Aymestry limestone. This ridgy prominence is due to the solidity of the rock, and to the softness of the shales above and below it. Near Wenlock it consists of thick masses of gray sub'crystallirie lime- stone, replete with corals and encrinites. It is essentially of a con- cretionary nature; and the concretions, termed " ball-stones " in Shrop- shire, are often enormous, even 80 feet in diameter. They are of pure carbonate of lime, the surrounding rock beino- more or less arc-ilia- ceous.* Sometimes in the Malvern Hills this limestone, according to Professor Phillips, is oolitic. Among the corals in which this formation is so rich, the " chain- coral," Holysites catenulai'ius, or Catenipora escharoides (fig. 631), may. EalysiUs catenularius, Linn, sp. Syn. Catenipora escha- roides, Goldf. Upper and Lower Silurian. 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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