Page:The Geologist, volume 5.djvu/111

Rh in the richer pastures. The number of mosses is exceedingly great. The beautiful Bryum dendroides and others abound in the moister spots of the Cave Dale. In fact, the botanical character of the vegetation hereabout is so peculiar to the three formations which are found as to form a geological map to the underlying rocks, coloured by nature herself! The limestone clothed with its short and beautiful carpet of green; the black shales of the Yoredale rocks covered by their stunted and brown vegetation; and the millstone-grit in the glowing summer-time quite purple with the flowers of the heather. And for land shells no other locality can compete with it. From the robust Helix aspersa to the diminutive Pupa numerous species intervene; some of them, such as Clausilia and Pupa, being more numerous in individuals than any other place that I have visited.

But to the geologist the rocks present treasures of fossils most beautifully preserved. I have found the Terebratula hastata retaining its purple colour-bands as beautifully as when alive in the carboniferous seas; and in some places every slab that is turned up is matted with Retepora and Fenestrella. Coming here from Manchester, along the new road from Chapel-en-le-Frith, the first place where we meet with the limestone is about a mile and a half distant from the town. This hill, Trecliff, is about six hundred feet in height, and the dip of the beds is about 25° in a direction N.N.E. It is in this hill that the "Blue John" mines are situated; and is the only locality in the country where this peculiar mineral is met with. It lies in "pipe-veins," having the same inclination as the rocks which the veins traverse. One of these veins lies in a sort of clayey stratum, and another seems to be imbedded in the nodule state in a mass of indurated débris. Besides these, the whole of the limestone masses are fractured and cracked, and, in addition to the pipes, the sides of the cavities are lined with the most perfect and beautiful sky-blue cubes of fluor, and the rhombic crystals of calcite. I remember scarcely anything with greater pleasure then an adventure in search of minerals a year or two ago, in one of these caverns, which was richly rewarded. Witherite, fluor-spar, varying in colour from transparency to rose, blue, violet and other colours, selenite, and occasionally phosphate of lead, are all found in the lead-mines of the neighbourhood. Some varieties of calcspar have the property of double refraction, like Iceland spar.

Nearly all the characteristic fossils of the carboniferous limestone abound, as may be seen by glancing at the names of the localities given in Professor Phillips's 'Geology of Yorkshire.' The richest localities for obtaining them is just below the "Blue John cavern," and in the gorge at the back of the town, which goes by the name of the Cave Dale. In geologizing along the side of Trecliff hill, one cannot but be struck with the various groups of fossils which the different beds present. The lower beds contain great quantities of Phillipsia—heads, carapaces, etc., being very frequently met with, and occasionally they are found whole. Just as we should have expected from knowing that the family of Trilobites died out with the moun-