micaceous stone sometimes occurs in the upper parts, having the appearance of silver: hence the name of "Silver Stone" given to a spot near the Hawthorns, where it is found. The surface which the carboniferous limestone exposes is also represented in the map. The Forest coal-field is surrounded by this formation, with the exception of the line of fault between Lydney Park and Danby Lodge, a distance of four miles. 66 66 66 66 The principal iron-mine train of the district divides into a lower or more crystalline, and an upper or more argillaceous and sandy stratum. Mr. Mushet thus describes this important metallic vein :-"The iron ores "of the Forest of Dean, which have become intimately known to me, are found, like the ores of "Cumberland and Lancashire, in churns or caverns "formed in the upper beds of the mountain or carboni"ferous limestone. The leaner ores contain a great deal " of calcareous matter in the shape of common limestone or spar, which reduces the percentage in the ore as "low as between 15 and 25 per cent., and it seldom exceeds 25, except when mixed with fragments of what "is called brush ore, which, when in quantity, raises the "percentage to 40 or 45. Brush ore is a hydrate with protoxide of iron, and frequently, if not much mixed "with calcareous earth, contains from 60 to 65 per cent. "of iron. These ores are found in chambers, the walls of "which are exceedingly hard limestone, crystallized in "rhombs. This limestone is called the 'crease,' and is frequently found enveloped and covered with the iron ore. "The miner has to cut his way through this crystallized "limestone from chamber to chamber, a distance of from "20 to 100 yards, before he reaches the next of these deposits, which are sometimes found to contain 3,000 66 or 4,000 tons of ore. The principal part of the ore is "then dug easily, somewhat like gravel; but the sides of "the chambers are often covered with the stony ore "before described, which requires gunpowder to detach "it from the rock." These various ores were found by the same excellent authority to yield iron in the following proportions: 66 66 The inhabitants of the Forest consider the ores obtained on the east side superior to those on the west. They likewise suppose, but probably without foundation, that the ore will be found to deteriorate in proportion as the workings descend. Red and yellow ochre of superior quality occur in the iron veins, and have at various times been in considerable request. They are now used in the neighbourhood for marking sheep, and tinting whitewash. Reverting to the limestone beds of the district, the lower veins are locally called "blue stone," the middle "red stone," and the top vein the "white head," which is largely used as a flux in the smelting furnaces. The researches of Mr. R. Gibbs, of Mitcheldean, have enabled him to furnish me with the following list of fossils discovered by himself in the Forest limestone formation :— Zoophyta. Syringopora reticulata, Turbinolia fungites, Lithostrotion irregulare. Echinodermata.-Actinoerinus aculeatus, et lævissimus, Platyerinus lævis et rugosus. Mollusca Dimyaria.-Pallastra complanata. Brachiopoda.-Terebratula hastata. Spirifer glaber, et rhomboideus. Chonetes cornoides, et papilionacea. Productus cora, et longispinus, et martini, et pustu- Lamellibranchiata.-Monomyaria. Pisces. Aviculopecten fallax. Dimyaria. Psammobia complanata. Ctenacanthus tenuistriatus. Cladodus conicus. Psammodus porosus, et rugosus. The millstone grit beds immediately succeed those of the carboniferous limestone just described, forming a similar belt round the Forest, and disappearing with it on the Blakeney side of the basin. Its chief interest consists in the circumstance that it has been employed from very early times as a material for building; for though it contains a vein of iron ore, little has been done in mining it. Most of the old buildings adjoining the parts where this grit crops out are formed of it, as several of the ancient neighbouring churches show, and likewise the oldest lodges in the Forest; now, however, this kind of stone is seldom used except for boundary walls, and such kind of rough work. The rest of the outer circle of high land, on whose summit the observer has been supposed to be standing, and which so definitely marks the Forest coal-field, comprises the lower coal measures, containing the lower and upper Trenchard veins, the Coleford High Delf, with the Whittington and Nag's Head seams, which together give about eleven feet of coal. Of these the Coleford High Delf, averaging a thickness of upwards of five feet, and extending over an area of 16,000 acres, is undoubtedly the chief, although in some places it has suffered from various disturbances, the principal of which occur in the neighbourhood of Coleford, extending in a line from Worcester Lodge to Berry Hill, and is marked on the surface by a succession of pools, named Howler's Well, Leech Pool, Crabtree Pool, Hooper's Pool, and Hall's Pool. Mr. Buddle describes the width as varying from 170 to 340 yards in the most defined part, called by the colliers the "Horse," and the dislocations adjoining, the "Lows." "It is not," he remarks, "what geologists term a fault, as there is no accompanying dislocation of the adjoining strata. In its underground character it is similar to those washes or aqueous deposits in many coal districts, but it differs "from them in not being under the bed of any river, 66 nor in the bottom of a valley, nor does it show itself at "the surface." And he adds, "On considering the " various phænomena presented by this fault, and the " seam of coal on each side of it, we may infer that it occupies the site of a lake which existed at the period "of the deposition of the High Delf seam, and that 66 66 66 66 |