The coal-measures repose conformably on a series of grit-beds, all more or less charged with oxide of iron, and measuring together about 500 feet in thickness. In some places a bed of limestone intervenes between the lowest bed and those above, but the general section, in descending order, is as follows:—

1. Coarse red grit-stone, called “The Miner's Farewell Rock.”

2. Light red sandstone, with layers of variegated marls, which, although partly indurated in the bed, fall to pieces by exposure to the air.

3. Fine-grained quartzose grit, much charged with iron in the middle beds, constituting the “Sandstone Mine Formation.” In this group there are two thin beds of coarse conglomerate, or pudding-stone.

It would be impossible for me to enter into any adequate description of this most important part of the Forest geology, without extending this article to an undue length. The following summary, therefore, must suffice, in the present instance; although I purpose describing the coalfield, which has special interest—geological as well as industrial—on another occasion.

If the ordnance geological sheet No. XLIII. S.E. be examined, with the horizontal sections Nos. 15 and 16, a very good notion of this coal-basin may be obtained, although not too much dependence is to be placed, practically, on the position of the lines marking the crop of the several veins. Indeed, to lay down the line of crop accurately, in many places where there are no workings, is impossible, from the thickness of the over-burden or soil: besides which, the theoretical lines invariably require to be shifted, from the occurrence of minor faults and local denudation.

The divisional line of the “Bottom Rocks” is not, however, to be placed at the point at which life first appears. This great series is naturally divided by differences of mineral conditions, by order of deposition, and in reality of age, in our own country, and in other countries both of Europe and America, and apparently also, as far as our present information goes, in Asia and Africa.

In Canada, below the equivalents of our Shropshire “Bottom Rocks” and of our lower Cambrian beds, as in the Highlands of Scotland, as we have already obtained, are still more ancient beds of sedimentary origin, which have become crystalline. In Bohemia, in Finland, and in Scandinavia we have these primeval gneissic lands below the lowermost Silurian deposits; but the geologists generally of other countries, except, the Canadian, have not yet made much progress in this investigation, and it is only in very few instances that the distinctions between the older and younger gneiss have been noticed; and so little regard as to geological age has been ordinarily paid in the case of granitic rocks, that, knowing as we do the very various periods at which some of those masses were erupted, or protruded through sedimentary strata, the mere knowledge of their existence is nearly or quite valueless as evidence.

The beds immediately below the Marlstone, which consist of laminated shales and clays often micaceous and sandy, were well exposed at the latter place during the formation of the reservoirs, and at Robinswood Hill, near Gloucester, and at Chipping Campden, on the north-eastern extremity of the county, a locality which deserves a special visit. In this part of the series, at the base of the Marlstone, a good deal of ironstone prevails, which, it is said, was in ancient times worked near Gloucester; it is of some thickness and of excellent quality at Campden. These beds are no where destitute of fossils, among which, at the last named place, we may especially notice the fine Ophioderma Gaveyi (one of the brittle-stars, some species of which are so frequent in our present seas) and a new species of Pentacrinites (P. robustus, Wright). Here, too, at the base of the Marlstone, Mr. Gavey found two previously undescribed forms of star-fish, the Uraster Qaveyi and the Tropidaster pectinatus, both of which were figured and described by the late lamented Professor Edward Forbes, in the 3rd Decade of the Geological Survey. With them he obtained an entire and beautiful large Cidaris Edwardsii (Wright), with the attached spines, a rarity in this condition in any formation, and especially in the Lias, where Echinoderms are very scarce; although we have met with specimens of some small species, with the spines attached, in the upper, middle, and lower Lias.

These fossil star-fish are often obtained grouped together, as living ones are now, with their short spines adhering to the rays. Indeed, they seem to have been more than usually abundant at this spot—at least, such is the case with the Tropidaster pectinatus. Two or three species of small Crustacea, chiefly belonging to the genus Astacus, were also procured there in the argillaceous nodules, irregularly distributed throughout the clay. The most interesting we have seen is one in our possession, nearly allied to the recent genus Æga, belonging to the order Isopoda, and which, like others of this group, was probably parasitic upon fish. There were also a great number and variety of marine shells in a remarkably good state of preservation, and these were equally abundant at Hewlett's Hill, some of them retaining the actual shell.

As the summer approaches, many of the readers of the Geologist will be preparing for their vacation-rambles; and should any think of visiting our Sister Isle—“Old Erin”—the following notes may be of service.

We started on a bright August morning of last year for the meeting of the British Association for the Advancement of Science, held in Dublin, and with the intention of travelling over as much country, breaking as many stones, gathering as many plants, and catching as many salmon as time and circumstances would permit. We were fortunate in our combination of naturalist and sportsman, but as these notes are intended solely for the naturalist, we leave our “salmon struggles” unrecorded—at least in the pages of the Geologist.

We travelled by Conway and Bangor to Holyhead, and as it was blowing a gale of wind when we arrived, we determined to wait until the sea was calmer, and, in the meanwhile, to visit the Cambrian rocks of Anglesea.

We never saw a more instructive example of contortion and twisting of rocks than is displayed at the South Stack Lighthouse, of which a good sketch is given in Sir R. Murchison's “Siluria.” It is indeed a rugged coast; and the terrible Bay of Caernarvon to the south has been the locale of more shipwrecks than any other in the British Isles. We visited the grand quarries of quartzite, worked on a gigantic scale for the great breakwater. Here, as the geologist approaches the quarry from Holyhead, is a greenstone-dyke traversing the quartzite with a singular vein of pink decomposing felspathic rock.