limestone series is from 500 to 1000 feet thick in the Yorkshire Dales. It may be well studied in the vicinity of Ingleton, Settle, and Kirkby-Lonsdale. Caverns and fantastically excavated rocks mark the range of this limestone in various parts; especially under Ingleborough and Whernside. The river scenery of Kirkby-Lonsdale and Caldbeck, and the sea-coast of Conishead, near Ulverston, are much enriched by its romantic cliffs and terraces. Mineral veins are not so plentiful in the mountain limestone round the lakes, as in other tracts of the same rock. Sulphuret of lead was found in it under Ingleborough, carbonate of copper near Ulverston, and carbonate of zinc (calamine) in Bolland Forest. But iron is the only valuable metal now obtained from this rock, in the district of the lakes. It occurs in the state of a rich hæmatite (perixode of iron), near Dalton, in Furness, and at Cleator, near Egremont. The vein of this valuable substance, near Dalston, fills a wide fissure in the limestone, and has long yielded to the iron-masters of South Wales the means of enriching the produce from their furnaces, by admixture with the native poorer clay ironstones. Organic remains are extremely numerons in the great limestone rocks of Kendal, Kirkby-Lonsdale, Orton Caldbeck, Cockermouth, and Egremont. They consist of corals, in various states of preservation; columns and smaller parts of encrinites; two species of echinida; several hundred species of bivalve, univalve, and concamerated shells, fish-teeth and fin-bones. The reader will find a nearly complete account, with figures of these organic remains, in Phillips's Geology of Yorkshire, vol. ii. The UPPER LIMESTONE series is conspicuous on the middle slopes of Ingleborough, Whernside, and Wildboar Fell, but forms only a secondary feature in the calcareous belt of the Lake country on the north, ranging from near Lowther, on the north side of Hesket Newmarket, by Bolton, to near Cockermouth. It also appears in Low Furness, south-east of Dalton, and south of Kirkby-Lonsdale, about Huttonroof, and Whittington. It yields fine marble, especially in Garsdale and Dentdale, of two sorts: one, from the lowest beds, black; the other, from the highest, gray, and full of crinoidal columns, each resembling a variety of the Derbyshire marbles. Good flagstone occurs in this series, at Huttonroof, near Kirkby-Lonsdale, and poor beds of coal, in the same vicinity, at Sleagill, near Orton, and near Hesket Newmarket. The organic remains are extremely numerous, but generally similar to those mentioned in the lower limestone. One of the beds of this series, at Alston Moor, is called "Cockle-shell Lime," from the plenty of bivalve shells (producta) in it. The Millstone Grit Group is about 800 feet thick in the Yorkshire mountains, and consists of three distinct coarse sandstones or quartzose conglomerates, with several flaggy sandstones, shales, and coal-beds; but it is only feebly traceable parallel to the northern border of the Lake country; and, indeed, is hardly separable from the beds of the division just noticed. Organic remains (animal), similar to those of the limestone, occur in some of the shales, and others, like those of the coal (plants), are met with in some of the sandstones. The group is altogether of an intermediate character between the limestone and the coal formation. The Coal Formation, which is the uppermost part of the calcareo-carboniferous system, contains no true limestone-beds; but consists of sandstones and shales of various kinds, enclosing several regular beds of coal, and some bands of ironstone nodules. This valuable series of deposits merely fringes the sea-coast, from St. Bees' Head, near Whitehaven, to Maryport; and the coal is sought with such avidity, that the works are now extended far beneath the sea, both at Whitehaven and at Workington. The westward dip of the coal favours this bold operation; but faults, and local changes of dip occur, which render the enterprise not a little dan gerous, as well as difficult. A serious accident from this cause happened in 1837. The fossils of the coal tract are chiefly plants of the sorts usually classed as Calamites, Stigmariæ, Sigillariæ, Lepidodendron, and Ferns. Some of the sandstones of the millstone grit group, and others of the upper limestone series, contain stems of plants, very rarely leaves of ferns; but the extreme abundance of the remains of plants is a positive character of the coal deposits. SECOND GREAT INTERVAL OF DISTURBANCE. The accumulation of coal, which was favoured by a general and continual descent of the shore and bed of the sea, ceased, when a contrary movement, of a violent character and very extensive sphere of operation, took place. The movement thus described, affected, with great fractures and enormous displacements, the area of the coal and mountain limestone and more anciently solidified strata, in the whole of the British Isles, and over large parts of Europe and America. Its effects in and around the Lake district, may be summed in the following abstract :— 1. The main geographical features of the district; its great mountain ridges, and great vale depressions, received from this movement their last decisive impress. The insulated character of the Lake mountains, which was evident at the close of the first great disturbance, was now modified on the eastern side, by the elevation of a long and wide range of high ground, extending from what is now the vale of the Tyne, to the sources of the Aire and the Ribble; and the sea which had flowed without interruption around, was bounded by the lofty isthmus of Howgill Fell and Wildboar Fell; and rejected, far to the south, by a general rising on the whole of the south-eastern margin of the district. 2. The relative elevations of land in and around the Lake district, which we behold at this day, were acquired at that time; and their absolute elevation above the sea, may be stated, with much probability, at about 500 feet less than it is at present. The evidence for this will immediately appear. NEW RED SANDSTONE. If a line be drawn from near Lowes Water, across the Bay of Morecambe, and continued across Furness, by the town of Dalton, and afterwards by Bootle, Ravenglass, and Egremont, to St. Bees' Head, it will mark the ancient sea-shore after the second great upward movement of the Lake rocks. On the south and west of this line, the new red sandstone is found deposited in nearly horizontal strata, against the ends of vertical, contorted, or variously inclined Paleozoic rocks, already described. From St. Bees the line is interrupted for a space by the modern sea, but is recovered near Maryport, and thence sweeps continuously round the Lake region, south of Allonby and Wigton, west of Penrith and Appleby, to Kirkby Stephen. From this point, as from a deep bay, the line of ancient coast returns by Brough and Dufton, beneath the range of the Cross Fell mountains, to cross the Irthing and the Liddel, and extend long arms into the vales of Annan and Dumfries, and, finally open into Solway Firth and the Irish Sea. Along the line thus defined, the sea washed cliffs and slopes of slate and granite, from near Bootle to near Egremont; coal strata from St. Bees to Maryport; easy slopes of mountain limestone, and its associated grits and shales, as far as Kirkby Stephen; and steep cliffs of the same rocks, from this point far to the northward-along all this much varied shore, and in the adjoining deeps and shallows, new and extensive deposits happened, which (with only the exception of one mass of beds) are not derived from, nor even characterized by, the mineral aggregates, which the waters touched and wasted. They generally consist of red sandstones and red marls (occasionally varied by lighter greenish tints, in which the peroxide of iron plays a very remarkable part). Iron exists, and often abundantly, in mountain limestone and coal formations, but generally as protoxide, or carbonate of the protoxide. Such is also the condition of the iron in almost the whole slate series, while in the old red sandstone the peroxide prevails. Thus we have the following mineral series from above: New Red Peroxides. Slaty Protoxides. The red deposits are by far too extensively spread in Europe, and even beyond its limits; and their characters are too constant and general to allow of being understood as the effect of local influences. We must believe that the lake mountains were surrounded by the new red sandstones, through the agency of sea-currents, which derived their mineral admixtures from the waste of distant shores; and gathered these admixtures in such abundance, as to fill all the oceanic basins of that geological age, in Europe, with the same, or a very similar, series of depositions. There To this conclusion there is one exception. is one set of beds associated with the red series, and forming sometimes its lowest visible part, which is only locally distributed, and is evidently of local origin. This is a series of beds, often approaching to or constituting limestone, but generally full of fragments, either angular or rolled, derived from the rocks of the adjacent shores, especially from the mountain limestone rocks, which formed in fact, a large portion thereof. To this the name of calcareo-magnesian conglomerate is applicable. It has been regarded as the equivalent of the magnesian limestone of Yorkshire and Derbyshire. It may be studied near Whitehaven, and to great advantage at Stenkrith Bridge, near Kirkby Stephen. |