The entire concealment of the upper slates (A3 in the diagram), and the partial concealment of the middle slates (A2), on the north sides of the axis of movement, is a circumstance of much importance in reasoning on the physical agencies which have been anciently at work on the district of Cumbrian slates. This deficiency of the upper fossiliferous beds is probably due to the wasting and destruction of them on that side of the axis, during the time which elapsed between the elevation of the central area and the formation around it of the next series of strata on the new bed and borders of the sea. While rising above the sea level in a shaken and fragmentary state, the slate rocks would be exposed to rapid disintegration and waste, first by the sea-breakers, and afterwards by the atmospheric agencies, and especially the upper bed, which formed the surface, would be wasted. The ordinary action of the sea on its now stationary coasts, and on solid rocks, is very powerful, but may be regarded as almost of no moment if compared to that violent force which accompanies earthquake movements, and it is difficult to overrate its effects on land rising under a large area by convulsive throes in shattered and broken masses.

To the successive operation of disturbing movements on the crust of the earth, and of the littoral action of the sea, excited to violence by the change of level and displacement of liquid, modern geology ascribes the most important surface changes of the globe, its rugged glens and ridgy mountains; while the effect of land streams and atmospheric influences upon these features has been to soften and fill up the chasms, and moderate the precipitous aspect of the mountains. Such effects are the natural, and indeed necessary, consequences following upon the conditions which have been proved. But this reasoning is further confirmed by the nature of the next class of deposited strata, and by the circumstances in which they are found; for these show incontestibly, as facts, that the surface of the slaty rocks of all ages was thus formed into valleys, and that their disrupted ma

terials were transported by water, and re-arranged along the borders of the sea.

OLD RED STRATA.

The old red sandstone appears, round the district of the Lakes, resting on the more ancient slates, but only in a few localities, and under an aspect very different from that which it wears in Caithness, along the Grampians, or on the border of Wales. There it forms immense areas of country, consists of innumerable beds amounting to several thousand feet in thickness, and contains most singular remains of fishes. Here it is confined to a few valleys, is of only a few tens or a few hundreds of feet thick, and has yielded no 'relics of life; yet, in a general sense, it is, by composition and history, allied to the larger and more prolific deposits alluded to.

The valley of the Lune above Kirkby-Lonsdale exhibits the best series of these red rocks, but they occupy a larger area, have greater thickness, and rise to higher ground, at the lower end of Ulleswater. The Lune river crosses, in its picturesque course, within two miles of Kirkby-Lonsdale, the upper part of the slate rocks with fossils, at Beck Foot; then divides cliffs of the old red series, which consist of red clay, with some concretionary subcalcareous masses (like the more definite rock called "Cornstone" in Herefordshire), surmounted by red conglomerates full of pebbles, derived from the slate regions adjacent.

The mountain limestone follows, but a clear and perfect junction of this rock with the old red is wanting here. The nearest approach to a perfect junction is in Casterton woods, by the pretty waterfall.

Near Ulleswater, the limestone is separated from the slate by a narrow band of laminated arenaceous red marls without conglomerates; at Dacre, near Pooley Bridge, and at Butterswick, near Shap Abbey, the conglomerate beds may be seen between the limestone and

the slates. Mell Fell and Dunmallet are the only conspicuous hills of red conglomerate in the whole Lake district. The former rises to a height of 1000 feet above the sea.

In the valley of the Mint near Kendal, in the Rother near Sedbergh, in Barbon Beck between the chapel and the bridge, the old red conglomerate may be seen under peculiar circumstances, and to great advantage.

From a careful study of all these localities, there results the conclusion, that the red deposits, taken generally, occupy ancient valleys, and the sides of ancient valleys, which were excavated in the slaty rocks previous to the old red period. Among the fragments which fill the conglomerates, we find rolled masses of the neighbouring slaty rocks, pieces of vein quartz, and specimens of the micaceous iron ore which lies in veins in the slaty country. From these facts it is evident, that, previously to the junction of the conglomerates, the slate rocks had been indurated, displaced, fissured, excavated into valleys, and impregnated with mineral veins! What a lesson is here for the inquiring geologist, what a reproof for the sceptic who doubts the antiquity of the earth, and the immense range of its physical history before the era of the creation of man.

By observing the elevation along the boundary of the Lake district, to which we find the conglomerates reach, we obtain a rude incasure of the ancient limit of the sea, round the newly risen islands of the slate. We say limit, not level; for, in fact, the variation of level must be ascribed to the land, and the standard of level awarded to the sea. There is no trace of the old red visible on the western side of the Lake district; and this may be, because the ancient sea limit, on that side, had soon after sunk below the modern sea-level, and become covered up by deposits later than the old red rocks. On that side, all the immediately succeeding deposits occupy, in general, lower levels than on the eastern side; so that a relative subsidence of the western lake region may be believed to have continued through the carboni

ferous period-a supposition which agrees with the local richness of the coal-beds there; for this fact is in harmony with subsidence of a sea-coast.

We may gather, from the condition of the pebbles in the conglomerate, that the littoral action of the sea, during the old red period, was violent; that the coarse detritus of the shores was chiefly collected in bays and hollows, where comparative tranquillity reigned; that it is only the edge of the old red which is now shown to us, while the deeper beds of the ocean, which received most of the sandy and muddy deposits, are now hid from our view by the later deposits of limestone, gritstone, and coal, which mark the next great portion of geological time.

CALCAREO-CARBONIFEROUS SYSTEM OF STRATA.

Mountain Limestone. - Under this title, geologists include a thick series of deposits, in which limestone abounds, and sometimes predominates, or even constitutes, alone, nearly the whole of the mass. This happens in Flintshire, and rather generally in South Wales and Somersetshire. In Derbyshire, the thick limestone is surmounted by shale, and then by the millstone grit series; in Yorkshire, the same limestone is surmounted by shale, gritstone, and coal; and this by the millstone grit series.

The thick LOWER LIMESTONE is seen abundantly round the Lake district; as near Ulverston, Cartmel, Witherslack, Kendal, Milnthorpe, Kirkby-Lonsdale, Sedbergh, Orton, Shap, Lowther, Greystock, Caldbeck, Tor. penhow, Cockermouth, Cleator, and Egremont. Everywhere it forms bold hills; often presenting rough precipices toward the Lake mountains, dignified by the title of "Scars, as Whitbarrow Scar, Underbarrow Scar; or 66 Knots," as Farlton Knot; or simply termed "Fells," like other less remarkable hills. It rests upon the upper silurian rocks, near Kendal; upon the middle slates, near Hesket Newmarket; upon the lowest slates,

near Egremont. Thus it is "unconformable" to those rocks, and the cause of this is, the great disturbance of the sea-bed which followed upon the completion of the slaty series of strata. Generally speaking, this limestone appears, by the regularity of its beds and the purity of its calcareous composition, to have been deposited beyond the influence of the littoral agitation of the sea. In some places (as near Ingleton, in Yorkshire) its lowest beds contain abundance of fragments of the subjacent slaty rocks: near Lowther, beds similarly placed, contain quartz pebbles: and as we proceed to the north, a series of sandstones, shales, and coal, is interpolated among the limestones. This is seen chiefly on the eastern side of the Vale of Eden, under the great escarpment of Cross Fell. The geologist should remark, beneath the limestone range of Orton Scars, a lower plateau, in which red sandstone prevails; for this appears to be associated with fossiliferous limestones, locally of a red colour, the whole suggesting the idea of a temporary return, during the calcareous period, of the actions which had prevailed during the old red sandstone era. -(See Geology of Yorkshire, vol. ii.)

The colours and textures of the limestone render it suitable for marble. The most curious, perhaps, is the clouded marble of Beetham Fell. Some beds are full of shells, others of corals, others of crinoids; and nearly all disclose to the microscope multitudes of minutely organized animal tissues. A great part of the mass is distinctly composed of organic reliquiæ; the hard parts of invertebrate animals (with a few fish-teeth and finbones); and it is, perhaps, not an extravagant conjecture, to regard it as of the nature of an ancient shell, coral, and crinoid reef, encircling the insulated lake mountains, analogous to the coral reefs which prevail, in the modern period, around the islands of tropical seas.-Professor Sedgwick advances this opinion in his Letters on the Geology of the Lake district. The crinoidal stems are usually disjointed, and appear to have been displaced by currents, and then aggregated into beds. This great