died on the spot, and that what is now considerably elevated must have been once the bottom of a fresh water lake, which was twice within the bosom of freshwater, and in the interval covered by salt water. The freshwater formation of England has none of the beds of gypsum, found in the French strata, replete with bones of extinct quadrupeds. The lower freshwater formation has been observed at Hordwell Cliff, Hampshire.-Geol. Trans. 2d series, Vols. I. & II.

§ V. UPPER MARINE FORMATION.

1. This is observed in three districts; that of Suffolk, where the deposit on the London clay appears as a sand or gravel enclosing shells of peculiar characters. This whole mass is called Crag.

2. The sandy beds of Bagshot, and the neighbouring heaths.

3. The marine stratum, alternating with those of freshwater in the Isle of Wight, which consists of a shelly marl. Many of the fossils belonging to the beds of the Suffolk crag, agree with those in the upper marine formation of the Paris basin. A few shells only, which may be placed among those which are supposed to be lost, or among those which are the inhabitants of the distant seas, are discoverable here; but the greater number do not seem to differ specifically from the recent shells of neighbouring

seas.

A peculiar terebratula has been described, as well as many other curious testaceous remains. This bed at Walton Nase, Essex, and on the cliffs on both sides of Harwich, is 30 feet thick. It furnishes a good soil. The gray weathers or Druid

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stones of Stonehenge belong to the siliceous sandstone of the Bagshot heath formation.

§ VI. SUMMARY RECAPITULATION.

Guided by the inductive spirit of English geology, we have traced in the preceding chapters, the successive ranges of mineral strata from their primitive bases up to the surface soil. The Alps, Scotland, and other mountainous regions, afford better fields for the study of granite, gneiss, and mica-slate; but in no country can the coal-measures, and the supermedial strata be examined with so much advantage as in England, in consequence chiefly of the numerous sections which have been accurately made, and faithfully recorded, without regard to any hypothesis.

1. We have seen the coal-measures, or their equivalent beds, surmounted by the conglomerate limestone, called the newer magnesian, to distinguish it from the magnesian lime occasionally subordinate to the carboniferous limestone. This conglomerate is the first floetz limestone of continental writers. It is covered by the new red sandstone, or red marl rocks of England. Between the first flatz limestone and coal-measures of the Germans, their first flotz sandstone lies, called rothe todte liegende, or red dead layer, because it is barren of the metallic veins found in the lower beds.

2. Next comes the oolitic series of rocks, the limestone beds of which are generally characterised by the spherical form of their calcareous particles, hence called roestone, peastone, or eggstone, according to their size. Immediately on the red

ground, the lias rests, being a structure of argillaceous limestone beds, in thin slabs, separated by seams of clay. Over this formation, we have the lower system of oolites, including fuller's earth, and bastard freestone, which reposes on calcareous sand. We now come to the great oolite, the Forest marble, and the Stonesfield slate, which are surmounted by the cornbrash. It is in this valuable oolite, that the sphericity of the calcareous concretions becomes most remarkable. These beds are covered by the Oxford clay, which is roofed with the coral rag, a mixed formation of calcareous and siliceous beds. Next in the order of superposition appears the upper division of the oolitic series, distinguishable into its three strata of Kimmeridge clay, Portland oolite, and Purbeck argillaceous limestone. This very important series, the oolitic strata, seems to be very rare in Scotland, and to exist but imperfectly in two or three patches of lias in Ireland.

3, 4. In ascending from the oolitic series, we find beds of iron sand, clay, green sand, and chalk-marl, leading to the great chalk formation; strata to which I am not aware that Scotland possesses any analogues, except in two or three spots in the Hebrides and Sutherland. 5. The tertiary class of strata which repose upon the chalk, have been examined under the most favourable circumstances, and with commensurate skill in the Paris basin, by MM. Cuvier and Brogniart. A brief abstract of their elaborate memoir, will conclude our view of the stratiform masonry of our globe.

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§ VII. ALTERNATE FRESH AND SALT WATER BEDS. OF THE PARIS BASIN.-The ground in which this capital lies, with the surrounding territory to a very considerable distance, presents a geological formation very remarkable for the diversity of its constituent strata, and the extraordinary relics of ancient organised beings which it has revealed. Its principal mass consists of myriads of marine shells, placed in regular alternate order with fresh water shells. Certain spaces are replete with skeletons of animals, unknown to the living world, even in generic affinity; while other bones, belonging to very considerable species, whose congeners are now found only in very distant countries, lie scattered about in the more superficial strata. In the forms of the capes and the directions of the principal hills, a marked character is impressed, of a great irruption of water having come from the south-east. We may hence infer that few localities are more capable of giving us information concerning the latest revolutions which completed the fabric of our globe.

The basin of the Seine is widely separated from that of the Loire, by a vast elevated plain, the greatest portion of which is commonly called the Beauce. The declivities of this extensive tableland are in general very steep, and all its naked escarpments, the sides of its valleys, and the wells which perforate the upper grounds, show that the physical constitution of the surface is the same throughout; consisting of a prodigious mass of fine sand, which covers the whole district, and invests

all the other strata of the slopes and lower plains. The materials which compose the basin of Paris, seem to have been deposited in a vast concavity, a species of gulf, lined throughout with chalk. Enumeration of the different kinds of strata or formations, which constitute the geological district of Paris.