covery of the silicified trunk of a tree often leads the miner to follow it into the rock, and thereby detect valuable cupriferous masses. The copper ore sometimes interlaces with all the fibres of the wood; at other times is continuous through a mass of leaves, matted in sand or marl. The copper beds only extend three or four hundred versts at farthest from the Ural, and Sir R. Murchison thinks that the ore may have been derived from mineral springs, formed during the igneous action to which that region was in ancient times exposed, the metal being collected into masses by the chemical action arising in the decay of the wood.

Not less interesting are the masses of salt found in the southern extension of the same formation in the great steppes near the Caspian. The most important is at Illetzkaya-Zastchita, which, with its groves of trees, its fort, and well-arranged buildings, beside some mounds of gypsum, forms an agreeable and unexpected green oasis in the barren wilderness south of Orenburg. Amid the marl and gypsum, a mass of pure rock salt occurs, which has been traced throughout a space of more than a mile in diameter. In one place, the surface is exposed, and the salt wrought as an open quarry; large square blocks being first cut out vertically by the axe, and then broken from their base by a smart blow with a kind of battering ram. one side the salt forms a perpendicular glassy cliff, about sixty feet high, overhanging a pool of saline water, which has undermined its base.

Another curiosity of this remote spot is a freezing cave, found in the south side of one of the gypsum hillocks. When Sir R. Murchison visited it, the external thermometer in the shade stood at 90°, but no sooner was the frail door closing the cavern opened, than a stream of cold air rushed out, causing the travellers to withdraw from its influence.

On entering it at three or four paces from the door, on which shone the glaring sun, we were surrounded by the half-frozen quass and provisions of the natives, and a little further on, the chasm (bending slightly) opened into a natural vault, about twelve to fifteen feet high, ten or twelve paces long, by seven or eight in width. This cavern seemed to ramify by smaller fissures into the body of the little impending mount of gypsum and marl. The roof of the cavern was hung with undripping solid icicles, and the floor might be called a stalagmite of ice and frozen earth. As we had no expectation of meeting with such a phenomenon, we had left our thermometers at Orenburg, and could not, therefore, observe the exact degree of cold below the freezing point. The proofs of intense cold around us were, however, abundantly decisive for our general purpose, and we were

glad to escape in a few minutes from this ice-bound prison, so long had our frames been accustomed to a powerful heat.'

According to the unanimoys testimony of the natives, the cold is greatest when the external heat is most intense, whilst in winter the cave is comparatively warm. This latter circumstance has been doubted, but we think without reason. Of the various explanations of the phenomenon given in the work before us, the one nearest the truth seems that of Pictet, except in so far as it supposes the cold to be partly produced by evaporation. We have no doubt that it is entirely the result of the disposition of the fissures in the hill, and the currents of air in them produced by changes in the temperature of the external atmosphere; and we imagine that it would not be difficult to form an artificial ice-house of similar character.

Next in ascending order are the Jurassic or Oolitic deposits, which, though resting almost horizontally on the more ancient strata, are yet believed by our authors to be separated from them by a wide interval of time, during which the triassic system-or new red and keuper sandstones—with the lias and lower oolite of Western Europe was deposited. Of the latter, or Trias, scarce a trace exists in Russia, except in a few fossils from Mount Bogdo. The general character of the Jurassic formations is that of low masses of slightly coherent, darkcoloured, pyritous shale or clay, with sands and concretions, and containing ammonites and belemnites. This system is seen to the south of Orenburg, on the Volga near Saratof, and on the same river higher up at Simbirsk, whence it stretches west in a broad line to beyond Vladimir. The Jura beds, filling a basin of the carboniferous rocks, also form the substratum on which the ancient city of Moscow is built. From Jurieretz, on the Volga, another mass extends north-east, rapidly increasing in breadth, through the great marshes that divide the tributaries of the Dwina from the streams that flow south to the Caspian. A still larger mass, even thus far north, retaining its characteristic fossils, fills the basin of the Petchora, and, covered by the marshy forests and bleak tundras, extends from the Timan mountains to the Arctic Sea.

If a line be drawn from Memel on the Baltic, to Voroneje on the Don, thence north to Jelatma on the Oka, again east to Simbirsk on the Volga, and from this, by the southern extremity of the Ural, to the lake Aral, the great empire of Russia is divided into two parts—the northern consisting of the older rocks already described, the southern of the cretaceous and tertiary beds, only interrupted for any extent by the granitic

steppe of the Dnieper and the coal-field of the Donetz, formerly noticed. The distribution of the cretaceous rocks is so irregular, that we can only refer the reader to Sir R. Murchison's map, more especially as the authors admit that this portion of their researches will probably require some modification. The leading result is, that rocks more or less resembling the chalk and green sand of England and Northern Europe-pure white chalk and chalk marl, iron sands and green sands, with many of the same characteristic organic remains--may be traced through Germany and Poland to the remotest regions of the Volga and the confines of Asia. In no part of Russia does this formation assume the Mediterranean type of character, which the cretaceous deposits present in Southern Europe, in Africa, and part of Asia.

For the same reason we shall pass shortly over the tertiary strata, among which the authors recognise the three great divisions established by Mr. Lyell. Some beds of Eocene age at Antipofka, on the Volga, show a remarkable lithological agreement with portions of the London clay, and are really

undistinguishable from masses of the Bognor rocks, in which 'the very same shells occur.' In this place, too, there seems to exist that passage from the secondary to the tertiary rocks, which has been in vain sought in Western Europe, but which MM. Dubois and Huot have observed in the Crimea, and which probably also occurs in some parts of European Turkey. In the Miocene, or middle tertiary, the authors place the wellknown salt mines of Wieliczka, which, however, lie within the Austrian dominions. Sir R. Murchison states that the masses of salt form great concretions in clay, and appear to have been produced along an ancient coast line of the Carpathian mountains.

The more recent tertiary or Pliocene beds are found especially in the singular basin of the Caspian. In the early days of physical geography it was generally supposed that some subterranean communication carried off the surplus waters of this inland sea to the Mediterranean, and prevented it from overflowing its banks. Inquirers then little knew the vast powers of evaporation, the enormous machinery which nature employs to convey moisture to the fields and feed the innumerable rivers. It was therefore with no small incredulity that many received the information of M. Parrot, that the Caspian was in reality far below the level of the Euxine. Though, probably from peculiar atmospheric conditions, his barometric estimate of its depression considerably exceeded the truth, yet recent detailed trigonometrical levellings establish the general fact that this sea, with a

large district around, is far below the surface of the ocean. The mean of three measurements, all closely agreeing, makes the surface of the Caspian nearly eighty-three and a half English feet below the Black Sea, from which it is divided by a low steppe, perhaps not rising much more above the level of the latter. To this very interesting fact, geology has added another not less interesting. The Aralo-Caspian Sea, as it is named by Humboldt, has at one time extended far beyond its present limits, not only over the low sandy deserts of Khivah and the plains east of Tiflis on the south, but far to the north-east through the Asiatic homes of the Kirghis and Turkomans, and on the west, through the steppes of Astrakan and the Crimea, to the shores of the Euxine at the mouths of the Danube. The evidence of this fact given in this work consists in the occurrence through all these regions of tertiary beds, including a peculiar suite of fossil shells. These are not marine, as in the older rocks, but are 'analogous, and to a great extent identical, with ' those of the present Caspian Sea, in which the univalves (with “the exception of one doubtful species) are of fresh-water origin, 'associated with forms of Cardiaceæ and Mytili, which are common to partially saline or brackish waters.'

At a more recent period, this vast Mediterranean had its limits greatly contracted, Sir R. Murchison and his associates argue, by the elevation of portions of its bed, cutting it off from the Black Sea on the one hand, from Lake Aral on the other. It still, however, was much larger than at present; and the sandy steppes. of Astrakan, covered with Caspian shells, and the wave-worn cliffs of Mount Bogdo, once an island in that sea, are traces of its ancient abode. But our limits forbid us to enlarge on this very singular though obscure subject, many essential details being still unknown, and we turn with the authors to another different yet no less important feature in the physical geography of this region.

This is the mountain chain of the Ural, fully described in the second part of this work, and illustrated, in reference to its picturesque features, by some very beautiful sketches from the pencil of Sir R. Murchison. From its southern extremity in lat. 461° near the northern shore of Lake Aral, to Mount Sabliu in lat. 65°, its direction is very nearly due north and south, and thus it is fully entitled to be considered as one of those meridian chains whose peculiar metallurgic character has been so well described by Humboldt. Beyond Mount Sabliu it first turns considerably to the north-east in the Obdorsk mountains, and then, bending again almost at a right angle to the northwest, ends in Vaigatz Island in the Arctic Sea, in lat. 70°, and

6

almost on the same meridian (60° E.) on which it took its commencement, 1600 miles to the south. The northern portion of this chain is very little known, and even in lat. 60°, where mines begin to be worked, dense forests and impassable marshes • very frequently obscure the watershed, which is diversified

solely by occasional stony peaks, lifting their heads through 'monotonous and silent woodlands, which would to this day ' have been peopled by a few wild Voguls only, had not the

precious ores led the Russians to colonize and clear them.' It is only in the vicinity of the mines, especially from Ekaterinburg to Bogoslofsk, that the colonists have in some degree subdued the wildness of nature.

In these districts,' say our authors, all difficulties have, in truth, vanished before the perseverance and energy of the Russian miners, whose labours have thinned the forests, erected commodious and often splendid buildings, drained the marshes, filled the gorges with lakes (for water is their great mining power), and rendered the tracts around their Zavods the residence of a population more advanced in knowledge than any with which it was our lot to meet in the greater part of the Russian empire. Yet in no work of geography or statistics can the general reader acquire an adequate conception of the highly flourishing condition of these centres of industry, each more populous and thriving than many towns which are marked on maps in large letters ; and though it is not our object on this occasion to enter into economical details, we cannot avoid stating that these establishments, both Imperial and private, often contain many thousand industrious workmen, whose houses and essential comforts we have seldom seen surpassed in the manufacturing towns of Europe.'-Vol. I. p. 346.

. In reading of this mountain chain, so many hundred miles in length, we are apt to imagine that it must be characterized by summits of corresponding elevation, and feel somewhat disappointed to find its highest peaks* never reaching to 6000 feet, whilst the larger portion is only 2000 to 2500 feet, or even lower.

•When approached by the usual high road from its western or European flank, the North Ural of the Russian miners appears little more than a low, hilly ridge, for the most part densely wooded; and although a line of rock appears at intervals, the Ural mountains of the traveller's imagination are reduced, when they appear in sight, to a mere range of mounts, seldom exceeding in apparent height the Vosges between Metz and the Rhine. Their real height is, however, more considerable, the deception being produced by the traveller having already gradually ascended to some altitude above the sea

* Mount Sabliu, 4000 feet ; Tolpas-is 4500 feet; Konjakofski, 5397 feet; Mount Iremel, 5075 feet.