Графични страници
PDF файл
ePub

crystallization. You will at once see that this fact, being established, will prove of importance in enabling us to explain many appearances which have hitherto puzzled geologists in their attempts to account for the origin and formation of rocks.”—Letter from Alexander Turnbull, Esq. Civil Surgeon, Darwar, East Indies.

7. Account of a Libellulite found at Solenhoffen.--Last spring there was found in the famous quarries of lithographic limestone at Solenhoffen, near Pappenheim, in Bavaria, a beautiful petrifaction of an insect of the genus Libellula, represented at Fig. 4. Pl. 3. These quarries are already well known, from the numerous fossil species of marine and fresh water animals they contain. The body of the fussil libellula is disposed in the direction of the slaty structure of the limestone, and is distinguished from the stone in which it is contained, not by any particular colour, but its greater smoothness. The head is roundish, and not very broad. The neck and the first pair of legs are distinctly visible, but the other feet were not seen.

The thorax is the most prominent part of the animal, but becomes gradually flatter towards its extremity. The four wings are spread out, and very well preserved, and single veins are observable in some of them. The abdomen is cylindrical, is thinner towards the middle, expands again, and terminates in a notch. The globular head, the horizontally expanded wings, the cylindrical abdomen, and the total habitat, shew that it belongs to the genus Aeschna of Fabricius, and is distinguished from the Aeschna grandis only by its greater size. The insect just mentioned, measuring from tip of one wing to tip of the other, three inches; whereas in the fossil species, the length is thre, and a half inches, and all the other parts are in proportion larger. In the same block of stone with the fossil libellula, was a small asterias, or sea-star,-a fact which confirms the mutual occurrence, in this rock, of land and marine animals.-Vide Leonhardt's Zeitschrift.

8. Beds of Sea-shells, nearly in a fresh state, 200 feet above the level of the Sea.— The following observations, (says Berzelius), which I had an opportunity of making on the west side of the Scandinavian peninsula, will serve as an additional proof of the gradual rise of the Scandinavian land above the level of the sea. It is known that, on the sea-coast, and in

[ocr errors]

the islands at Uddevalla, and also on the whole sea-coast of Southern Norway, there are here and there banks of seashells, sometimes 200 feet above the present level of the sea. The shells are, in general, well preserved, none are calcined or weathered, and all of them are of species that still live in the neighbouring sea. The horizontal beds in which they lie, shew that they have been quietly formed here, and that they were formerly the bottom of the sea. One of them, the Lepas balanus, is always attached to the rocks of the coast ; so that, during the motions of the surface of the sea, it is momentarily above its surface. Brongniart, with whom I visited these banks at Uddevalla, remarked, that if the sea, at any time, covered these places, that we would probably find lepades or barnacles adhering, if any of the rocks could be exposed. We searched for exposed portions of rock, and soon found them, with barnacles adhering, which had remained attached from the period when Uddevalla was 200 feet under the surface of the sea. I consider this as the oldest and most certain of all those marine testimonies which go to prove that the Scandinavian land has risen above the sea ; for a fall or sinking of the sea 200 feet around the whole coast is not to be thought of. What raises the land, and how and when will its elevation be finished ? But who would venture to answer these questions ?

9. Greensand formation in Sweden.--Nilson has announced, in the Stockholm Transactions, the discovery of the greensand in Schonen. It contains, besides univalve and bivalve marine shells, different fossil land plants. The green sand of Schonen may be considered as the termination of the great tertiary series of rocks which extends from Germany, under the waters of the Baltic, until it terminates in the higher lying parts of Schonen.

10. Coal of Höganäs.—This interesting deposite appears to occupy, in the geognostical series, a place between the old coal formation and that of the brown coal.

11. Hill of Magnetic Iron-ore.--Menge describes a hill of magnetic iron-ore he met with at Kuschwa, in Siberia, 400 feet high, which rises through primitive greenstone. The iron-ore is associated with sodalite and augite. On the west side of the mountain, he observed a remarkable amygdaloid rock, in which the basis is of garnet. The amygdaloidal masses are calc-spar, and the vesicular cavities are lined with crystals of scapolite.

12. Hyæna Cave.-M. Billaudei, civil-enginer at Bourdeaux, discovered in a quarry on the banks of the Garrone, a cavern, in which he found a quantity of the bones of various animals, among them jaws of the hyæna, of the lion, or the tiger, and of the badger, bones of the fox, &c.

MINERALOGY.

13. Crystallizations of Sulphate and Carbonate of Lead observed by M.Hartmann. The following forms of sulphate of lead (Prismatic Lead Spar) were observed in a series of beautiful specimens, from a vein in transition clay-slate, near the smelting works of Tanne, five hours

from Brunswick, by the translator of Beudant's Mineralogy, M. Hartmann, and by him communicated to us :1. (Př+ 0)3. P – 00. very frequent in crystals half an inch in length, which are often tabular. 2. (Př +60)z. Př resembling fig. 1. Mohs's Treatise, vol. ii. 3. (Př +60)3. Př. P-0. 4. (Př +00)! Pr +00. 5. P+0. P. 6. (Př +00). PT. Ēr. 7. (Př+00.)3. Pr + Co. P-00. Twin crystals exhibiting the form represented in Pl. III. Fig. 5. M, Hartmann observed, from the same place, the following combinations of carbonate of lead, or white lead spar :- 1. P. 2. P. (Pr + c)3. Fig. 54. Pl. 91. Hauy. 3. M. I. s. (Hauy's Letters) 4. M. I. f. u. Fig. 36. Hauy. 5. M. I. s. y. Fig. 57. 6. M. e. 1. f. k. u. Twin, or rather triple crystals, grouped according to the law in Fig. 65. Pl. 93. Hauy, and the termination of the planes P. n. i.

14. Geognostic Position of Platina in America.-Hitherto this metal has been found, in the New World, only in the alluvial districts of Choco and of Brazil; but Mr Boussingault has discovered roundish grains of platina, mingled with native gold, in veins in the province of Antioquia.

These veins traverse a formation of greenstone, diorite, and syenite.

15. Jet discovered in Wigtonshire.Beautiful specimens of this mineral have been found between a bed of peat and yellow clay, in the peninsula formed by Loch Ryan and the Irish Channel, by Sir Andrew Agnew.

16. Geognostical Distribution of Gold in the Uralian Mor tains.-The gold-bearing districts in the Uralian mountains

rous.

[ocr errors]

almost universally composed of magnesian rocks; of these the most frequent is talc-slate, and less abundant are serpentine and ophite. The gold occurs either disseminated in these rocks, or in quartz veins which traverse them, where it is generally associated with varieties of iron pyrites, which are usually aurife

Beresowsk is a remarkable point in the Urals: the whole of the district is talc slate, surrounded by serpentine, and traversed in all directions with an infinity of auriferous quartz veins. In one place Mr Menge found gold in decayed syenite. Erdmann, in his account of the interior of Russia, gives an interesting account of the alluvial gold of that country. The alluvial deposit, on the left bank of the Beresowka, is about thirty feet thick,—the upper layer a loam, underneath which, and forming the great mass of the alluvium, is sand, of which the coarsest kinds are lowest. The gold occurs in the sand, and in largest quantity, in the deepest seated, and coarsest varieties. Two opinions as to the mode of formation of this alluvium have been proposed ;-according to the one, it is believed to be derived from the neighbouring hills, because it is intermixed with masses of quartz, and fragments of brown iron ore, both of which occur in the mountains in the vicinity ; the other opinion, that it has been brought by a flood from a distance, receives additional support from the circumstance of it sometimes containing bones of tropical looking animals, and the gold being different from that of the neighbouring mountains. This alluvium, or auriferous sand, occurs chiefly on the east side of the Urals, extending from Bogislowich smelting establishment, to the Polkowischen mine, an extent of 1000 wersts from north to south. It is

very

rich in the district between Nischni-Tagilskoi and Kuschtymskoi, and the district Lenowka and Lugoowka. There is over the sand a layer of peat and black earth, 1, archines thick. The uppermost bed is richest in gold, the middle less so, and, at the bottom, the gold is scarce. The sizes of the single pieces of gold which have been met with, are worthy of being noticed. The Governor of Perm presented the University of Dorpat a specimen worth 800 rubles. When the Emperor Alexander visited the Mines of Orenburgh, he was presented with twenty-nine different pieces, one of which weighed eight pounds.

In the royal

mines of Slatoust, there was raised, in April 1825, within twenty-four hours, a series of beautiful specimens. Several weighed from five to nine pounds, and one sixteen pounds. This bed of sand also affords other metals. Soon after the commencement (1819) of washing for the gold of the Urals, many grains were noticed amongst the grains of gold,these were of magnetic iron-ore, iron-pyrites, lead-glance, brown iron-ore, &c. In the year 1823, Lubarsky detected along with these, also platina, iridium, rhodium, and osmium.

17. Geognostic situation of the Siberian Platina.-M. Menge of Lubec, one of the contributors to our Journal, who is at present travelling in Siberia, gives the following account of the geognostic situation of the Siberian Platina. Being very desirous of examining the locality of that mineral, he proceeded to the spot, on the western side of the Uralian range, with one of the officers of the mine of Nischnin Tagil. There he found primitive clay-slate, much traversed by quartz veins on the banks of the Utka. The ridge of the Urals where he saw it, was composed of Serpentine : at the foot of a hill, named Pugina, which is composed of serpentine, resting on talc-slate, he found, under the soil, in decomposed talc-slate, a quantity of platina associated with gold and native lead. Forty hundred weight of this slate afford half a pound of platina. The slate is a compound of smoke-grey quartz and common talc-slate. Grains of platina were, in all probability, , also disseminated through the quartz. The serpentine abounded in grains and crystals of magnetic iron-ore; and, in decomposed varieties of the same rock, grains of platina, but none of gold, were met with. On the east side of Pugina, the serpentine appears first in diallage rocks, and in this rock platina also

North-east from Kuschwa, near to Nischnin-Turah, platina occurs in blue limestone, connected with disintegrated green porphyry.-The occurrence of gold and platina, in quantity, in serpentine and talc-slate, is a fact worthy of the attention of those proprietors in Scotland, where these rocks abound, as in Shetland, and various parts of the mainland of Scotland.

18. Cordierite found in Norway. This mineral has been met with in Norway associated with Wernerite, quartz, garnet, and mica. The pierre de soleil probably belongs to this species. The Norwegian cordierite, when cut and polished, exhibits a stellular opalescence, resembling that of the stellular sapphire.

Occurs.

« ПредишнаНапред »