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I have also found that the temperature of a working spot in Huel Abraham, at the 180 fathom level, where the difference of atmospheric pressure was 0.964, or nearly one inch, when other circumstances, such as number of men, current, blasting of rocks, &c. &c. were similar, that the difference of temperature was only from 14° to 2°; it being 78° when the thermometer was lowest, and 7910 to 80° when highest.

If these remarks appear to contain any further necessary information respecting the temperature of our mines, in continuation with what has already appeared, your inserting them in the Annals, will much oblige your humble servant, M. P. MOYLE.


On the Transition Formation of Sweden. By Dr. Forchhammer. (To the Editor of the Annals of Philosophy.)


THE curious facts respecting the transition formation of Norway, which were discovered nearly at the same time by two German geologists, MM. Von Buch and Hausmann, have excited a great degree of interest, and although much which was at first supposed to be peculiar to the mountains of Scandinavia, has been found in other countries; and much which was imagined to be an exception, appears now to lie within the rule; yet enough remains to distinguish this formation from all others, and to show that the chemical power, which acted so strongly in the formation of the primitive rocks of the north, exerted its influence equally on the transition formation. It ought not to be forgotten, that a long time before the geologists now mentioned made their discoveries, Hissinger had made known a number of facts on this formation, with regard to Sweden, and several writers of minor note in respect to Norway; but the most interesting had not been observed, and the rest had not been connected in such a way, as to give any precise idea about the relative age of these formations, so as to compare them with those of other countries. The German geologists found, that porphyry, syenite, granite, in the neighbourhood of Christiania, rested on limestone and slate, and, while the first rocks contained zircon, feldspar, hornblende, paranthine, epidote, beryl, molybden, the others contained the fossils of marine animals. With respect to Sweden, M. Hausmann has given some very interesting notices, principally about the transition trap of Westgothland, and the transition porphyry of Dalerne. A few years

ago, Dr. Wahlenberg, of the University of Upsala, celebrated for his travels in Lapland, his discoveries relating to the geography of plants, &c. gave an account of the extent of these formations in Sweden, which, though it mostly concerns their geographical connexion with the primitive formations, and the fossils imbedded in them, affords, nevertheless, a great deal of information. Two papers have appeared; the first on the geological formation of Sweden, printed in the first volume of a periodical work, called Svea; the second is a paper on some petrifactions, which has been communicated to the Society at Upsala, and though printed several years since, has not been published, and a few copies are only in the hands of the friends of the author.* It is much to be regretted that the author has not imitated the above mentioned travellers, in stating what he owes to the labours of his predecessors; so that it is often difficult in his works to distinguish his own discoveries, and even his own observations from those of others. We are going to notice such of M. Wahlenberg's observations as appear new to us, and we shall add such facts from preceding observations as will be necessary for illustration. It is to be regretted that we are not able to do the same with regard to Norway; but except the transition formation round Christiania, very little is known. We may, however, expect much from the zeal and information of several travellers, who have been some years occupied in a thorough investigation of the geological nature of this extensive country.

Every thing in the transition formation of Scandinavia, the nature of its rocks, its position with respect to the primitive mountains, its geographical situation, bears a peculiar character. Rocks of every description are found in it, mostly distinguished by their crystalline structure. It was in Scandinavia that granite was first discovered to be a member of the transition formation. Syenite occurs likewise frequently, and of the numerous varieties of the trap family, the two extremes, crystalline greenstone on the one side, and basalt and amygdaloid on the other, have both been observed. Sandstone and quartzrock, granular and compact limestone, clayslate, siliceous slate, alumslate, and even beds of whetslate occur. The slate itself is frequently bituminous, so much so that it burns; and even thin beds of coal occur at Billingen, in Westgothland. The shale which contains much bitumen is free or mostly free from lime; it is then an excellent alumslate, and a number of alumworks are supplied with it. It is distinguished from the alumslate of other countries, and the bituminous shale which is used in the alum manufactories in Scotland, by containing, besides sulphur and alumina, a sufficient quantity of potash, so that nothing is

Om Svenska Jordens Bildning af G. Wahlenberg i Svea. Tidskrift sor Vetenskap och Konst Foresta Hæftet. Upsala, 1818.

Petrificata Telluris Svevanæ examinata a G. Wahlenberg.

[blocks in formation]

necessary but to burn the slate, and to allow it afterwards to remain sufficient time exposed to the atmospheric air, that the sulphate of peroxide of iron thus formed may be decomposed by the alumina and potash, and at last to dissolve the alum. This slate, when so bituminous as to burn, is used as fuel in the alum manufactories. Large round masses, of a pretty pure black limestone, highly impregnated with bitumen (swinestone, anthracolite, Werner) occur every where in this alumslate. Round balls of sulphuret of iron and sulphate of barytes are likewise not


The sandstone of this transition formation is distinguished from that of most other countries by its composition which is similar to that of granite; felspar, and even mica, are necessary to its composition; quartz being always in the greatest quantity. The almost absolute want of all useful metals in the whole formation distinguishes it likewise from the transition formation of most countries, and when compared with the primitive mountains of Scandinavia, which almost every where contain rich iron ores, which have copper in abundance in some places, rich mines of cobalt and silver, and where even gold has been found on different places, such a deficiency of metals must certainly excite surprise. For in other countries the rocks, and principally the slate and limestone of the transition formation are as rich as the primitive rocks. In two places of the transition rocks in Scandinavia, attempts have been made to work mines of galena; one in Scaane, near Cimbrisham, and another in Norway, not far from Stroemsoe, but both have failed.

The primitive mountains when compared to those of the Alps, exhibit a very material difference, both in external appearance and composition. The mountain chain which separates Norway from Sweden does not, at its highest point, attain 8000 feet, but it surpasses on the other hand the primitive chain of the Alps both in length and breadth. Its rocks are mostly such as it would be difficult to say whether they are gneiss or granite. From the main ridge, numerous parallel ridges of the same rock extend to the Gulf of Bothnia and Baltic Sea, thus forming a number of valleys and plains, which begin at the coast, and terminate at the neighbourhood of the boundaries between Norway and Sweden. In these plains, most of which likewise consist of primitive rocks, the richest beds of magnetic iron ore are found, such as at Daunemora, Haesselkulla, &c.; but it is also in these valleys and plains, that the transition formation has had room to expand, with, however, this great difference from most others, that it contains many crystalline rocks. These rocks of the transition formation are confined comparatively to the lower places, with some remarkable exceptions however, and it is a very interesting fact, which we owe to the observations of Dr. Wahlenberg, that each of the greater lakes of Sweden has its transition formation, which extends in regular beds on the


shores. The regularity of the beds, together with the small angle of inclination in general, occasioned the slaty and calcareous rocks of this formation, which contain frequently a great number of fossils, to be considered as belonging altogether to the secondary rocks; while the crystalline sandstones or quartz rocks, the porphyries, the syenites, and granites, are, without hesitation, placed among those of the primitive class. The fossils, however, show sufficiently that these rocks have been formed early after the existence of organic life on the earth. "They are, says Dr. Wahlenberg, "mostly entomostracites (entomolithes Lin.) and orthoceratites, which both, more than any other petrifaction, differ from animals now existing, and prove their great age. Both are of considerable size, and thin, which evidently proves the perfect quietness of the medium in which they lived. Very remarkable are, in this respect, the entomostracites, frequently a foot or more long, and the cylindrical orthoceratites, amounting to two yards in length, which latter lie perfectly entire in the limestone. If we consider further, that a great number of the entomostracites had eyes, and that both they and the orthoceratites exist in very great number, we must be surprised at the powerful organisation with which nature began at once in the north." The ridges of primitive mountains, which spread out from the main ridge, separate of course all the different parts where the transition formation is found, and gives them the character so peculiar to Scandinavia, which is, that the transition formation forms a number of different systems, originally limited on all sides by primitive mountains, having, therefore, no immediate connexion with each other, and generally containing the same kinds of rocks, though often in a different order of superposition. One great exception of this law exists, however, in respect to three chains of mountains, that seem to spread from one point, and thus to be connected with each other. This point seems to lie in the main ridge itself. Helagsfjaellet, Svukkujaellet, are mountains composed of sandstone, situated in this main ridge to the east of Roraas, in Norway. From these one branch passes to the south of Norway; the great lake Mjoesen, which terminates on the west side of the Firth of Christiania, is partly bordered by transition rocks of this system. Another branch passes into Jemteland in Sweden; it seems to terminate at the Storrjoe (large lake) in this province. A third branch passes into the province of Dalerne, and terminates at the lake Siljan. It is extremely remarkable that all these branches have their beds of fossils only at that end which is furthest from the main ridge, when they reach the neighbourhood of the large lakes; and it is evident that the closest connexion exists between the fossils of the transition formation and these lakes.

Sandstone is the rock which is of all transition rocks most abundant in the main ridge. The mountain Svuddu, which, according to the measurement of Tillas, is 4422 feet high, and, according to the measurement of Hissinger, 4693 feet, is a conglomerate, which consists of the same materials as the rest of the Scandinavian transition sandstone; and Hausmann has identified it with those of other parts of the Scandinavian transition formation. The same author mentions an impression on the surface of a piece of sandstone which he found in the inn at Idre, where this sandstone is very frequent in the country around. It seemed to belong to the stem of a fernlike plant, such as are frequently found in the shale of the first coal formation. This is the only instance where fossils are mentioned to occur in in this sandstone; some doubt may, therefore, be entertained, whether it is not merely a lusus naturæ. If it really was an impression of a plant, it would be a direct proof that this sandstone or quartz rock belongs to the transition formation; while some geologists are nevertheless of opinion, that it is a member of the primitive class, principally because its position is frequently unconformable with the gneiss upon which it rests. This, however, does not prove much, because slate and limestone are, with few exceptions, conformable with the sandstone, and they contain numerous fossils. Besides, in some places not far from Christiania, in Norway, sandstone occurs even upon slate and limestone. Upon this sandstone and conglomerate of the mountain Svuddu, and a part of the main ridge in the neighbourhood, in the Swedish province of Dalerne an extensive porphyry formation rests, which furnishes the materials for the excellent works of art that are made at Elfdale, now the private property of the King of Sweden. The porphyry extends from the main ridge as far east as Mora; it is mostly of a red colour, the compact mass being either siliceous slate or hornstone, or compact feldspar. The sandstone passes distinctly into this porphyry. Breccia of bits of porphyry cemented together by compact feldspar and syenite likewise occur. The syenite is remarkable, as it furnishes a new analogy between the formations of Dalerne and the country round Christiania; it occurs near Aasbye, and contains zircon, which is so characteristic of the transition syenite of Norway. The beds of sandstone, porphyry, and syenite, where a distinct stratification may be observed are in general almost horizontal, the angles never exceeding 20°. On the north side of the Lake Siljan, a number of beds of limestone alternate with beds of granite, both in a nearly vertical position, and in a direction nearly north and south; their elevation above the lake amounts from 150 to 200 feet. On the south-east end of the lake, from Ickaan to the church of Rattwick, much granite is found with few and thin beds of limestone; near the church of Rattwick, a bed of limestone occurs, with grains of sand, and destitute of

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