ash and cinder conglomerate exists but in one place on the Island of Law. rence, in Portland Bay. Cliffs of this singular compound rise there 150 feet. The author's impression is that the source was a submarine volcano to the south-west, -the course of the prevailing wind and current; and that the ashes and volcanic dust were received in some sheltered bay, since raised with the coast. The extinct volcanos are in the form of lakes and mountains. The lakes are depressions usually on slight eminences. Terang, Elingamite, Purrumbete, Wangoon, and Lower H are fresh, while Keilambete and Bulleenmerri are salt. The shallow saline lakes of the plains were not former craters. The depths of some of these lakes are 50, 100, 150, 200, and 300 feet. The Devil's Inkstand of Mount Gambier is 200 fet The banks vary from a few feet to 300 feet in height above the water. The cir cumference varies from 100 yards to 7 miles. The thickness of the ash increases with the distance from the crater, but is always thickest on the eastern side At Lower Hill, at a quarter of a mile from the bank, on the northern quarter, it is 80 feet deep, while at a mile off, on the eastern side, it is 150 feet. The volcanic hills vary from a few yards to above 2000 feet above the sea-level. The depth of the dry craters runs from 50 feet to 300 feet. Gambier and Schanck are within the South Australian border. The former has three fine lakes. The latter is a dry basin, known as the Devil's Punchbowl. Porndon is a cone of very light cinder, elevated amidst the remarkable rises. Leura is a broken crater on the edge of the rises; while Purrumbete is a beautiful sheet of water, a few miles distant, which once, as a crater, discharged vast quantities of ash. The other principal volcanes of Western Victoria are Buninyong, Blowhard, Noorat, Gellibrand, Napier, Franklin, Cavern, Shadwell, Lower Hill, Clay, Elephant, Eckersley. No adequate impression can be received as to the age of the activity of these cones and craters. There is a freshness in most of them indicative of a comparatively modern date. The natives have traditions of the eruptions of several of them. As loam overspreads the recently scattered auriferous drift of several of the diggings, it would not appear to have been of great date. It occurs on tertiary limestone to the west, and underlies it as well.

Mr. ANTONIO BRADY exhibited some flint instruments, together with bones of Elephas primigenius and Echini, obtained by him only a few days since from the drift at St. Acheul, near Amiens. He stated that although found only a few feet above the chalk, in the drift, in true association with the bones and shells of extinct species, still, from the composition of the drift, there was in his judgment no proof that the animals and the makers of the instruments lived at one and the same time. From the heterogeneous and rolled state of the materials, there was great reason to believe that they had been disinterred from their original resting-places by some sudden torrent or convulsion, and been reinterred in their present association. Th drift had clearly never been lifted by the hand of man, but is doubtless in the state in which it was deposited, whenever that may have been.

On the Aqueous Origin of Granite.

By ALEXANDER BRYSON, F.R.S.E., P.R.S.S.A.

In this paper the author referred to the labours of Dr. William Smith, who published his Tabular View of the British Strata' in 1790, and remarked that since that period geology had been studied mainly in the direction of paleontology. Physical, chemical, and dynamic geology were left almost unregarded by the great masters of the science, who generally accepted the speculations of Hutton and the experiments of Hall as demonstrating the igneous origin of the primary rocks.

The author stated that the Huttonian theory was most ably attacked, and, in his opinion, overthrown, by Dr. Murray in his 'Comparative View of the Huttonian and Neptunian Systems of Geology, a work most unaccountably overlooked. Since that time it had suggested itself to the sagacious mind of Davy, that the occurrence of fluids in the cavities of crystals seemed to point to an aqueous origin. He also alluded to the writings of Brewster, Sivewright, and Nicol in the same field: also to Becquerel, Fuchs, Bischoff, and Delesse, who have taken up the subject of the aqueous origin of rocks from a chemical point of view. The author then laid before the Society the result of ten years' experimental investigation into the structure of

- rocks relative to their formation, more particularly granite. While examining microscopically the various pitchstone veins abounding in Arran, he was much struck with the similarity of their structure, and the marked difference they exhibited when compared with sections of granite and its various mineral constituents. On extending his observations to obsidian, marekanite (a volcanic glass from Lake Marekan in Kamtschatka), and also to the well-known glassy obsidian of Bohemia, he found they all exhibited a structure analogous to the pitchstones of Arran. He further found that sections of glass slags, where the heat had been long continued, combined with slow cooling, all presented the same appearances as the sections of pitchstone.

This structure, peculiar to igneously formed substances, he found usually to radiate in a stellate form; and though many slags showed large stars visible to the naked eye, the stellate structure is more easily observed by the aid of the microscope. The character is so marked, that no one whose eye is tutored to microscopic observation can fail to recognize at once a mineral substance of igneous origin.

In granite, on the other hand, the structure, as seen by the microscope, is as persistent as in pitchstone, glass, and obsidian, but totally different.

In the many experiments which the author had tried with granites from various localities, he had never succeeded in obtaining one instance of stellate structure, while the constant occurrence of cavities containing fluids convinced him that, if pitchstone and glass are types of igneous-formed substances, granite must be of aqueous origin. In the fluid cavities so abundant in topaz, Cairngorum, beryl, tourmaline, and felspar, all constituents of granite, he found the same appearance prevailed. These cavities are seldom entirely filled with fluid, an air-bubble usually occupying more or less of the cavity. After many hundred experiments on such cavities, the author found that when exposed to a temperature of 94° Fahr., the bubble disappeared, the fluid entirely filling the cavity, and at the temperature of 84° the bubble reappeared with a singular ebullition, showing that the air had formed an atmosphere round the fluid. He was thus led to infer that these cavities could not have been filled at a temperature above 84°, and certainly not above 94° of Fahrenheit.

As another proof that these cavities could not have been filled when the temperature of the surrounding rock was higher than the temperature above indicated, the author drew attention to the fact that the bubble of air occupied always a much smaller portion of the cavity than the fluid, a condition which could not obtain, if, as other writers hold, the fluids were enclosed under intense heat and pressure.

For the purpose of accurately determining the temperatures at which the bubble vanished and reappeared, the author constructed an apparatus which he exhibited and described. It consists of a microscope with a hollow iron stage, having a tube in the centre to admit light from the reflector. At one side, and inserted into the stage, is a small tin retort with a stopper; at the other side, a tube is inserted and attached to a reservoir of water, from which the hollow stage and retort are filled. On applying heat to the retort by means of a spirit-lamp, any required temperature under the boiling-point of the water may be obtained in the stage and retort.

Above the stage is placed an iron saucer, in the centre of which an iron tube is riveted, through which the light is admitted; this vessel is filled with mercury, and in it is placed an upright thermometer, with the bulb shielded with cork or any other good non-conductor; by this means it indicates the actual temperature of the mercury bath. The cavity to be observed is cemented with Canada balsam to a plate of glass 3×1 inch, and is floated on the surface of the mercury, so that the glass and mereury are in absolute contact. When the temperature is raised until the bubble nearly disappears (which is seen by its contraction), the spirit-lamp is with drawn, and the vanishing point carefully watched and the temperature noted. The stopper of the retort is then withdrawn, and the stopcock of the reservoir of water opened, so that the temperature of the stage and mercury bath is soon reduced, and the ebullition or reappearance of the bubble takes place, when the temperature is again recorded. By this method the author felt confident that his results were correct, as they always were consistent when observing the same cavity. By means of this instrument the author had found fluid cavities in the trap tuff of Arthur's Seat, the greenstone of the Crags, and the basalt of Samson's Ribs, He had also found that the porphyry of Dun Dhu in Arran, which most geologists assumed as

of igneous origin, was full of fluid cavities contained in the doubly acuminated crystals of quartz for which this remarkable porphyry is distinguished. He also showed doubly acuminated crystals of quartz in the saliferous gypsums of India, both of which were full of fluid cavities, and the quartz impressed with the gypsum; and as no geologist would hold that this formation was of igneous origin, but that the quartz, if not contemporaneous with the gypsum, must have been subsequent, and as the same phenomena were presented by the porphyry of Dun Dhu, he was forced to the conclusion that it was as much aqueous in its origin as the saliferous gypsum of India. The author exhibited a specimen of quartz which contained a crystal of iron pyrites, to which was attached a crystal of galena and also a smal massy zinc blende, while over these three metals was laid a covering of gold. From this specimen he argued, that as all these metals were fusible at a much lower temperature than quartz, they must have aggregated during a gelatinous condition of the quartz; and further, that as the sulphides of the three metals were in chemically combining proportions, any heat which would have fused the quartz would have made an alloy or a slag in which chemical combining proportions could not

occur.

He also exhibited specimens of schorl which he had obtained in the granite of Aberdeen, and drew the inference that schorl, which crackles and splits with a very small increment of temperature, could not have been present during a molten condition of the quartz; and that it was crystallized prior to the solidifying of the latter, as proved by the schorl impressing the quartz. The author, from a careful examination of the schorls in the quartzite of Aberdeen, was led to believe that the quartz, while in the process of crystallization, expanded one twenty-fourth of it bulk, a force which appeared to him to be sufficient to cause all the upheavals and disruptions which had led geologists to account for such phenomena by a molten condition of the primary rocks. If this view is correct, and if the highest peak is granite, as the lowest is known to be granite, the author calculated that as the highest mountain is only part of the radius of the earth, a thickness of the crust of 168 miles is quite sufficient to yield expansive force to raise the highest peak of the Himalayan range. He further stated that the cause of the temperature at which the fluids were confined being higher than the normal one, depended on the rise of temperature which takes place during solidification.

The author, in conclusion, trusted he would soon be in a position to confirm these views when he had finished the investigation of the trap-rocks with which he is now engaged.

On the Laws discoverable as to the Formation of Land on the Globe.

By the Rev. C. R. GORDON.

Results of the Geological Survey of Tasmania. By C. GOULD, B.A., F.G.S. The formations treated of were the upper paleozoic marine deposits and the coalmeasures. The apparent conformability of the two sections was shown, together with their intimate connexion, serving to render their consideration inseparable. The coal-measures exist to a greater or less extent throughout the country referred to, the depth being about 900 feet. The coal-measures of the district might be regarded as constituting two distinct fields, the maximum one of which might be termed the Mount Nicholas Coal-field, comprehending the various portions developed upon either side of the Break o' Day Valley, while to the other the term Douglas River Coal-field might be applied, as indicating the area occupied by the carboniferous formation between Long Point and Bicheno. In the first the position of the prin cipal seams of coal, although highly advantageous to their being worked, is at an elevation of from 1200 to 1500 feet above the sea. There were at least six distinct seams in the Mount Nicholas coal-field, one of which was of superior quality, and 12 feet in thickness. Ever since the discovery of the seam experiments have been made, which, though amply sufficient to prove the value of the coal for domestic purposes and for application to the usual branches of manufacture, have been upon too limited a scale to permit of the determination of its value as a steam fuel. A remarkable shale exists in the north of the island, available as a source of paraffine

and paraffine oil. The Mersey coal-field was one of the very few in Tasmania which are actually worked; for although the extent of coal throughout the island is almost unlimited, there are very few points at which any operations are conducted.

On the Faults of a portion of the Lancashire Coal-field.

By A. H. GREEN, M.A., of the Geological Survey of Great Britain.

In this paper a law was enunciated which appeared to govern the directions of the principal lines of fault in the portion of the Lancashire coal-field lying between the meridians of Wigan on the west and Rochdale on the east.

On the western side of this tract the average direction of the faults is about 20° W. of N.; as we go eastwards the lines of fracture tend more and more towards an E. and W. direction, till in the neighbourhood of Rochdale they are found to run from 45° to 50° W. of N.

An attempt was made to show, on the principles laid down by Mr. Hopkins in the sixth volume of the Cambridge Philosophical Transactions, that this law was a necessary consequence of the elevating forces which produced the upheaval of the coal-field.

The upheaving forces seem to have exerted their greatest force along the northern and eastern boundaries, increasing in each case towards the north-east corner; the western boundary seems to have been a line of upheaval of smaller and more uniform intensity; and on the south, where the coal-measures pass below the new red sandstone, the force of upheaval has decreased to a minimum.

Hence it was inferred that the southern and western boundaries of the coal-field might be considered as remaining undisturbed during the upheaval, while its northeastern corner had been elevated. The extension of the strata produced by this upheaval, as soon as it exceeded their power of cohesion, would cause fissures; and the directions of these fissures, indicated by theory, coincide very nearly with the observed lines of the principal faults.

Comparison of Fossil Insects of England and Bavaria. By Dr. HAGEN, (Communicated by H. T. STAINTON, F.L.S.)

The author remarked that formerly the fossiliferous strata of Solenhofen and Eichstadt in Bavaria had been considered analogous to the English secondary strata, but that later investigations had established that the latter were considerably older. "I must especially call attention to the fact, that the species described by Germar in the 'Acta Academiæ Leopold,' to which hitherto reference has always been made, are described from specimens the outline of which has been artistically painted and completed. I have often examined the types carefully, and can maintain with certainty that this account of them is correct. The Royal Collection in the Academy of Munich, and the collection of Dr. Crantz in Bonn, contain together about 1000 stones with insects, and, even deducting the double stones, thus represent at least 600 specimens.

"Having an opportunity a few weeks back of studying very carefully the Munich collection, I was much surprised at the splendid preservation of many of the specimens. The insects of the Solenhofen strata are almost universally preserved entire ; wings, legs, head, and antennæ are in their proper places; most of the Libellule have their wings expanded. He who, on the sandy shores of the Baltic, has noticed how depositions of insects are now taking place, will admit that these Solenhofen insects must have been dead when deposited. They would be driven by the winds into the sea, thrown on the shore dead or dying, and then gradually covered with sand by the rippling waves. This process took place on the Solenhofen strata extremely gradually and slowly, as is evident from another circumstance; for we frequently find the cavities of insects (the head, thorax, and body) filled up with regular crystals of calcareous spar. Hence the pressure of the stratum overlying the insect must have been very slight, when such delicate parts as the abdominal segments of a dragon-fly could oppose resistance for a sufficient length of time to admit of the formation of crystals.

1861.

8

"The English strata, on the other hand, rarely contain entire insects; generally there are only some part of the wings, abdomen, and thorax, and these besides are usually imperfect. Hence it appears worthy of consideration whether the insects of the English strata do not convey the inference that, through the agency of storms and other commotions, the fragments were tossed about a long time before they found a resting-place.

"There is the less to be said against this conjecture, as the wings of insects (which form by far the larger part of the English entomological fossils) are almost indestructible in water. I have kept the wings of dragon-flies in water for years without observing the slightest change in their texture.

"From a careful study of the fossils of Solenhofen, and a comparison with the published figures of the fossil insects of England, I have deduced two conclusions:"First, that the two fauna are very closely allied, and possibly some species in both formations are identical.

"Secondly, that the fauna of Solenhofen and of the English strata are not only quite distinct from the existing fauna, but also from those of Aix, of the Rhenish peat-deposit of Eningen and Radoboj, and from that of amber, differing not only in species but in genera.

"Almost all the Solenhofen insects will necessitate the construction of new genera, which, however, will often furnish connecting links between some of our existing genera.

"In reference to the Odonata (dragon-flies), which form so large a portion of the insect fauna of the Solenhofen strata, and pieces of the wings of which seem not uncommon in the English strata, we find a remarkable contrast between the fauna of the English secondary strata and the fauna of Eningen and Radoboj. Whereas here, as also in the Rhenish peat, larvæ and pupae of Libellule are found in great numbers, many often lying together, the perfect insects being proportionally scarce; in the Solenhofen and Eichstadt deposits Libellula are precisely the most plentiful specimens (forming rd of all the insects), and on the other hand, up to the present time not a single larva or pupa has been found.

"The absence of larvæ in the Solenhofen strata may be accounted for by the supposition that the waters on whose shores these strata were deposited were salt; just as at the present day numerous Odonata are buried in the sands on the shores of the Baltic, although their larvæ do not live in that sea. The deposits of Eningen and Radoboj, on the other hand, we must conclude were made in fresh water."

On the Old Red Sandstone of South Perthshire.

By Professor HARKNESS, F.R.S., F.G.S.

At the Bridge of Allan, which is situated immediately on the north side of the fault separating the coal-field of Stirlingshire from the Old Red Sandstones on the north thereof, there are seen, on the side of the hill near the well, conglomerates which are principally made up of fragments of trap, and these, in their higher beds, have grey sandstones intercalated with them. These grey sandstones, on ascending the series, occur exclusively; and they are well seen at Wolf's Hole quarry, dipping at 20° N.W., being capped by trap. Here, in the grey sandstones, the remains of Pteraspis rostratus have been found, and in the same strata portions of a Cephalaspis also occur,

A section showing the arrangement of the deposits which succeed these grey sandstones may be seen in the course of the Allan to beyond Dumblane. A continuation of this section may be obtained in the course of the Teith; and the river Keltie, which flows into the Teith about 3 miles below Callander, furnishes the series of deposits which join those of the Teith. Collectively a section may be had showing the nature and the arrangement of the deposits which occupy the area between the fault alluded to as occurring on the south, and the metamorphic rocks of the southern flanks of the Grampians. .

This section exhibits a trough on the margins of which conglomerates occur, these forming the lowest strata.

To these conglomerates succeed deposits which contain Pteraspis and Cepkalaspis, consisting of grey sandstones. Purple strata occur above these, to which