2. On the Relations of the Crystalline Rocks of the North Highlands to the Old Red Sandstone of that Region, and on the Recent Fossil Discoveries of Mr. C. Peach; by Sir RODERICK I. MURCHISON, (Proc. Brit. Assoc., 1855, Ath., No. 1457).-Having referred to his earliest publications relating to the Old Red Sandstone, in 1826 and 1827 (being associated in the latter year with Prof. Sedgwick), the author explained how the classification originally proposed by his colleague and himself had been extended and improved by the researches of Mr. Hugh Miller. Hav. ing stated that his matured and condensed views as to the true equivalents of the Old Red Sandstone being the Devonian rocks of other countries were given in his last publication, entitled 'Siluria,' Sir Roderick called the special attention of the Section to the consideration of the true relations of these deposits to the crystalline rocks of the Highlands. To satisfy his mind on this point, and to see if it was necessary to make any fundamental change in his former views, the author has spent the last five weeks in re-surveying his old ground in Sutherland, Caithness, and Ross-shire, on which occasion he was accompanied by Prof. James Nicol. Obtaining ample evidence to induce him to adhere to his former opinion, that all the crystalline rocks of that region, con. sisting of gneiss, mica schist, chloritic and quartzose rocks, limestones, clay slate, &c., were originally stratified deposits, which had been crystallized before the commencement of the accumulation of the Old Red Sandstone, he first gave a rapid and general sketch of those ancient rocks, whose crystalline character he thus attributed to a change, or metamorphism, of their pristine sedimentary condition. They have a prevalent strike, varying from NE and SW to NNE and SSW, and in the northernmost counties of Scotland their prevailing inclination is to the ESE or SE, usually at high angles. In combating a theoretical idea, which had only very recently been applied to the crystalline rocks of Scotland, viz., that their apparent layers were simply a sort of crystalline cleavage, by which the different minerals were arranged in parallel folia or laminæ, and were independent of the original lines of deposit, he showed how every geologist who had long studied these rocks in Scotland had formed an entirely different opinion. Hutton, Playfair, Hall, Jameson, M'Culloch, and Boué, all believed that the variously constituted and differently colored layers of these rocks truly indicated separate original deposits of sand, mud, and calcareous matter. He cited numerous cases of interstratified pebble beds and limestones as completely demonstrative of their true original status. Alluding to the real distinction between stratification and cleavage, as first defined by Prof. Sedgwick, he expressed his belief that, whilst in no part of the Highlands did there exist that perfect and symmetrical fine crystalline cleavage which prevails in North Wales (the thick slates of Ballyhulish and Easdale usually cleaving in coincidence with the laminæ of deposit), there was, nevertheless, a very marked and prevalent division of all such crystalline rocks into rhombic and other forms by rude cleavages and very decisive joints.

In describing two traverses which he made across the direction of these crystalline rock masses in the north coast of Sutherland,-the first, twenty-eight years ago, with Prof. Sedgwick, the other, in the weeks preceding this meeting, with Prof. Nicol,—and, in mentioning

with due praise a memoir, of intermediate date, by the late Mr. Cunningham, it was stated, that the oldest, or lowest, visible stratified rock in that region was a very hard, gray, quartzose gneiss, traversed by veins of granite, as seen on the shores of Loch Laxford, Cape Wrath, the escarpment of Ben Spionnach, in Durness, and other places. At the last-mentioned locality, and near Rispond, the older gneiss is unconformably overlaid by a copious series of quartz rocks, of white and grey colors, occasionally passing into mica schists or flagstones, and, also, into stratified masses, which are truly gneiss, inasmuch as they are composed of quartz, mica, or feldspar. With a copious interstratification of bands of limestone, near their lower parts, these crystalline rocks are very clearly exhibited between Loch Durness and the Whiten Head on the coast, or between Ben Spionnach and Loch Eribol, in the interior. It is in one of the beds of limestone subordinate to the lower white quartzites of this great series, some courses of which range into Assynt, in south-west Sutherland, and to Gairloch, and Kishorn, in Ross-shire, at Balnakiel, in Durness, that Mr. Charles Peach recently discovered organic remains; and, as their discovery has led to certain suggestions, including one which would consider these crystalline rocks as the representatives of the Devonian or Old Red Sandstone formation, the author begs to show why such an opinion seems to be untenable, and to point out that, both from their physical position and the nature of the imbedded remains, they are most probably of Lower Silurian age. For, whether the section be made across the va rious strata between Loch Durness and Loch Eribol, or from the latter to Loch Hope, the same limestones subordinate to quartz rocks of white and grey colors (including some rare coarse white grits, as in the summit of Ben Spionnach), and associated with many siliceous concretions (of various colors, red and dark grey) are distinctly and conformably overlaid by and pass up into micaceous quartzite and dark colored schists, both chloritic and talcose, which are followed by other and differently composed stratified masses, having the character of gneiss. Along the north coast these overlying masses extend to the west shore of Loch Tongue, before they are interfered with by any mass of granite; and it is, therefore, unquestionably true, that the band of limestone containing the fossil shells discovered by Mr. Peach is one of the lowest members of this great crystalline series of stratified rocks of very diversified characters. It was suggested that the fossils in question being of a whorled or circular form might prove to be the Clymenia of the Devonian rocks; but this suggestion is now set aside by Mr. Salter, who, after a close examination of the fossils submitted to him by Sir Roderick Murchison, has unreservedly expressed his belief that they are not chambered shells, and cannot, therefore, be either Clymenia or Goniatites. Mr. Salter suggests that they much resemble the Lower Silurian genus Maclurea, with which, however, they cannot be identified, as it is a sinistral shell, whilst the Durness fossil is dextral; and, on the whole, he is disposed to refer them to the genus Raphistoma, a shell which has been found in the Lower Silurian limestones of Ayrshire, (Girvan). So far, therefore, as the fossil evidence goes, it is in accordance with the geological succession of the region, and countenances the idea expressed some years ago by Prof. Nicol and the

author, that many of the stratified crystalline rocks of the Highlands would prove to be the metamorphosed equivalents of the fossiliferous Lower Silurian rocks of the south of Scotland.

Sir Roderick adverted to a feature in the older series of crystalline rocks of the west coast of Scotland, which still required to be more accurately defined than had hitherto been done. Prof. Sedgwick and himself had formerly called attention to the occurrence, near Ullapool, of a red conglomerate coarse grit, subordinate to the crystalline rocks, but which must not be confounded with the true Old Red series, as developed on the north and east coasts of the counties of Caithness, Ross, Inverness, Nairn, Moray, &c. During his excursion of this year, Prof. Nicol and himself saw, near Inchnadampff, in Assynt, a similar inter• position of hard red conglomeritic grit, resting at once unconformably in the older gneiss; but bad weather prevented their ascertaining whether this mass, as exposed on the road to Loch Inver, is really sur mounted by the quartz rock; nor were they able to determine the rela tions of the great red conglomerates of the mountains of Coul More, Sulvein, Coulbeg, and Canish, to their ancient red rock. He pointedly cautioned young Scottish geologists not to be led away by the notion, that all conglomerates made up of crystalline pre-existing rocks represented the so-called old red conglomerate, and particularly referred to the coarse red conglomerate of Girvan in Ayrshire, which Prof. Nicol and himself had shown to be a part of the Lower Silurian series of the south of Scotland. Whilst, however, it is probable that the red conglomerate of the West Highlands, which is associated with the series of crystalline rocks, may be also of Lower Palæozoic age, it is clear that even on that account the stupendous masses of red sandstone which constitute the mountains of Applecross and Gareloch are unquestionably of a younger date. Positive proof of this was formerly given by Prof. Sedgwick and himself from unconformable junctions of the two classes of rock in the West Highlands at Ullapool, and on the eastern coasts also, where the oldest conglomerate and sandstone of the Old Red or Devonian age of Caithness, clasps round the quartzose and micaceous rocks of the Scarabin Hills, and is made up of the materials derived from those crystalline rocks 'which are contiguous to it. He then expressed his firm conviction, that, from the immense length of time which must have passed in its accumulation, the vast deposits called the Old Red Sandstone were the full and entire equivalents of the Devonian rocks of the south-west of England, and of the Rhenish provinces, and of large portions of other parts of Germany, as well as of France, Spain, and other countries. He strongly insisted on the fact, that in Russia, where he had traced such a very extensive range of rocks of this age, regularly interpolated between the Silurian and Carboniferous systems, there occurred a mixture of the same species of fossil fishes (Asterolepis, Dendrodus, Glyptosteus, Bothriolepis, Holoptychius, Cricodus, Plericthys, &c.) which prevail in the north of Scotland, with the shells which characterize the formation in the slates and calcareous type which it assumes in Devonshire. He then announced that, in addition to the fossils previously elaborated and described by Mr. Hugh Miller and other authors, a number of plants had recently been discovered, chiefly by Mr. C. Peach, of Wick, but also

by Mr. J. Miller and Mr. Dick, of Thurso, in the very heart of the Caithness flagstones-the great fossil Piscaria of the series. Of these plants, the large number of which Mr. Peach had submitted to him seemed to be of terrestrial origin, he hoped to obtain an account at a future period from Dr. Joseph Hooker, whom he had requested to write a decade upon them in the Memoirs of the Geological Survey of the British Isles.' The importance of correctly determining the character of these plants will be at once seen when it is considered that, with the exception of the minute and rare vegetable forms detected by the author in the uppermost Silurian rocks, which form a passage into the Devonian rocks or Old Red Sandstone, these Caithness fossils are probably the oldest known and clearly recognizable land plants; it being believed that the fossil vegetables hitherto found in the so-called Old Red, chiefly occur in the upper meshes of the system.

Such are certain plants discovered by Dr. Fleming and others in Shetland and Orkney, by the geological surveyors in Ireland; and such is the position of the very remarkable and beautiful Flora, detected by Mr. Richter of Sahlfield, in Germany, and which he alluded to last year, as being under the description of M. Unger, the celebrated fossil botanist of Gratz. The singular plant, however, formerly described by Mr. Hugh Miller as occurring in the Cromarty strata, must be considered to be of quite as old a date as the Caithness plants.

In recapitulating, Sir Roderick called special attention to the system of the older crystalline or metamorphic rocks, and expressed his conviction that the same series was several times repeated in the contigu ous tracts of Sutherland and Ross by great heaves of the masses,— such breaks being marked by the chief lochs or friths. He also dwelt on the very remarkable fact, that in these two northern counties there was an apparent symmetrical succession from older to younger masses in proceeding from the west to the east coast. Even the physical watershed of one portion of the region, as seen in the steep precipices of the Balloch of Kintail, only four miles distant from the western sult water of Loch Duich, indicating no anticlinal; the flagstones of gneissose rocks plunging rapidly to the east-south-east, a feature which was as forcibly presented in many places to the recent observation of Prof. Nicol and the author as it was to the latter and his former associate Prof. Sedgwick. Where these ancient rocks are developed in the more southern portions of the Highlands, and where they usually still preserve the same general strike from northeast to southwest as far north-north-east to south-south-west, their dips are, however, frequently anticlinal, owing to the powerful intrusion of massive igneous eruptive rocks: so that from Fort William or Ben Nevis southwards we have first in the porphyry of that mountain, and afterwards in the porphyries and syenites of Glencoe or the granite of Ben Cruachan, as well as in other points still farther south, great centres of disturbance by which the same series of quartzose, micaceous, and chloritic rocks with limestones, and in which clay slate more prevails than in the north, is repeated in vast undulations, some of which dip to the west-north-west and others to the east-south-east. One of the most southern of these anticlinals may be seen in the centre of Loch Eck, where the masses dip off to Strachur and Inverary on the northwest, and to the Clyde on the southeast.

In conclusion, the author enforced his view of the posteriority of the Old Red Sandstone to all such crystalline rocks by showing (as indeed Prof. Sedgwick and himself had done many years ago) that the coarse conglomerates of the Old Red Sandstone series, not only wrapped round those ancient rocks, but were absolutely made up of their fragments, and are seen in many places distinctly to overlie them, as at Loch Ewe, Gairloch, Applecross, &c. He further adverted to the great diversity of the strike and dip of the two classes of rock and of their entire unconformity to each other, of which he cited an instructive example at the head of Loch Keeshorn, where the lofty massive mountains of the Old Red Sandstone of Applecross, the beds of which had a steady, slight inclination of 10° or 12° to the northwest, whilst the low flanking and conterminous primary limestones, quartzites, mica schists and gneissose rocks extending from Keeshorn to Loch Carron plunge rapidly to the east-south-east. In short, whilst the limestone of Durness in Sutherland (identical in all its mineral characters and associations with quarzites with that of Keeshorn in Ross) is of very remote antiquity, and is probably, from its fossils of Lower Silurian age, the base of the Old Red Sandstone, forms a great belt composed of the regenerated materials of such older rocks, and distinctly overlies in a transgressive position the pre-existing crystalline rocks on the west, north, and east coasts of the Highlands. Referring in conclusion to the labors of Mr. Page, who had been zealously endeavoring to bring the Scottish Palæozoic classification into accordance with that of Eng land, the author remarked, that, in respect to the position of the English "Tilestones" there existed no sort of ambiguity. These "tilestones" constitute a thin zone which exhibits in many places a mineral transition for the Upper Silurian rocks into the base of the Old Red or Devonian series, and in which we found one species of a fossil fish which occurs in unequivocal Old Red Sandstone, thin shells which range through the Ludlow rocks. They also contain forms of a remarkable genus of Crustaceans, the Pterygotus, which is known in the Arbroath paving-stones of Forfar. If, indeed, the Scotch grey paving. stones should prove to be the true representatives of the English tilestones (the species of Pterygotus of each being identical), and that it be truly shown that the great conglomerate on the flanks of the Grampians underlies such Arbroath flagstones, then it will probably follow that a great coarse angular conglomerate of the Highlands, or at least part of it, represent in time some portion of the Upper Silurian rocks. With his present amount of knowledge, however, the geologist must believe that in this part of the Scottish Palæozoic succession there is a great hiatus, since no suite of organic remains hitherto discovered has shown the presence of the Ludlow and Wenlock or Upper Silurian rocks, as exhibited in England, Sweden, Norway, Bohemia, and North America.

3. Description of the Mineralogical Cabinet of the Garden of Plants at Paris; by M. J.-A. HUGARD, Assistant to the Professor of Mineralogy. 12mo, pp. 190. Paris, 1855.-This admirable guide to the mineralogical museum of France, deserves to be made known to the culti vators of mineralogy who never expect to make use of it in examining the collection itself, for which it was expressly prepared, inasmuch as