Plant-remains have long been known to occur at a horizon near the top of the Lower Old Red Sandstone of Perthshire, far above the volcanic horizon represented in the Ochil Hills. Evans, in the Handbook of the Geology of Great Britain (1929), speaks of these Perthshire plants as occurring “near the summit of the Strathmore Sandstones”; but it is as well to remember that Evans' definition of Strathmore Sandstones is very wide, including all “beds above the Cairnconnan Grits” of Forfar. Hickling (1908) and Campbell (1913) refer to the Strathmore Beds or Group in a much more restricted sense. For them the term is a synonym for Edzell Shales, the uppermost of four divisions united by Evans as Strathmore Sandstones. On account of this uncertainty we prefer, for the present, not to employ the term Strathmore with any stratigraphical significance.

Four new species of petrified seeds are described:

1. 1. Eccroustosperma langtonense gen. et sp. nov.—a curved platyspermic seed with two apical lobes of the integument and a rough sclerotesta when mature.

2. 2. Hydrasperma tenuis gen. et sp. nov.—a small slender seed with 8–10 free apical lobes and longitudinal external ridges.

3. 3. Stamnostoma bifrons sp. nov.—a barrel-shaped seed with a nucellar apex and micropyle intermediate in form between Stamnostoma huttonense and Sphcerostoma ovale.

4. 4. Dolichosperma sexangulatum gen. et sp. nov.—a relatively long narrow radiospermic seed with a dense sixangled integument open above and without tentacles or micropyle. The salpinx was probably funnel-shaped.

All four species are assigned to the Lagenostomales.

During her famous circumnavigation of the world, H.M.S. Challenger left the Cape of Good Hope on the 17th December 1873, and, proceeding in a south-easterly direction, visited in succession Prince Edward and Marion Islands, the Crozet Islands, Kerguelen Island, and Heard Island. From Heard Island the Expedition sailed southward, and on the 16th February 1874 passed ten miles beyond the Antarctic Circle in longitude 78° 22′ E., the ship being at this time surrounded by a large number of huge tabular icebergs, some of them four miles in length, and all with perpendicular sides rising about 200 feet above the sea-level. From this most southerly point the Challenger took a north-easterly course towards Melbourne in Australia, where she arrived on the 17th March 1874.

The Silurian arthropod Bembicosoma pomphicus Laurie, 1899 is re-studied in relation to other Palaeozoic chelicerate taxa. All three known specimens of Bembicosoma originate from the Silurian (late Llandovery) Eurypterid Bed of the Gutterford Burn Flagstones, Reservoir Formation, Pentland Hills, Scotland. Bembicosoma is removed from its previous tentative assignment to Eurypterida and re-assigned to Xiphosura. A morphological reconstruction of this taxon is presented for the first time. This work continues a reappraisal of the systematics of a number of taxa that belong within the synziphosurines, a loose grouping of early Palaeozoic chelicerate arthropods aligned with the Xiphosura (horseshoe crabs), but which have been mistakenly identified as eurypterids in the past. Bembicosoma is significant as it is one of the earliest known synziphosurines.

Tristychius arcuatus, from the late Viséan of Scotland, is known from numerous ironstone nodule-encased specimens. These are reinvestigated using computerised tomography (CT) scanning and 3-D digital reconstruction methods. CT scans of the neurocranium (braincase) corroborate many features of the existing reconstruction, but also reveal new details of the gross proportions, the external morphology and, for the first time, features of the internal morphology, including the otic skeletal labyrinth. The unusual position of the articulation for the palatoquadrate on the ventral surface of the postorbital process is confirmed, but the area for the hyoid articulation is relocated posteriorly and the configuration of nerve foramina within the orbit is changed. A preliminary phylogenetic hypothesis is offered, suggesting a place for Tristychius within a sequence of early branching events in the elasmobranch lineage. In this, Tristychius is not resolved as a hybodontid, but is instead a stem elasmobranch possibly related to genera such as Acronemus, and exemplifying anatomical conditions close to the base of the Euselachii. As such, the neurocranium of Tristychius offers important insight into a defining feature of these early members of the anatomically advanced elasmobranchs: the origin of specialised phonoreception.

The area lies within a ∼15 km-wide compartment of polyphase-deformed Dalradian (Neoproterozoic) rocks, bounded by the NE-trending Tyndrum and Ericht–Laidon transcurrent faults. Sinistral movement on these faults caused a periclinal structure, the Orchy Dome, to develop from flat-lying Dalradian rocks. This dome controlled the spatial distribution of lamprophyre intrusions and explosion breccia pipes, before being cross-cut by a network of near-vertical faults. Some of these faults are host to giant, segmented, quartz-breccia veins up to 5 km long and 19 m thick, formed by cyclic injection of over-pressured Si-rich fluid into newly-formed faults. The quartz-breccia bodies consist of a plexus of quartz veins with cockade and vuggy textures, indicative of open-space, high-level crystallisation. The faults comprise a NE-trending set of mineralised veins, including the Cononish Au–Ag deposit, and two pairs of conjugate [NW- and NE-trending] and [NNW- and NNE-trending], generally non-mineralised, faults. Their geometry is that predicted by the Coulomb model for Riedel R and R′ shear fractures, modified by variations in pore fluid pressure. They were active c. 430–425 Ma ago, coincident with emplacement of the Lochaber Batholith, whose buried extension, together with the mantle, probably provided the bulk of the fluid needed to form the veins.

Development of shale gas by hydraulic fracturing (‘fracking’) is opposed by campaigners who propose (inter alia) that freshwater aquifers could be polluted by upward migration of fractures and any fluids they contain. Prima facie hydrogeological analysis of this proposition has been undertaken. For it to occur, two conditions must be satisfied:

1. (i) sufficient hydraulic interconnection (i.e., a continuous permeable pathway); and

2. (ii) a sustained driving head, oriented upwards.

With regard to (i), shale gas developers have a major vested interest in avoiding creating such hydraulic connection, as it would result in uneconomically excessive amounts of water needing to be pumped from their wells to achieve gas production. In relation to (ii), nominal upward hydraulic gradients will typically only be developed during fracking for periods of a few hours, which is far too brief to achieve solute transport over vertical intervals of one or more kilometres; thereafter, depressurisation of wells to allow gas to flow will result in downward hydraulic gradients being maintained for many years. The proposition is therefore found to be unsupportable. Albeit for contrasting motivations, developers and environmental guardians turn out to have a strong common interest in avoiding inter-connection to aquifers.

A powerful illustration of the potential long-term effects of fracking is provided by the hydrogeological history of underground coal mining in the UK. Where large-scale mining proceeded from the surface downwards, major hydraulic inter-connection of shallow and deep zones resulted in widespread water pollution. However, where new mines were developed at depth without connections to shallow old workings (as in the Selby Coalfield, Yorkshire), complete hydraulic isolation from the near-surface hydrogeological environment was successfully maintained. This was despite far greater stratal disruption and induced seismicity than shale gas fracking could ever produce. The lesson is clear: without hydrogeological connectivity to shallow aquifers, shale gas fracking per se cannot contaminate shallow ground water.

The Murotomisaki Gabbroic Intrusion is a sill-like layered gabbro emplaced in sedimentary strata of Tertiary age in southwest Japan. The zoning (including resorption structures) and the compositional variations of plagioclase from throughout the intrusion were studied, and it was found that the zoning pattern may be classified into four types, which may well correlated with the hosting rock types, the mode of occurrences and their stratigraphic positions in the intrusion. The plagioclase zoning was successfully decoded, and the sequence of events that took place during the magmatic differentiation was deduced and further interpreted in the context of a stratified basal boundary layer slowly ascending in a solidifying magma body. It was shown that various layered structures – modal layering, podiform gabbroic pegmatites and anorthositic layers – observed in the Murotomisaki Gabbro were formed within the moving basal boundary layer by flushing of H2O-rich fluid and fractionated silicate melts from below. By the fluxing of hydrous fluids, plagioclase crystals preferentially dissolved and then melt fraction increased in the basal boundary layer. Under these circumstances, plagioclase-rich fractionated melts diapirically segregated from the crystal pile. Calcic plagioclases, which are out of equilibrium in the central part of the intrusion, may have originated from the basal boundary layer in this manner.

The western end of the Galway granite batholith demonstrates the importance of stoping as a granite emplacement process, which is currently controversial, and also of space generation by uplift of the centre of a ring complex. The granite rings are shown (with a coloured 1:25 000 geological map) to be consanguineous, near coeval, and older than the 407–410 Ma late molybdenite mineralisation. A newly-recognised Mace–Ards granite, around and injected by the Aplitic Murvey-type granite of the ring core (both lacking hornblende and titanite), has biotite–muscovite–cordierite orbs and sulphide–granite orbs, showing separation of immiscible hydrous and sulphide fluids from the late magma which, with vugs, indicates a low pressure, near-roof site. The outer ring of the Errisbeg Townland granite (ETG, the main batholith granite with K-feldspar phenocrysts), was emplaced by progressive outward stoping of the country rock metagabbro, as shown by mapping, and by chemical fractionation of feldspars, biotites and bulk rocks, to the marginal, dry, fine-grained aphyric, in part garnetiferous, highly fractionated, siliceous Murvey granite. Stoping ceased when, after previously invading dense metagabbro, the outer ring complex reached the low-density Roundstone granite, which is shown for the first time to be older than the Galway batholith. This arresting of the batholith intrusion shows that stoping was such a significant process that emplacement ceased when stoping became impossible. The inside edge of the ETG grades into the slightly later, intrusive, aphyric Carna granite, which shows inward fractionation to the wet magma of the Mace–Ards granite. The ring complex core was injected by highly fractionated, dry, Aplitic Murvey-type granite, intensely hydrothermally altered by late magmatic water. The radially outward dipping, inclined igneous layering in the ETG shows that the original ETG centre was pushed upwards by the intruded Carna granite and eroded away. The Galway granite and its nearby magmatism matches the low Ba and Sr, high Th and Rb, Scottish Cairngorm Suite and similarly has few appinitic rocks associated with it. Magmatism extended over >45 Myr from ∼425 Ma to 380 Ma. It originated by slab breakoff and consequent rise of the asthenosphere, causing deep crustal melting.

The mosses of Kincardine and Flanders are situated in that extensive plain or carse which begins at Borrowstounness, on the south side of the Frith of Forth, and a little above Eastern Kincardine, on the north side. It stretches along both sides, first of the Frith, and afterwards of the river Forth, as far as Cardross, about twenty-two miles west of the point where it begins. The breadth of this plain, or carse, at Falkirk, where it is widest,is about seven miles, including what is occupied by the Frith.

The discovery in 1966 of Ni sulphide deposits at Kambalda, Western Australia resulted from the interpretation of siliceous limonitic material containing up to 1·0% Ni and 0·3% Cu as the gossanous expression of Ni sulphides. In many cases analysis for Ni, Cu, Zn, Co, Cr, Mn and Pb will distinguish Ni–Cu gossans from other oxidised sulphide assemblages and pseudo-gossans. However, most geochemical classification schemes cannot always distinguish strongly silicified or sulphide-poor Ni gossans from Fe sulphide gossans enriched in Ni and Cu or from some nickeliferous oxidised and lateritic products which have no sulphide source. Ambiguous cases may be resolved by analysis for Pd and Ir but this method is expensive and requires very sophisticated analytical techniques.

The use of reflected light microscopy to examine microtextures preserved in the surface gossans from a supergene pyrite-violarite-marcasite sulphide assemblage has allowed the refinement of geochemical classification schemes. The preservation of supergene zone textures by pseudomorphous Si–Fe replacement often permits the original sulphide proportions and Ni–Cu grade to be reliably assessed. Relict microtextures are usually preserved, even in pale coloured, highly siliceous gossans containing less than 0·01% Ni.

The Polychæte family Scalibregmidæ comprises seven genera, the limits and interrelationships of which are, however, still imperfectly known. The present paper results from a detailed study of one of these genera, a new species of which is described, chiefly from a specimen collected in Scotia Bay, South Orkneys, and entrusted to me for examination by Dr W. S. Bruce.

Description of the Specimen Collected in Scotia Bay, South Orkneys.: This specimen, the only Scalibregmid found by the Scottish National Antarctic Expedition, was dredged on a stony bottom in ten fathoms at Station 325, in Scotia Bay, South Orkneys (lat. 60° 43′ 42″ S.; long. 44° 38′ 33″ W.), in August 1903.

The worm, which is yellowish brown in colour (in alcohol), is 19 mm. long. The anterior portion is broad; the maximum breadth, 3 mm., is reached about the level of the 10th segment; from this region the worm tapers gradually to the anal segment. The dorsal surface of the worm is strongly convex; the ventral surface is flattened, and there is a well-marked depression which extends along the mid-ventral line from the 2nd chætiferous segment almost to the anus.

In the early part of 1900 I received from J. H. Ponsonby, Esq., a small collection of land molluses from N.W. Borneo, with a request that I would investigate and report upon the same. This collection, the property of the Sarawak Museum, proved, on examination, to contain examples of two new genera (Wiegmannia and Isselentia) of great interest. In the case of the former genus there were only two specimens, each belonging to a different species; and as more material was very desirable, Mr Ponsonby very kindly invited the authorities of the Museum to send over, if possible, a further collection. This, in due course, arrived, but contained duplicates of Isselentia only, the remaining specimens being all new species, excepting one, which proved to be the Damayantia dilecta of Issel, which, I believe, has not previously been found since described in 1874.

Sanders and Johnston (1989) have recently suggested that the Stac Fada Member is a fluidised peperite rather than a volcanic mudflow as thought by Lawson (1972) and the writer (1988). I agree that the volcanic mudflow hypothesis is flawed, but give reasons below for thinking that the new hypothesis is also untenable.

The Lebowa Granite Suite of the Bushveld Complex is a large, 2054 Ma old, A-type batholith, characterised by numerous relatively small magmato-hydrothermal, polymetallic ore deposits. The mineralisation is represented by a three-stage paragenetic sequence: early magmatic Sn-W-Mo-F ores (600°C > T > 400°C), followed by a Cu-Pb-Zn-As-Ag-Au paragenesis (400°C > T > 200°C) and then late-stage Fe-F-U mineralisation (< 200°C). The first stage of mineralisation (typified by the endogranitic Zaaiplaats tin deposit) is related to incompatible trace element concentration during crystal fractionation and subsequent fluid saturation of the magma. Evolution of the late magmatic fluids as they were channelled along fractures, as well as mingling with externally derived connate or meteoric fluids, resulted in the deposition of the second stage of mineralisation (typified by the fracture-related, endogranitic Spoedwel and Albert deposits and the exogranitic, sediment-hosted Rooiberg mine) which is dominated by polymetallic sulphide ores. As the externally derived fluid component became progressively more dominant, oxidation of the polymetallic sulphide assemblage and precipitation of hematite, pitchblende and fluorite occurred generally along the same fracture systems that hosted the earlier sulphide paragenesis.

Small hydrothermal zircons trapped along quartz growth zones from the Spoedwel deposit yield a U-Pb concordia age of 1957 ± 15 Ma. Whole-rock Rb-Sr age determinations from the Lebowa Granite Suite fall in the range 1790 ± 114 Ma to 1604 ± 70 Ma and are interpreted to reflect alkali element mobility and isotopic resetting during exhumation of the Bushveld granite. In contrast to thermal modelling which indicates that hydrothermal activity should have ceased within 4 my of emplacement, isotopic evidence suggests that mineralisation was long-lived, but episodic, and that fluid flow events were linked to major periods of Palaeo- and Mesoproterozoic orogenic activity along the margins of the Kaapvaal Craton. During these orogenic episodes, fluid flow was enhanced by tectonically induced fluid over-pressuring and/or exhumation of the Bushveld Complex.

I was led to the following investigations while seeking an elementary, and at the same time instructive, application of Hamilton's General Method in Optics. They were completed in all but a few of their numerical details before I met with the remarkable paper by Wollaston, in which the subject of multiple atmospheric images seems first to have been treated by a sound physical method. Wollaston's experiment with a long bar of iron raised to a high temperature suggests undoubtedly the true explanation of at least many of the curious phenomena seen by Vince, Scoresby, and others. But he seems to have thought that sufficient temperature-differences for the natural production of the phenomena could not exist in the atmosphere; and thus the latter part of his paper, in which he tries to explain them by the agency of aqueous vapour, presents a singular contrast to the strength and correctness of the earlier part. A good deal of what follows is implied, if not directly stated, in Wollaston's paper; but I think there is sufficient novelty in what remains to justify my bringing it before the Society.

The deposits of the Devonian period over a large area in the interior of North America to the south of the great lakes are known to be wholly of marine type and to have continued those of the Silurian period. They were formed in a great gulf open to the south. Along the western border of this gulf shore-deposits and, during Upper Devonian times, deposits of Old Red Sandstone type were accumulated, while in the middle of the gulf the resulting rocks were limestones and shales. In Ohio, following on a narrow band of what is regarded as Oriskany Sandstone (Lower Devonian), the Corniferous limestone and some local representatives of the Hamilton formation represent the Middle Devonian. Above this comes a great mass of black shale, which here represents the whole Upper Devonian and may continue up into black shales of the Lower Carboniferous. A black shale at the base of the Upper Devonian rocks has an extensive range in the central region of North America, being represented by the Huron shale in Canada and the Genessee shale in New York. Drifted land plants from the coast of the gulf, or from islands in it, have been found in the black shale and also in the underlying Corniferous limestone, and some other fossils are commonly spoken of as Algæ but have afforded little or no botanical information.

The collection of Scotia corals is naturally small, since the main work of the Scottish National Antarctic Expedition was in high Southern latitudes, but, during the outward and homeward journeys of the Scotia, collections were made, when opportunity presented itself.

The species are interesting distributionally, but their soft parts are largely decayed. There are five species, of which one is a known species; three dead masses, generically determinable; and the last, a new species, which may in future prove of even greater interest than at the present time.

In my former paper on the subject, I selected the following problem:—

From a given square, one quarter is cut off, to divide the remaining gnomon into four such parts that they shall be capable of forming a square.

The gnomon is, I assume, incapable of being formed into a square by being cut into three parts, and consequently the number of different ways in which it can be so formed, by cutting it into four parts, must be very limited. But, to show the fertility of the method of superposition, I exhibited the solution of the problem in twelve different manners. Many of these, no doubt, have much that is in common, whilst, on the other hand, some (such as the 12th) differ in every feature from the rest. I had thoughts of following up my plea for the study of the old geometry, by exhibiting the solutions of the 47th proposition of Euclid's first book in their beautiful variety. I have indeed temptation to do so. The modification which I gave of the demonstration of this proposition in the notes to my edition of Playfair's Geometry (edition 1846, p. 273), has had the honour of being exhibited in two different mechanical forms. The first by two rotations without sliding, whereby the two squares on the sides, when placed together, are converted into the square on the hypothenuse; the second, by two transpositions (slidings) without rotation, whereby the same change is effected The former is obvious enough, and could have escaped nobody. The latter is described by Professor De-Morgan in the “Quarterly Journal of Mathematics,” vol. i. p. 236.

Gemünden is situated in Rhenish Prussia, about eighteen miles to the west and slightly also to the south of Bingen, in the district known as the “Hunsrück,” and the rock in which the fishes to be described in this memoir occur is called the “Hunsrück Slates.”

These Hunsrück slates belong to the Lower Devonian of the Rhenish area, and the position assigned to them by German geologists is as follows:—

The above table is quoted from Kayser and Lake's Text-book of Comparative Geology, as is also the following brief statement regarding the Hunsrück slates themselves.