The development of an alkali pyroxene-bearing fades of granite at the contact of the Beinn an Dubhaich granite of Skye with Durness dolomites is associated with a skarn formation involving magmatic transfer of alumina. The significance of the processes at work in this and related examples is discussed.

A series of very wide (up to 15 km) raised shore platforms in the Scottish Hebrides are identified and described for the first time and are considered part of a high rock platform shoreline in the western isles of Scotland described by W. B. Wright in his classic Geological Magazine paper a century ago as a ‘preglacial’ feature. Subsequent interpretations suggesting that the platforms were produced during the Pleistocene are rejected here in favour of a speculative hypothesis that the features are part of the well-known strandflat that is extensively developed across large areas of the northern hemisphere. It is argued that the Scottish strandflat developed during the Pliocene and was later subjected to extensive Pleistocene glacial erosion such that only a few areas of platform have survived in the Scottish Inner Hebrides (ice-proximal) while they are well-preserved in the Outer Hebrides (ice-distal). Support for a Pliocene hypothesis is provided by the marine oxygen isotope record for this time interval which points to prolonged periods of relative sea level stability as would be required for the production of such wide features. This hypothesis for the formation of a Scottish strandflat not only provides an elegant explanation for the origin and age of the raised rock platform fragments that occur throughout the western isles of Scotland, but it may also have relevance for other coastal areas of the northern hemisphere (e.g. Norway, Greenland, Alaska) where the strandflat is a well-developed feature.

Some closed basins extending along the strike of soft rocks in the English and Bristol Channels were cut by sand moved by tidal currents.

The Adrano area covers approximately 150 km2 of the tower SW flanks of Mount Etna, Sicily. A wide selection of the rocks that occur on the volcano are represented in the area. Lavas of alkalic affinity form by far the greater proportion of the volcanics in the area, and comprise a trachybasaltic suite of lavas ranging from hawaiite through mugearite to benmoreite. There appears to be no overall progressive variation in the chemistry of these trachybasaltic lavas with time; rather that the parental magma has remained fairly constant in composition. Periodically, however, this parental magma has been able to differentiate into more evolved products. The chemical variation shown by the trachybasaltic lavas can be largely explained by crystal fractionation of augite, olivine, plagioclase and titanomagnetite at moderate to low pressures. Crystal fractionation, however, cannot explain the variation in the alkalis which is thought to be affected by volatile transfer.

Eight latest Eocene to earliest Miocene stratigraphic surfaces have been identified in petroleum well data from the Taranaki Basin, New Zealand. These surfaces define seven regional sedimentary packages, of variable thickness and lithofacies, forming a mixed siliciclastic–carbonate system. The evolving tectonic setting, particularly the initial development of the Australian–Pacific convergent margin, controlled geographic, stratigraphic and facies variability. This tectonic signal overprinted a regional transgressive trend that culminated in latest Oligocene times. The earliest influence of active compressional tectonics is reflected in the preservation of latest Eocene – Early Oligocene deepwater sediments in the northern Taranaki Basin. Thickness patterns for all mid Oligocene units onwards show a shift in sedimentation to the eastern Taranaki Basin, controlled by reverse movement on the Taranaki Fault System. This resulted in the deposition of a thick sedimentary wedge, initially of coarse clastic sediments, later carbonate dominated, in the foredeep close to the fault. In contrast, Oligocene active normal faulting in a small sub-basin in the south may represent the most northerly evidence for rifting in southern Zealandia, related to Emerald Basin formation. The Early Miocene period saw a return to clastic-dominated deposition, the onset of regional regression and the southward propagation of compressional tectonics.

Four stage names are erected within the southern part of the type area of the Llandovery Series, south-east of Llandovery, Carmarthenshire, Wales. They are Rhuddanian, to incorporate the existing Lower Llandovery; Idwian for the Middle Llandovery, and Fronian and Telychian for the Lower and Upper parts of the Upper Llandovery. Correlation with the sequence of graptolite zones is suggested.

The base of the Llandovery at Llandovery is poorly exposed and unfossiliferous, and detailed correlation with other areas may always remain uncertain. Thus the base of the Llandovery Series, and hence the base of the Silurian System, is defined in Lapworth's classic locality at Dobb's Linn, Moffat, Scotland, at the base of the zone of Glyptograptus persculptus.

The metamorphism of Pre-Cambrian dolerites in the Northwest Highlands is described and compared with that of basic rocks in the Southwest Highlands, Banffshire and other regions. The first products of metamorphism are not the same in every area. It is suggested that the trend of regional metamorphism differs according to the environment in which it took place, and that a sequence of changes established in one area cannot be used as a standard by which to judge the changes in other areas. In particular, rocks of high metamorphic grade have not invariably passed through stages characterized by low-grade minerals.

Thin, but laterally widespread, fallout ash tuff layers interbedded with complex fluviolacustrine successions of the Carboniferous–Permian late Variscan intermontane Saar–Nahe Basin in southwestern Germany provide important tephrostratigraphic markers in the purely continental depositional setting. The tuffs are rhyolitic to rhyodacitic and indicate geochemical affinities to Moldanubian Variscan S-type granitoids. The volcanic ashes are suggested to have been derived from the general region of the central and northern Black Forest (southwestern Germany) and the northern Vosges (eastern France) at 100–150 km distance south of the Saar–Nahe Basin. Six tuff beds from the Jeckenbach and Odernheim subformations (Meisenheim Formation, Glan Group) have been correlated within the basin over a distance of 50 km by mapping and whole-rock geochemical fingerprinting. In each subformation, three tuffs can be well distinguished using geochemical discriminant function analysis. Additional comparisons of trace and rare-earth element contents provide further criteria for the differentiation of individual tuff beds. These discriminations show that the tuffs have unique chemical fingerprints, probably reflecting differences in the original composition of the parent volcanic tephra. Thus, chemical differences between the tephrostratigraphic markers are geologically significant and provide a powerful tool for establishing tuff layer identification and correlation within the complex sedimentary sequence of the Saar–Nahe Basin. They also provide clues to the tectonomagmatic settings of the source volcanoes.

The paper describes those features of the Scardroy Lewisian mass, a sheet-like body of basement rocks thrust into the younger Moine Series, which suggest that this mass was driven up through a thickness of several kilometres of Moinian rocks and inserted as a narrow wedge within the Moine succession, never penetrating the highest members of that succession. The relations of the Scardroy mass, to which most of the Lewisian outcrops of central Ross-shire belong, differ from those of the more westerly outcrops of Lewisian in the region of Glenelg where the basement rocks have been shown by the work of Clough and others to represent wedges lying between tightly-compressed synclines of Moinian rocks which form a more or less autochthonous cover. The connection between the two types of structure is discussed.

The Forland Complex of Prins Karls Forland has been subjected to mid-Palaeozoic greenschist facies metamorphism and polyphase deformation. Metamorphism was initiated prior to D1 deformation and gave rise to a parallelism of stratigraphic and metamorphic reaction surfaces. D1 gave rise to imbricately thrust, southwest-directed fold nappes which have not noticeably disturbed the isograd surfaces. D2, interpreted as belonging to the mid-Cenozoic West Spitsbergen Orogeny (WSO) which was coaxial but not coplanar with D1, produced crenulation folds and pressure solution cleavages and some thrusting. D3 structures are related to the formation of the Prins Karls Forland–Forlandsundet–Oscar II horst and graben system which is a late expression of the WSO. The rejuvenation of the Prins Karls Forland horst along NNW–SSE faults, the large scale E–W flexures and ENE–WSW faults in the Forland Complex and Tertiary graben deposits are assigned to D3.

Natural pyroxene spinifex-textured rocks, free of olivine, may have MgO contents as high as 15%. If these rocks are allowed to crystallize in the laboratory under equilibrium conditions, olivine is the liquidus phase at 1350°C and pyroxene does not appear until the temperature has fallen to 1180°C. A similar problem is encountered in high MgO komatiites. If spinifex-textured and aphyric komatiites from Munro Township are plotted on an MgO-CaO-Al2O3 diagram, olivine control is evident until the MgO content of the melt falls to 15%. At this point the liquid trend moves away from the CaO-MgO boundary, indicating the crystallization of pyroxene. If a high MgO komatiite is crystallized in the laboratory under equilibrium conditions, pyroxene does not appear until the MgO content of the liquid reaches 9%. It is suggested that experimental and natural systems behave differently because pyroxene has crystallized metastably in the natural system under conditions of extreme supercooling. The early metastable crystallization of pyroxene can only affect the liquid trend if the spinifex zone contains a cumulate component.

Newly discovered Tremadoc rocks in South Wales are described from outcrops south of Carmarthen. The faunas suggest that both the Clonograptus tenellus and Shumardia pusilla Zones are represented, together with possible higher Tremadoc strata.

The muscle systems of Lingula, Discinisca, and Crania have been described in considerable detail and in general with progressive accuracy by numerous workers since the time of Cuvier and Owen, and the best and apparently most recent accounts are to be found in two works by Blochmann (1892, 1900). But I am not aware that there exist any diagrams of these systems readily accessible to the palaeontologist; Fischer and Oehlert (1887) give some figures adapted from Joubin (1886), but these are in some respects inaccurate and Blochmann's work, other than on Crania, has not apparently found its way into palaeontological literature. The purpose of the present note is little more than to provide diagrams of the shell muscles of the above-mentioned living genera, and to attempt certain palaeontological restorations. I have had the opportunity of verifying the structures in spirit Lingula and to some extent in Crania, thanks to the kindness of Dr. C. F. A. Pantin.

Within the Scottish Caledonides, the Glen Scaddle Metagabbro was intruded into the Moine Supergroup of the Northern Highland Terrane after Grampian D2 folding and prior to regional D3 and D4 upright folding and amphibolite-facies metamorphism. A U–Pb zircon age of 426 ± 3 Ma obtained from the metagabbro is interpreted to date emplacement. D3–D4 folding is constrained to have occurred during the Scandian orogenic event. In contrast, polyphase folding and regional metamorphism of the Dalradian Supergroup southeast of the Great Glen Fault is entirely Grampian. These differences are consistent with published tectonic models that invoke a minimum of 700 km of post-Scandian sinistral displacements across the Great Glen Fault to juxtapose the Grampian and Northern Highland terranes.

Gravity measurements in Durham and Northumberland in the region of the Alston Block are described, and their reduction as well as the accuracy of the results discussed. It is shown that the results between and near Newcastle and Durham are fully consistent with the conception of a horst, uplifted between the Ninety Fathom Dyke and the Butterknowle Fault. The observations along the valley of the East Allen, however, require an entirely different explanation. It is concluded that a closed area of negative anomalies occurs, centred near Wear Head. This is interpreted as due to a granite intrusion not yet exposed by denudation. The mineralization of the area is discussed and it is shown that it supports the foregoing interpretation.

Schaubcylindrichnus, a distinctive sheaf of arcuate, well lined, congruent dwelling tubes, although poorly known in general, is a good indicator of shoreface depositional settings for many Cretaceous rocks of the United States. Until recently, in fact, it was known only from those rocks; but it has now been recognized in Tertiary rocks of Taiwan, possibly in slightly more distal depositional settings. In addition to its distinctive morphological and environmental significance, the ichnogenus also may have substantial biostratigraphical significance. Further reconnaissance is needed to confirm these seemingly unique distributions, that is, to help explain why the trace fossil so far seems to be restricted to certain Cretaceous rocks in North America and certain Tertiary rocks in Asia.

The confusion that has arisen over the interpretation of the D2—D3 boundary is analysed and a new definitive section of the Upper D Beds is given.

For many years composite minor intrusions, both sills and dykes, have been known from various parts of the world and most petrologists must have speculated as to the probable effect produced in the event of such composite intrusions having reached the surface in the form of an effusion. For obvious reasons it has not been found possible to trace a composite dyke upwards into a lava flow. However, during the revision of 1 inch Sheet 30 (Renfrewshire) for the Geological Survey, the author encountered, in the neighbourhood of Inverkip, a small village on the Firth of Clyde south of Greenock, certain peculiar lava flows which are believed to represent the effusive equivalents of composite minor intrusions. These “composite lavas”, which form the main subject of the present paper, are of Lower Carboniferous age (Calciferous Sandstone Series) and occur interbedded among the more normal flows towards the base of the volcanic group. Two distinct rock varieties, one highly porphyritic, with large phenocrysts (up to 1·5 cms. long) of basic plagioclase, and the other non-porphyritic, are associated within the same flow. The porphyritic type always forms the upper part of the flow and overlies the non-porphyritic; the junction shows unmistakable evidence that both were in a fluid state along their mutual contact at the time of emplacement.

Values for δ13C and δ18O obtained from molar samples from three individuals pertaining to Glyptotherium sp. from Cedral (San Luis Potosí, México) are provided and are utilized to infer general aspects of glyptodont diet and habitat. On average this animal showed a C3/C4 mixed diet, with a high consumption of C4 plants. Comparisons of the δ13CVPDB and δ18OVPDB values for glyptodonts with horses, mastodons, mammoths and tapirs from the same locality show that glyptodonts from Cedral lived in an open habitat.