Cumulate apatite crystals with infilled tube-like cavities parallel to the c-axis are described from a layered gabbro intrusion in Northern Norway. These are considered to be skeletal crystals produced by rapid growth in the supercooled roof zone of the magma chamber. At least two stages of growth are suggested on the basis of the morphology of the apatites. The interiors of the crystals contain phases representing the trapped magma or the cumulus mineral phase within which they are enclosed. Recirculation of the apatite primocrysts by convection currents is indicated by the interrupted form of some of the tubes.

The reference of Isograptus manubriatus (T. S. Hall) to the genus Maeandrograptus Moberg by Skevington (1968) is argued to be invalid. A new genus, Pseudisograptus has been introduced to which the manubriate isograptids I. manubriatus, I. hastatus, and I. dumosus are referred.

Rb–Sr whole-rock isochron ages from shale horizons in the Late Pre-Cambrian tillite succession in Varangerfjord, Northern Norway, are presented. Although data from the Stappogiedde Formation, which overlies the tillite horizons, give a Caledonian, metamorphic age of 530±50 m.y., ages obtained from shales occurring between and below the tillites are believed to represent the approximate times of deposition of the sediments. An age of 810±90 m.y. for the Tanafjord Group enables this group to be correlated with the Upper Torridonian and the age of 668±23 m.y. for the Nyborg Formation, which is taken as the age of the Varanger Ice Age, allows a tentative correlation to be made with the Egan and Marinoan Glaciation in Australia.

Examination of rocky coastal profiles in Australia and Europe suggests that two major and genetically distinct types of erosional surface should be recognized, one of these being the shore platform, whether sloping or horizontal, smooth or rough, which is best developed on promontories and terminates in a low-tide cliff, the other being the wave ramp, often exposed in bays, which slopes gradually down from about high water level to merge with the submarine slope near-shore. A modified terminology for erosional surfaces on rocky coasts is proposed.

An agreed short text in English, French and German, presents a unified statement on those aspects of stratigraphy that require formal international acceptance. The statement is designed to avoid philosophical hazards and misunderstandings between the three language communities; it also harmonizes differences of three national traditions as far as is yet possible.

Stratigraphy is presented as an indivisible science dependent for its successful pursuit and synthesis on the application of numerous widely different methods.

The argument is presented in successive numbered steps to facilitate its critical discussion.

Consideration of the arctic configuration of the Caledonides leads to a distinction between eastern and western geosynclinal belts. The western belt, comprising the East Greenland, East Svalbard and southern Barents Sea Caledonides is postulated to continue northwards into the Lomonosov Ridge, whilst the western Spitsbergen Caledonides are thought to have originated as part of the North Greenland geosyncline which is also thought to continue northwards to form the western part of the Lomonosov Ridge. The eastern Caledonian geosynclinal belt comprising the Scandinavian Caledonides appears to swing eastwards to link with the Timan Chain and possibly the Urals.

The already postulated (‘Proto-Atlantic’) ocean concept is reviewed in the light of the Arctic Caledonides and named Iapetus. Faunal provincialism suggests that the ocean was in existence up to early Ordovician but had substantially closed by mid Ordovician times. Possible relics of the suture marking the closure of this ocean suggest that it lay to the west of the Arctic Scandinavian Caledonides trending NE to latitude 70° N and thence veered eastwards separating the southern Barents Sea Caledonides from those of Arctic Scandinavia, possibly connecting with the northern Uralian ocean. A previous branch of the ocean may have separated East Svalbard and East Greenland as an ocean-like trough. A further (pre-Arctic) ocean may have existed to the north of the North Greenland–Lomonosov Ridge geosynclines. This is named Pelagus.

The closure of these oceanic areas and the deformation of the bordering geosynclines delineates three principal continental plates, namely, Baltic, Greenland and Barents Plates. Their relative dominantly E–W motion up to Silurian times produced compression between the Greenland and both the Baltic and Barents plates but dextral transpression and transcurrence between the latter plates. In Late Silurian to Devonian times an increasing northward component controlled late Caledonian transpression and sinistral transcurrence between the Greenland plate and the combined Baltic and Barents plates.

Within the Tethyan Zone of Central West Nepal, the Nilgiri Limestone is the dominant unit. The significance of the separation of the Larjung Formation is questioned in the light of new outcrops examined, and the Nilgiri Sandstone is described. Recumbent fold structures are correlated between Annapurna, Nilgiri and Dhaulagiri. Between these mountains the Thakkhola graben faults are continued southwards, and estimates are made of the magnitude of their throws.

The present paper deals with the Lower Ordovician–Silurian rocks between Fördefjord and Sognefjord on the western coast of Norway. During the Caledonian orogeny this sequence was subjected to several phases of Silurian deformation, the first of which resulted in the formation of a large-scale anticline (the Stavfjord Anticline), which now occupies part of an overthrust unit. On the basis of ‘way-up’ criteria in the partly well-preserved Lower Ordovician pillow lavas it has been possible to determine with some confidence the geometry of the Stavfjord Anticline, its probable regional extension and the position of the axial plane trace. Arcuate deflections in the trend of this axial plane trace are a result of large-scale refolding, the later fold axes having WNW–ESE trends.

Curved and other variably oriented minor F1 folds with a common axial–planar cleavage are described from the Dalradian of the South-West Scottish Highlands. An explanation for the varying orientations is offered in terms of progressive deformation following the arguments of Flinn (1962) and Ramsay (1967).

The 18 curve from the 1390 m long ice core from Camp Century, Greenland, shows climatic changes that are easily correlated with known glacial and non-glacial events of North America and north Europe and are thus indirectly dated. With a known chronology, the glacial dynamic changes of the Greenland Ice Sheet can be calculated for the last 125,000 years. It is concluded that the dynamics of the Greenland Ice Sheet have changed drastically during this period and that these changes are directly related to major changes of climate and extension of the Wisconsin and Weichselian glaciations. Logarithmic time scales earlier applied to this curve must therefore be incorrect.

The Vesturhorn Intrusion of SE Iceland contains a tilted block consisting largely of size-graded, igneous-layered, eucritic gabbro, which is described in some detail. Size-graded, igneous layering is remarkably uncommon and at present there appear to be only two known occurrences. The physical properties of basalt magma suggest that most igneous layering is likely to form from currents moving by laminar flow. Considerations of flow in such a simple system do not satisfactorily account for the scarcity of this structure. It is suggested that size-graded, igneous layering may reflect the availability of convecting magmas containing crystals with appreciable proportions of different grain sizes of each mineral species. Such a grain size distribution, together with other features considered here, may indicate primocryst growth outside the chamber of deposition.

A small fauna of mammals, which includes Elephas antiquus, has been obtained from the Stretton Sand. This, the oldest member of the Pleistocene succession north of Moreton-in-Marsh, has previously been interpreted as glacial outwash from a Severn Valley source and usually ascribed to an early phase of the Wolstonian Glaciation. It is now ascribed to the Hoxnian interglacial, with its rare erratics of presumed Welsh provenance derived from erosion of an earlier Anglian glaciation.

From the distribution and orientation of final axial ratios of deformed elliptical pyrites and boudins, initial distributions are determined. A strain ellipse is then reconstructed using the shape factor grid. The long axis of the strain ellipsoid represents the trend of regional fold axis (the fold is of flexural slip type). The dimensional orientation (elongation) of the pyrites and the boudins is referred to the homogeneous strain components in the fold. Petrofabrics of the pyrite cubes indicate that they have a preferred orientation.

The distribution of Fe and Mg between coexisting garnet and biotite from andalusite-staurolite zone rocks of the Mt Lofty Ranges is briefly discussed. The average value of the corresponding distribution coefficient, and those of some related parameters, are compared with the values proposed by a number of authors as being characteristic of certain metamorphic grades. From these comparisons it is concluded that despite their occurrence in a terrain in which fibrolite commonly occurs, the rocks have probably only experienced P-T conditions corresponding to those of the andalusite phase field, and that fibrolite has formed under similar conditions.

The toolmark pattern on an erosional furrow from the Llandovery shelf sequence in the Welsh Borderland indicates that there was:— (i) local helical flow within the furrow similar to that found in sinuous alluvial streams and (ii) a moderately powerful current which moved towards the shore. Erosion by a shallow water turbidity current or storm surge tidal ebb flow therefore seems unlikely. A flood tidal current super-imposed on storm wave oscillatory disturbance of the sea-floor provides a possible mechanism.

Precambrian rocks throughout most of the southern part of the Bighorn Mountains, Wyoming, are dominated by a biotite-bearing plagioclase–quartz gneiss containing hornblende-rich or microcline-rich layers locally. Compositional and/or optical data are presented for plagioclase, biotite, and hornblende as well as optical and X-ray data for microcline and preliminary morphologic data for zircon in the gneiss. These data, supplemented by field and petrographic observations, suggest that the gneiss was formed under conditions of the low amphibolite facies, that late-occurring potash metasomatism accompanied the metamorphism, and that the gneiss was derived from a relatively chemically uniform parent rock.

The lacinia in Paraglossograptus Mu is shown to consist of four ladder-like networks which are independent of each other and have no direct connection with spinose thecal apertural processes. The lacinial networks are positioned at the corners of the quadrangular rhabdosome as in Paraglossograptus ? sp. of Whittington & Rickards, which is described here as Paraglossograptus proteus (Harris & Thomas). Paraglossograptus etheridgei (Harris, 1924), the important Ordovician zone fossil, together with P. typicalis Mu and P. latus Hsü, are considered junior synonyms of Reteograptus tentaculatus J. Hall, 1865. P. tentaculatus (J. Hall, 1865), is regarded here as the type species of Paraglossograptus Mu. Detailed comparisons are made between P. tentaculatus and the stratigraphically younger P. proteus (Harris & Thomas), and with Glossograptus holmi Bulman, a species in some ways intermediate between Paraglossograptus and Glossograptus Emmons.

The junction in Newlands Beck between the steeply dipping Skiddaw Slates striking N–S, and Borrowdale Volcanic rocks dipping gently to the SE is interpreted as an angular unconformity, and indicates the existence of pre-Borrowdale Volcanic folding. There is no cleavage associated with this folding, however, the ENE–WSW Caledonoid cleavage being the only one present, and this is common to both Skiddaw Slates and Borrowdale Volcanics.

It is pointed out, with a few examples, that metamorphic rock compositions can be significantly modified by the stable mineralogy that itself may provoke metasomatic movement, as distinct from externally actuated metasomatism.

A reconstruction of the tectonic history of part of the Benue Trough is made from a study of the marine transgressions and regressions in SE Nigeria. Two periods of deformation involving essentially the interaction of continental plates are suggested. The oceanic crust produced by crustal attenuation in the Benue rift is very minimal. Unstable tectonic conditions in the Benue Trough may have created conditions for the development of an evaporite sequence.