The Blue Anchor Formation of the Upper Trias in south-west Britain is divided into two members. The lower (Rydon Member) was deposited in an evaporitic lacustrine environment whilst the upper (Williton Member) was deposited in a shallow marine environment and represents the initial marine transgression into south-west Britain late in the Triassic Period. Sedimentological and clay mineralogical evidence indicates that the Williton Member is bounded by erosional disconformities and, at present, can only be positively recognised in North Somerset.

The litho-and biostratigraphy of Boxford quarry and Winterbourne pit are described in detail. Boxford quarry displays a section through parallel bedded soft white chalks and hardgrounds which dip at 25° SSE, overlain by a chalk mélange composed of displaced and deformed blocks of hardground surrounded by calcarenitic chalk. The succession is of late Coniacian to mid Santonian age and is interpreted as being the result of intra-Upper Cretaceous tectonic activity. Winterbourne pit exposes a late Santonian to early Campanian sequence of poorly phosphatic chalks and hardgrounds containing an abundant macrofauna. This deposit is the same age as, and in part similar to, the classic phosphatic chalks of northern France, to which it is compared. However, it is best explained as resulting from a continuation of the abnormal tectonic and bottom-current conditions indicated by the older, atypical chalks of the Boxford area.

Trend surface analysis has been used widely in geology and geomorphology but only rarely has it been applied to directional data. This neglect stems from the inapplicability of normal trend surface procedures to such data. An adaptation of normal trend surface procedures specifically designed for use with directional data is, however, available as a FORTRAN IV computer program. This technique is described and its usefulness in generalizing regional patterns of flow is illustrated by applying it to data representing ice flow direction in Central Scotland.

Abundant specimens from the middle or upper Tremadoc beds in the Napton Fields Borehole, Warwickshire, are referred to one variable species, Kiaerograptus? quasimodo sp.nov. Two-stiped forms typical of Kiaerograptus co-exist with ‘one-stiped’ forms in which the first stipe consists only of Th 11. Rare specimens with three primary thecae gave rise to forms with one, two? or three stipes.

Metabasic assemblages belong to the prehnite-pumpellyite and greenschist facies. The isograds pumpellyite-in, pumpellyite-out/clinozoisite-in and biotite-in have been mapped, and divide the area into four metamorphic zones. Field and petrographic evidence indicate that the metamorphic crystallization was largely syn-and immediately post-tectonic, viz. end-Silurian to Devonian. The use of published Schreinemakers' bundles indicates that most of the prehnite-pumpellyite-bearing assemblages formed at high grades within the facies and that the greenschist facies rocks crystallized in the higher pressure field. As the amount of calcite increases so diagnostic Ca–Al silicates are reduced and eventually eliminated from assemblages. Contrary to recent claims, the evidence indicates that the Gwna Group and the Gwyddel Felsitic Beds of Llŷn were metamorphosed prior to the Arenig.

The Ordovician trilobite fauna of the Great Paxton Borehole, Cambridgeshire, consists of twelve species including the seven new species; Segmentagnostus stubblefieldi, Trinucleus bicallis, Bergamia artemis, Protolloydolithus salax, Ogygiocaris macrops, Merlinia anxia and Bohemilla tridens. The fauna recalls that from the lower Llanvirn of the Shelve area, Shropshire, but the possibility of an upper Llanvirn age remains.

Ultrabasic and basic lavas are interbedded with metamorphosed Lower-Carboniferous sediments in the northern slope of the Alborz mountains, NE Iran. In the outcrop area at least 15 individual units of ultrabasic lava have been observed. Flow units range in thickness from a few metres up to about 70 m. The inner parts of the flow units are holo-crystalline, showing a poikilitic texture with rounded small crystals of serpentinized olivine surrounded by large crystals of clinopyroxene (‘wehrlitic facies’). The upper portions of the thicker units are olivine-free, and pyroxene, sometimes accompanied by brown hornblende, is set in a groundmass of fine-grained epidotized plagioclase (‘doleritic facies’). In the upper and lower margins of flows the groundmass is devitrified to chlorite and tremolite. Small-scale differentiation and igneous lamination is observable in transition zones between the wehrlitic and doleritic ‘facies’. The upper doleritic facies and other individual basic units have a tholeitic chemistry. In contrast, the chemical composition of wehrlitic rocks (which predominate amongst the exposed rocks in the area) is comparable with Archaean ultrabasic lava flows in Canada and southern Africa.

Two Devonian biogeographic provinces are recognised in China, based on brachiopod distribution. The Junggar-Xinan Province to the north shows a mixture of European and North American elements, but notably no stringocephalids are present. The South China Province, which is subdivided into three subprovinces possesses more elements of European type.

The Keystone/Muddy Mountain thrust of South East Nevada provides a spectacular example of a thrust sheet that has travelled across the earth's surface for a distance of at least 25 km, probably as much as 50 km. Along the thrust a Palaeozoic to early Mesozoic succession (> 4 km thick) has moved over a channelled erosion surface cut into Jurassic aeolian sandstone. Clasts in the channels are stratified, with those in upper layers being easily matched with the rocks in the thrust sheet – thus the clasts ‘herald’ the approach of the sheet. The clasts are only weakly deformed by the thrusting which belongs to the Sevier-Laramide orogeny.

Erosion appears to be a significant if not crucial factor in the emplacement of the Keystone thrust sheet. Adopting an erosion rate of 1 mm/a (in accord with Alpine and Himalayan estimates) and a rate of thrusting of 5 mm/a (in accord with estimates from the Canadian Rockies) it follows that the thrust sheet was ‘half-eroded’ after travelling about 25 km.

It is concluded that large displacement (i.e. > 25 km) may be impossible without erosion and one of two ‘erosion models’ would greatly facilitate transport up to 50 km, which is the likely maximum displacement.

The discovery of marine fossils in the Upper Palaeozoic of the Oslo Region suggests a previously unknown marine transgression of probable middle Carboniferous age. The fossiliferous sequence in the Oslo district was probably deposited in a very shallow marine environment as indicated by its fauna, ooids and the strong micritization of the fossils. The discovery of this sequence is consistent with the rift model for the Oslo Rift Zone, and suggests a connection with the Variscan Ocean.

About 300 gravity stations were established at 2–4 km intervals along an E-W profile across the Lower Benue Trough from Gboko-Nsukka-Auchi with the main objectives of investigating the nature and configuration of the basement complex underlying the trough and estimating the thickness of the sedimentary cover rocks. The resulting Bouguer anomaly profile shows a series of alternating positives and negatives. For a preliminary interpretation, the positive anomalies are attributed to shallow basement and the negative anomalies to sediment-fill of maximum thickness, 4250 m.

New observations of sedimentary and tectonic structures confirm ‘pre-cleavage’ folding of the Arenig Loweswater Flags and Kirk Stile Slates. A major recumbent fold is thought to have developed by gravity gliding during Arenig-Llanvirnian times.

The brachiopod fauna of the Gorran Quartzites of south Cornwall is described; it comprises five orthid genera. Three taxa are described under open nomenclature, and one new species is assigned to a new genus (Schalidomorthis stubblefieldi). The fauna supports the Llandeilo age suggested by accompanying trilobites. There is no brachiopod evidence to indicate that the quartzite pebbles of the Triassic Budleigh Salterton Pebble Bed are derived directly from the Ordovician of Cornwall.

One nearly complete specimen of the new Oscillatoriaceae-like filamentous microfossil Doushantuonema peatii gen. et sp. nov. is described from the Sinian (late Precambrian) of western Hubei Province, China. This constitutes the first reliable record of the Oscillatoriaceae-like filaments in the Precambrian rocks of China.

Abundances of rare-earth elements (REE) and Th, Ta, Hf, Sc, Co, Ba determined by instrumental neutron activation analysis show similarity between lamprophyres and other potassic rocks including kimberlite. The Indian lamprophyres have fractionated REE patterns with enrichment of light REE. The light REEs show more variation than the heavy REEs within the group.

Lamprophyres occurring in intimate association with the alkaline basalt may be genetically related. The trace element characteristics of the abundant lamprophyre dykes in granitic terrain are unlikely to be generated by assimilation of alkaline basalt by granitic crust. Small amounts of partial melting in mantle pockets enriched in incompatible elements as a result of metasomatic processes would explain the elemental concentration observed in the lamprophyres.

Recently discovered specimens from the Portrane Limestone Formation of eastern Ireland are regarded as topotypes of Tretaspis radialis Lament and used to further characterize the species. The features shown by these specimens confirm the close relationship between T. radialis and forms from Zones 2–4 of the Cautleyan Stage of northern England and Wales and allow its differentiation from T. moeldenensis Cave and from another related form of low Rawtheyan age which is here erected as a new species, T. caritus sp.nov.

Devonian Antiarchi in China are chiefly distributed in the S and W of the country. They are represented by 17 genera and more than 26 species, of which three genera are cosmopolitan, namely Asterolepis, Bothriolepis and Remigolepis. The early Devonian Antiarchi fauna, Yunnanolepis, Phymolepis, Zhanjilepis, is an East Asiatic fauna. The middle and late Devonian faunas are essentially endemic and associated with few cosmopolitan elements, their geological ages, however, are different from those of the cosmopolitan antiarch taxa elsewhere. As considered in the present study, six main antiarch assemblages occur: (1) Yunnanolepis-Qujinolepis assemblage (Lower Devonian), (2) Xichonolepis-Wudinolepis assemblage (Eifelian), (3) Hunanolepis tieni-Bothriolepis sinensis assemblage (Givetian), (4) Bothriolepis kwangtungensis-Bothriolepis lochangensis assemblage (Givetian), (5) Remigolepis spp. assemblages (Frasnian-Famennian), (6) Sinolepis-Asterolepis sinensis assemblage (Famennian).

X-ray diffraction analysis of metamorphic rocks from the Start peninsula shows that the dominant mineral assemblage in the Start schists is quartz-muscovite-chlorite ± paragonite ± albite. The assemblage in the Devonian phyllites to the north of the Start boundary is quartz-muscovite-chlorite and the crystallinity of the white mica there is indicative of greenschist fades. The b0 parameter of white micas indicates that the metamorphism was of an intermediate facies series (Barrovian type), but of a lower pressure variety to the north of the Start boundary juxtaposed against a higher pressure variety to the south. No evidence exists of the high pressure metamorphism needed to support tectonic models in which the Start boundary is identified as a suture representing a Variscan subduction margin.

The trilobite family Lichidae is represented in the Middle Ordovician of Virginia by silicified remains of species of Hemiarges and Amphilichas. One new subspecies, Hemiarges turneri Chatterton & Ludvigsen rasettii, is described. Development stages of both genera are illustrated. The bulla of H. turneri rasettii appears in the meraspis, whereas it is present in the protaspis of a Devonian species. The late metaprotaspis of Amphilichas has a small fixigenal spine, a feature shared with protaspides of the family Odontopleuridae.