A lower Tertiary lateritic paleosol resting on a plateau basalt was penetrated by drilling at DSDP Site 336 on the NE flank of the Iceland—Faeroe Ridge. The sea floor at the site is about 800 m below sea level and about 400 m below the generally smooth, flat and largely sediment-free top of the ridge. The paleosol is approximately 30 m thick and can be divided into four subunits, in ascending order, basaltic rubble, red clay with altered basaltic clasts, interlayered red and pale-orange clay, and red clay. The paleosol is overlain by about 300 m of marine mudstone of medial Eocene to medial late Oligocene age that was deposited in progressively deeper water through time. About 170 m of Pliocene and Pleistocene glacio-marine sediments unconformably overlie the Paleogene deposits.

In the lowest subunit of the paleosol, feldspar, pyroxene, magnetite and chlorite decrease in abundance abruptly upward and are replaced by montmorillonite and small amounts of hematite and goethite. At the contact between the second and third subunits of the paleosol, kaolinite becomes an important constituent and increases greatly in abundance upward. In the uppermost red clay subunit, kaolinite has completely replaced montmorillonite and the amount of hematite and goethite increases markedly. Within the paleosol subunits, the relative amounts of silicon, ferrous iron, magnesium, calcium, sodium, and potassium decrease upward, whereas the amounts of aluminum, ferric iron, and titanium increase upward. The red and pale-orange clay subunit contains layers characterized by veinlet-like structures alternating with more massive layers. The veinlet network is thought to have developed by segregation of ferric iron and alumina as a result of chemical weathering of basalt and possibly thin overlying airfall tuffs.

The paleosol indicates a humid, warm climate and demonstrates that the Iceland-Faeroe Ridge was above sea level during the early Tertiary. The ridge formed the main part of the Thulean land bridge that permitted free migration of land mammals between North America-Greenland and Europe prior to late Eocene time. It developed during the early Tertiary break-up and rifting apart of North America-Greenland and Europe. Formerly situated over an active mantle plume or hot spot, the ridge subsequently subsided in late Eocene and Oligocene time, eventually permittingfree interchange of marine waters between the Norwegian-Greenland Sea and the North Atlantic Ocean. Basalts of the Iceland-Faeroe Ridge are simijar in age and character to other basalts of the North Atlantic early Tertiary igneous province on the Rockall and Voring Plateaus, northern Ireland, Scotland, the Faeroe Islands, East and West Greenland, and Baffin Island. Bauxite, lignite, and laterite associated with some of these basalt sequences, as well as vertebrate, plant, and microfossil remains, suggest a relatively uniform, warm, humid climate in the early Tertiary throughout the North Atlantic area and into the region of the Arctic Ocean.

At the International Geological Congress held in Sydney, Australia, in August 1976 a Symposium of papers and discussion on ‘The Precambrian–Cambrian Boundary Problem’ was organized by the author in his capacity as Project-Leader/Chairman of the international Project 29 Working Group on the Precambrian–Cambrian Boundary. The following seven papers arose from this symposium. Project 29 is part of the current research under the auspices of the International Geological Correlation Programme (I.G.C.P.). which is sponsored jointly by the United Nations Educational. Scientific and Cultural Organization (U.N.E.S.C.O.) and the International Union of Geological Sciences (I.U.G.S.).

The present position of Sri Lanka and its past fit in Gondwanaland are investigated in relation to the development of the Indian Ocean. The 3 stages in the evolution of the Indian Ocean are shown to be controlled by fundamental NW, NS, and NE Precambrian lineament directions in Sri Lanka and South India. These older lineaments were rejuvenated in the Mesozoic–Tertiary to form oceanic transform faults which determined the phases of Indian Ocean floor spreading.

The drift succession in east-central Ireland is the result of a series of ice movements spreading from major centres of dispersion within theIrish Sea Basin and over the north-central Irish plain, and from local mountain sources. These glaciations have produced laterally and vertically complex sequences of deposits. The large-scale events influenced almost the entire area; problems of correlation emerge when considering episodes of relatively restricted extent such as those associated with upland ice-caps in the S and the hitherto unreported readvances which interrupted the withdrawalof ice-sheets across the northern part of the region under examination. Thetask of assigning the older units to particular Quaternary cold stages is frustrated by the absence of interstratified organic horizons. Two possible models of glaciation are considered: one may be regarded as ‘traditional’; the other requires a much shorter period of time by assuming that the stratigraphy records differences in the relative strengths of essentially contemporaneous ice-masses.

Twenty-three species of the Family Discoasteraceae Vekshina, 1959 recovered from 18 samples of the Blue Clay at Fort Chambray, Gozo, and 31 samples from Fomm-Ir-Rih Bay, Malta, have been studied under light and scanning electron microscopes. Fourteen Middle Miocene species are reviewed, their stratigraphical ranges and importance as marker species discussed. Nine species are described as new. On the basis of the discoaster species present, a Middle Miocene age (NN.6 Discoaster exilis Zone – NN.7 Discoaster kugleri Zone) for the Blue Clay in Malta and Gozo is suggested.

Post-Karroo melilite basalts intrude Cretaceous and older sedimentary units in the Cape Province, South Africa. K-Ar ages determined from 4 occurrences range from 63–75 Ma b.p. (Late Cretaceous to earliest Tertiary) and are significantly older than alkaline intrusions to the 5, on the Alphard Bank. These igneous intrusions may be part of a linear trend that connects young oceanic volcanism at Bouvet Island with Cretaceous kimberlitic activity in southern Africa. This lineament nearly parallels the Walvis Ridge and a hot spot model for its origin is examined.

A liquefaction layer displaying ball and pillow structures occurs within the back reef facies of the Cawdor Limestone (P2 zone) near Wirksworth. This layer consists of pillow-shaped masses of coarse biosparite within a biomicrite matrix. The pillows are 0.6–0.8 m thick and 1.5–4.0 m across. Experiments using layers of calcareous sand above calcareous mud have demonstrated that such structures may be produced by subjecting saturated sediments to seismic shocks. These Viséan carbonate ball and pillow structures are attributed to loading, resulting from liquefaction of underlying calcareous mud during the passage of earthquake shock waves associated with the Gulf Fault.

The Hartshill Formation (c. 270 m) consists largely of shallow-water feldspathic sandstones and greywackes lying unconformably on Precambrian (Vendian?) volcanic rocks and below shales with the first olenellid trilobites. Five members are recognized. The Park Hill Member is conglomeratic and arkosic near the base, passing up into green-grey megarippled quartzites with some thick shale bands. The Tuttle Hill Member is more shaly and glauconitic with conspicuous bioturbation. The Jee's Member is of distinctly cross-laminated glauconitic, feldspathic greywackes and shales with numerous trace fossils. Conglomerates, shales, sandstones, phosphorites and limestones comprise the Home Farm Member, withadiverse Tommotiantype shelly fauna and stromatolites near the top. Massive arkoses and greywackes of the Woodlands Member yield similar shelly fossils in calcareous beds at the base and top while the overlying Purley Shale yields the first Lower Cambrian trilobites.

In the Anti-Atlas, trilobites occur below the zone of Fallotaspis tazemmourtensis of Hupé (1953) and even somewhat below the first archaeocyathids of the region. Most of them are opisthoparions (Hupetina gen.nov is described), and the olenellid Eofallotaspis gen.nov. probably is ancestral to Fallotaspis. The age is concluded not be younger than the lower Atdabanian of the Siberian platform. In the High Atlas, in the area called Ounein, a complete succession of trilobites from the low Lower Cambrian through the Middle Cambrian is being studied. The oldest trilobites encountered here are referred to the new genus Lemdadella. Correlation with the Anti-Atlas or other regions is uncertain.

The name Trawscoed Mudstone Formation is proposed for previously undescribed mudstones cropping-out between the Caradoc Nod Glas Formation (‘Gwern-y-Brain Group’ of Wade, 1911) and the overstepping Rhuddanian Powis Castle Conglomerate Formation some 5 km NW of Welshpool, North Wales. The mudstones have a fauna, dominated by brachiopods and trilobites, which indicates that they are contained within the Cautleyan Stage of the Ashgill Series and suggests deposition in a deep shelf environment.

Thirty samples of Upper Tertiary basalts intruding marine and continental sequences were by the K-Ar method. Four volcanic phases are recorded: (a) 24.8±1.5 Ma of the Raqabat e Na'ame dike in Central Sinai; (b) 20.4±0.7 Ma of basalt intrusions in Central Sinai and the Arava. Some of these are offset by E-W to NE-SW dextral faults of the Central Sinai – Negev Shear Zone; (c) 14.5±0.3 to 4.9±1.3 Ma of basalt flows in the Eastern Galilee and the Coastal Plain; (d) 2.7±0.6 Ma of ‘En Yahav dike. These results contribute to the correlation between Tertiary continental formations from different areas, and put limits on the age of tectonic events, such as folding in the Syrian arc, faulting in the Central Sinai - Negev Shear Zone and shearing along the Jordan Rift.

Masirah Island lies off the SE coast of Oman and comprises a fully developed, though tectonically disturbed ophiolite, unconformably overlain by early Tertiary limestone. The ophiolite consists of harzburgites, cumulate gabbros, a sheeted dyke complex, and pillow lavas with sediment intercalations. Within the ophiolite occur granites the geochemistry of which, particularly their high K2O and Rb, and low Zr and Zr/Nb, ismore typical of a continental crust environment and suggests that at the time of their formation continental crust existed beneath or immediately W ofthe Masirah Ophiolite.

Simple expressions given in terms of Mohr diagram parameters may be used both to check the accuracy of Mohr diagram constructions and/or to replace particular constructions in stress analyses of brittle rock failure. Examples of expressions relating to two common types of composite failure envelope are given together with brief examples of their possible application.

Stromatolites of the groups Linella, Tungussia and Tifounkeia in association with thrombolites occur in abundance throughout the whole Lie de Vin Series, the middle part of the Adoudounian Group which consists of Calcaire lnférieur, Lie de Vin Series and Calcaire Supérieur. A Late Precambrian age is suggested for these stromatolites.

As in Kashmir and Arunachal Pradesh (NEFA) Himalayas, the Upper Palaeozoic (Lower Gondwana) sequence in Sikkim Himalayas contains basic lavas. These are interbedded with boulder bed/pebble slate, sandstone andshale, exposed in a tectonic window. Geochemically the basic lavas are characterized by high contents of TiO2, K2O, P2O5 and ‘incompatible’ trace elements. The chemistryis compatible with a small degree of partial melting under high pressure ofa titan-phlogopite-bearing peridotite mantle. The only primary quench phases are frequent apatite, magnetite and profuse ilmenite, the latter accounting for the high FeO/Fe2O3 ratio of the rock, and demonstrating rapid crystallization. The geochemistry of the lavas appears to be consistent with basic volcanism associated with the initiation of continental rifting. From this study and from a consideration of the geochemistry of the volcanic rocks of similar age in Kashmir area, it is suggested that rifting of the northern continental margin of the Indian plate and formation of a transitional crust during Upper Palaeozoic times are important geotectonic features in the Himalayan region.

Schemes of Scottish Caledonian metamorphic zonation involving the Thermal Anticline have traditionally been used for reconstructing movement on the Great Glen Fault. Interpretation of the highland zonal pattern in terms of inverted zones severally parallel to the Moine Thrust and to the Highland Border Fault, representing perturbation of isotherms by under-thrusting, can be fitted to either sinistral or dextral models of transcurrent motion.

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.

Assemblages of calcareous foraminifera and algae have been examined in thin sections of Dinantian limestones from the Skipton, Broughton, Hetton, Eshton, Swinden and Lothersdale anticlines in the Craven Lowlands. Provisional identifications are listed for each assemblage and a correlation of the rock successions is suggested. The assemblages range from late Tournaisian to late Viséan in age, in terms of the Belgian divisions, and from Courceyan to Asbian in terms of the new chronostratigraphic stages of George et al. (1976).

Folds of a 12 mm thick calcite-rich vein, embedded in slate and with a primary planar fabric of parallel, thin and plate-like calcite crystals, or laminae, have a vein thickness/arc length ratio near 1. Folds were first entirely dependent for development on intra-laminar strain and inter-laminar sliding. As limb dips increased, however, pressure solution began to thin laminae in limb regions only. As adjacent inter-laminar surfaces met at fold inflexion points, where laminae were first cut through, loss on fabric-cutting surfaces began to replace inter-laminar pressure solution. The resulting stylolites grew across the vein in fold limbs, at the limit eliminating them. In contrast, in folded equigranular calcite rocks stylolites are widely developed in both limbs and hinges, and eventual fold collapse through late stage concentration of pressure solution takes place in fold hinges and not limbs.

The oldest archaeocyathid fauna from Tiout (Anti-Atlas, Morocco) contains 15 species belonging to 11 genera. The following species: Aldanocyathus cribratus, Neoloculicyathus magnus, Coscinocyathus primus, C. secundus, C. fasciola, Tumulifungia marocana, Gordonifungia cowieiare new. The biostratigraphy of this archaeocyathid fauna demonstrates that the lower boundary of the Amouslekian stage should be moved downwards to within the ‘Calcaires Supérieurs’ of the Adoudounian (Assadassian or equivalent Ouneinian). One or perhaps more archaeocyathid and trilobite zones may yet be found beneath this boundary at Tiout. The uppermost ‘Calcaires Superiéurs’ may be dated, on the basis of Archaeocyatha, as equivalent to the Atdabanian stage, but not to the lowest part of it. The underlying fossiliferous horizons should be equivalent to all or part of the lower Atdabanian. The Precambrian–Cambrian boundary in Morocco can be looked for lower in the succession and defined on the basis of other fossil groups.