A diverse fauna of trilobites, graptolites, inarticulate brachiopods, sponges, and a worm is described from the Tremadoc rocks cropping out in the Llangynog district, SW of Carmarthen. It permits identification of the Clonograptus tenellus Zone and older Tremadoc strata; younger Tremadoc strata are apparently absent. The fauna shows closest affinities with the Shineton Shales of Shropshire, while some of the trilobites also indicate a close relationship with those from the Tremadoc of NW Argentina.

A virtually complete Jurassic sequence recently drilled in north Lincolnshire is considered in a regional context. Liassic thicknesses and facies are largely unexceptional. The Frodingham and Pecten Ironstones are relatively thin and sandy, but the Marlstone Rock Bed is thicker and more ferruginous than elsewhere in the region. The Inferior Oolite is exceptionally thick and exhibits strong deltaic influence; equivalents of the Gristhorpe Member and Scarborough Formation of Yorkshire may be present. The Great Oolite was deposited in coastal-lacustrine-deltaic environments, more proximal than to the south or east. Thin Kellaways Clay separates the argillaceous Cornbrash from the Kellaways Sand. The organic-rich Lower Oxford Clay is thin owing to a basal non-sequence whilst the Upper Oxford Clay is condensed and less organic than in the East Midlands. The regressive West Walton Beds are followed by very thick Ampthill and Kimmeridge Clay sections beneath the Spilsby Sandstone. Regional thickness and facies analysis records the behaviour of the Market Weighton Block and reveals the influence of the Pennine High as both a positive tectonic feature and an occasionally active sediment source.

A small brachiopod fauna of early Permian age is recorded from pebbly mudstones and sandstones of the Phuket (Kaeng Krachan) Group at the Thai islands of Ko Muk, and Ko Phi Phi in the Andaman Sea. Most species belong to genera found in temperate to high Permian palaeolatitudes, whereas other Permian faunas from Thailand are strong in tropical affinities, suggesting that the pebbly mudstones are cool water deposits, contemporaneous with the late Asselian glacial deposits of Gondwana. New taxa are Arctitreta percostata sp.nov., Komukia solita gen.nov., sp.nov. (Rugosochonetidae), Cancrinelloides monticulus sp.nov., Rhynchopora culta sp.nov., Arionthia sapa sp.nov. and Elasmata retusus gen.nov., sp.nov. (Heterelasminidae).

The Songshan area is located in the southern part of the North China platform, which is one of the most completely cratonized tectonic units of China. Its basement has experienced a complex evolutionary history and was eventually consolidated at the end of early Proterozoic time about 1.7 Ga ago.

A systematic study has been made of the deformation history of the lower Proterozoic Songshan Group and the Archean Dengfeng Group. At least two widespread episodes of deformation can be recognised in the early Proterozoic Zhongyue tectonic cycle and three in the Archean Songyang cycle. Large scale and small scale interference patterns of the superimposed folding are investigated with the aim of recognizing possible regularities in their occurrence and of gaining an insight into the regional deformation history. Two important aspects of superimposition relationships are illustrated: the control of earlier structures upon later ones and the reform of the former by thelatter; their geometrical regularities are also dealt with respectively.

Humate-cemented sands (humicretes) are exposed at several locations along the foreshore and in gullies near Cape Flattery, North Queensland, Australia. Three broad types of humate accumulation are recognized: (a) pedogenetic; (b) groundwater; and (c) aquatic. Pedogenetic and groundwater humicretes usually have a grain-supported fabric in which quartz represents > 99% of the framework grains. Hand specimens of humicrete are brittle but disintegrate rapidly in 0.1 N-NaOH. Concentration of humate is considered to have occurred by vertically and laterally migrating groundwater, while induration has probably been caused by irreversible drying of the humic substances during periods of seasonal water-table lowering. Radiocarbon dating of an in situ root embedded in indurated humate near Cape Flattery has indicated a ‘background’ age of > 48000 C–14 years.

In northeastern Spitsbergen and western Nordaustlandet well preserved Late Precambrian diamictites have variously been interpreted as tillites or the product of tectonic activity. By focusing on the sedimentology of the diamictites in two key areas, this paper presents unequivocal evidence that the diamictites are indeed glacigenic, confirming the conclusions of previous field investigations. In particular dropstones in large numbers and striated stones are diagnostic of glacial transport, while other characteristics are strongly suggestive of glacial conditions.

Stratigraphic studies indicate two discrete glacial episodes, both belonging to the Varangian epoch. The earlier resulted in a thin tillite sequence deposited in a shallow shelf-tidal-lacustrine environment. It is closely associated with stromatolitic dolostones. The later episode resulted in a tillite sequence a few hundred metres thick with two units in northeastern Spitsbergen separated and bounded by dolostone units. Deposition occurred in a shallow marine environment but occasional uplift led to terrestrial conditions and the deposition of fluvioglacial sediments and the development of periglacial phenomena.

The weathering of a suite of basalt clasts, that have been transported by mass wasting downslope in the Cumulus Hills region of the Queen Maud Mountains, Antarctica, is examined from both geochemical and glacio-geomorphic viewpoints. Chemical weathering, predominantly oxidation and hydration, increases in severity from clast core to rim for the suite. These weathering processes and concomitant formation of a weathering rind are suggested to be an accumulative process, culminating in the disaggregation of the rock due in part both to the chemical breakdown of the interstitial and intersertal basaltic glass and to physical weathering processes.

Mass wasting rates in the range of 1.4 × 10−3−1.13 × 10−1 cm. y−1 are estimated, assuming that the style of transport is dry creep. These transport rates suggest that the rock-surface/air-temperature differences in the study area may have been as little as 0.5 °C and heating and cooling cycles as few as 1 cy. y−1 for the last 4.2 Ma.

Weakly deformed, low grade, Lower Palaeozoic metasediments from central Wales contain abundant stack-like intergrowths of chlorite and white mica that closely resemble stacks described from the Devonian Hunsruckschiefer of West Germany; the Ordovician Martinsburg Slate, New Jersey, U.S.A.; and elsewhere. Several theories have been proposed to explain the origin of such stacks, including a detrital origin; strain-controlled growth of chlorite on a detrital mica nucleus; and strain-controlled intergrowth during metamorphism. None of these satisfactorily explains the central Wales stacks. A detrital origin is precluded by the presence of many stacks with shapes too delicate to have survived transportation, and a lack of hydrodynamic equivalence between the stacks and the clastic host grains. Features inconsistent with strain-controlled growth are constant alignment parallel to bedding but non-systematic orientation with respect to tectonic cleavage, their common occurrence in undeformed rocks, and petrographic evidence that they precede the tectonic cleavage. It is proposed that the stacks formed during diagenesis and low-grade metamorphism, and before the onset of deformation, through mimetic growth on a primary bedding fabric composed of clay minerals.

Fission-track dating of zircons and apatites from tuffs and bentonites has produced the first isotopic ages for the type sections of the Ordovician and Silurian Systems. In the Ordovician the following ages have been determined: lower Arenig 493 Ma, lower Llanvirn 487 Ma, lower Llandeilo 477 Ma, upper Caradoc 463 Ma and upper Ashgill 434 Ma. In the Silurian, the following: lower Llandovery 437 Ma, lower Wenlock 422 Ma, upper Wenlock 414 Ma and Ludlow 407 Ma. The Ordovician-Silurian boundary is interpreted as occurring at about 436 Ma. Three North American Rocklandian bentonites yielded zircons whose ages average 453 Ma. This is about 10 Ma younger than supposedly correlative units in the British type sections.

A reinterpretation is attempted of the 25 years of graptolite ultrastructural work based upon the present state of knowledge. It is emphasized that studies need to embrace many more species of graptolites, particularly in the dichograptid groups, and with different growth stages, before the gross evolution of ultrastructural elements can be satisfactorily appraised. The factual (morphological, ultrastructural) data are themselves reappraised, summarized, and very tentatively related to Bulman's anagenetic grades of graptolite development.

Three heavy mineral associations have been recognized in Palaeogene sands from the Hampshire Basin: one typical of the Scottish Highlands to the north, one of the Armorican massif to the south, and one characteristic of the Cornubian massif to the west. These associations interplay throughout the sequence to produce 10 heavy mineral units correlatable over the basin. The bases of several of the units correspond to commonly accepted time-surfaces and encourage correlation between areas showing strong facies variation. Transgressive units are dominated by Scottish-type material, regressive units by Armorican or Cornubian detritus. There is a relationship between local source area uplift and regression, the main reason for which is that the widespread transgressions submerged or otherwise cut off more local sediment sources, allowing input from the Scottish Highlands, a positive feature throughout much of Tertiary time, to dominate.

Geochemical analyses of fresh bedrock samples indicate that the Afu biotite granites are characterized by enhanced values of a suite of trace elements, including Sn, Nb, W, Zn, Rb, Li, F th, Y and depleted in Ba Sr, and Mn. These geochemical data are also examined by R-mode factor analysis with the primary objective of isolating the significant factors accounting for the sample composition as derived from mineralization, alteration and lithology.

The Orthogonal varimax solution yields a five-factor model that accounts for 76% of the total data variance. Factors 1 (Nb, Rb, Li F) and 3 (Sn, W) can be attributed to the effect of mineralization and postmagmatic alteration; while Factor 2 (Mn, Sr, Ba Zr) is lithological, associated with barren rocks, unaffected by metasomatism. Factor 4 (Th, Y, Ga) and Factor 5 (Pb and Zn) are also associated with prominent mineralization. Thus the mineralized granites are characterized by high concentrations of Sn, Nb, W, Zn, Rb, Li F, Th, Y and Pb but ore formation is considered a product of postmagmatic processes.

From a study of silicified fossils, and in particular the microstructure of brachiopods, from the Wilmington Sands (Upper Cretaceous) of Devon, a model of skeletal silicification is proposed. Three distinct morphologies of silica were formed, controlled by the relative rates of silica supply and carbonate dissolution: (a) a fine-scale replacement of the original shell microstructure where silica was abundant; (b) a concentric ring morphology called ‘beekite’ where silica supply was limited, and (c) a granular white crust formed where carbonate dissolution was restricted. Silicification occurred during early diagenesis as a result of bacterial decay of organic matter intimately associated with skeletal fragments, within a sediment of restricted permeability. A build-up of CO2 probably caused dissolution of skeletal carbonate, and bicarbonate released from this caused local precipitation of silica. The proposed mechanism is belived to be of general applicability to micrite-rich carbonate sediments.

Quantitative data on the rhyolitic lavas of the Quaternary La Primavera volcano, Mexico, are presented. Lavas vary in form from domes and mesa lavas to short coulées. Average thickness is 100 m, average surface area is 2.7 km2 and aspect ratios vary from 1:7 to 1:25. Two petrological lava types are distinguished – porphyritic and aphyric. Porphyritic lavas occur on or within an inner ring fracture and are associated with an area of caldera lake deposits. Many features suggest that these porphyritic lavas were emplaced into the wet sediments or water of the caldera lake. Aphyric lavas are largely found to the south of this region and form large polygenetic structures extruded on dry land. The porphyritic lavas generally are smaller and have higher aspect ratios than the aphyric, which are attributed to their special environment of emplacement. Some porphyritic lavas extruded on dry land, outside the region occupied by the caldera lake, are, however, the thinnest on the volcano.

Large deposits of marine-sand occur in the Taw, Camel and Hayle estuaries of north Devon and Cornwall. Total carbonate concentrations reach 67% in the Hayle, 62% in the Camel, and 40% in the Taw. Well mixed, the sands contain modern skeletal debris of consistent composition, which persists up to 18 km and 12 km landward from the mouths of the Taw and Camel estuaries. Although primarily a molluscan sand, remains of barnacles, bryozoans, echinoids, foraminifera, sponge spicules, decapods and coralline algae are common. Carbonate mineralogy provided by these components (on a 100% carbonate basis) consists of 45% aragonite, 38% low Mg-calcite and 17% high Mg-calcite. Two estuaries of the southeast coast of Devon (the Exe and Teign) contain smaller carbonate concentrations of up to 9 and 14%. Values are low there owing to dilution by readily eroded cliff-talus from local exposures of New Red Sandstone. These Permo-Triassic sediments provide carbonate lithoclasts, however, which supplement the modern biogenic supply. Strontium values have been used to estimate the extent of carbonate lithoclasts supplied to the Exe and Teign. The present source of marine-sand of estuaries in southwest England is considered to be mostly near-shore detritus supplemented by eroded cliff-talus, derived largely from local outcrops. Once this material enters the estuarine regime it is available as a supply of sediment for further up-estuary transport.

Fabiania Silvestri, a morphologically distinctive larger foraminifer, is circum-global in distribution and is reported to be almost equally abundant in the three marine Tertiary provinces, Tethyan, Indo-Pacific and Caribbean-American. The genus is reported to range from Upper Palaeocene to the top of the Eocene. During the mid-late Eocene Fabiania seems to have been represented by three species, F. cassis (Oppenheim), F. cubensis (Cole & Bermudez) and F. saipanensis Cole. In the Indian subcontinent it is known only from eastern India, where it is represented by F. cassis and F. saipanensis. F. indica Nagappa is here regarded as a junior synonym of F. saipanensis Cole. F. cassis is reported for the first time from India. In eastern India, Fabiania is found to be restricted to the middle to upper part of the Middle Eocene.

Calymene quadrata King is re-described. Two new species of similar age and provenance are erected and considered to be closely allied to quadrata; all three forms are thought to be best placed in genus Gravicalymene Shirley. G. pontilis sp.nov., the stratigraphically oldest form suggests derivation of the group from an ancestor such as G. deani Ingham. G. arcuata sp.nov. is the youngest form. Variation in the preglabellar area between the three forms argues for an expansion of the diagnosis of genus Gravicalymene; this would allow it to contain forms previously placed in genus Sthenarocalymene Siveter.

It is suggested that the Benue Trough may have been initiated by the extension of the equatorial oceanic fracture zones onto the continent during the early stages of the separation of Africa and South America. A transcurrent movement along deep-seated faults of the basement is responsible for the structure of the trough. After a period of extension characterized by the sedimentary infilling of the trough and igneous activity, the trough is turned into a chain through a short phase of compression. A discrete pattern of ‘en echelon’ folds and the strain pattern deduced from the analysis of large scale and microfracturing correspond to a N–S to N160° E direction of compression coupled to a sinistral transcurrent movement along a NE–SW direction. The difference in age of the folding phase in the northern and southern parts of the chain indicates a diachronous nature for this tectonic event in relation to the wrench regime. The Tertiary evolution of the trough marked by a tensional regime resulting in an E–W extension is to be related to the Cameroon Volcanic Line.

A series of late Caledonian breccia dykes composed of Dalradian schist fragments are emplaced in the Leven Schists. The form and extent of the breccia dykes are described, and dilational and nondilational components identified as contributing to the space occupied by individual breccias. Fabrics and textures of the breccia material are related to transport mechanisms and later compaction. The breccias are considered to have evolved as fluidized systems.

Significant quantities of clinoptilolite-heulandite, lesser amounts of low tridymite-cristobalite, sparse euhedral biotite, apatite and fresh plagioclase accompany the abundant smectite in the mudrocks from the Corallian sequence in the Baulking and Uffington boreholes. The association is thought to be genetically related, of volcanic origin and formed from the in situ decomposition of volcanic ash. Smectite concentrations fluctuate, showing five maxima, but are unrelated to lithology and hence to environment. This suggests repeated ash-falls during the Corallian sedimentation in the Berkshire area. The initial volcanic episode appears to have been contemporaneous with the shoaling which initiated Corallian sedimentation in southern England, suggesting a common tectonic control.