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.

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.

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.

Two examples of point bars in single-channel gravel-bed rivers in Wales illustrate some of the morphological and surface sedimentary features observed during a wider examination of 40 sites of recent (less than 100 years) channel sedimentation. The point bars consist of predominantly sandy gravel bar platforms overlain by discontinuous sand bodies. Cut bank exposures show generally massive sandy gravels abruptly underlying a silt/sand unit. Morphologically the bars are platformlike, with primary inner-attached, or secondary medial, chutes. This relief, together with the effects of seasonal vegetation, determines the locations of finer-grained (non-gravel) material. The frequency with which deposits produced by this type of channel sedimentation may be encountered in Quaternary and pre-Quaternary successions is briefly discussed.

A submarine fissure eruption of Upper Miocene age produced a modest volume of alkaline basalt at Low Layton, on the north coast of Jamaica. The eruption occurred in no more than a few hundred metres of water and produced a series of hyaloclastites, pillow breccias and pillow lavas, massive lavas, and dikes with an ENE en échelon structure. The volcano lies on the trend of one of the island's major E–W strike-slip fault zones: the Dunavale Fault Zone. The K–Ar age of the eruption of 9.5 ± 0.5 Ma. B.P. corresponds to an extension of the Mid-Cayman Rise spreading centre inferred from magnetic anomalies and bathymetry of the Cayman Trough to the north and west of Jamaica. The Low Layton eruption was part of the response of the strike-slip fault systems adjacent to this spreading centre during this brief episode of tectonic readjustment.

Planktonic foraminifera are recorded for the first time from the St Erth Beds but they are small and very rare. A late Pliocene G. inflaia Zone age is postulated on the presence of Globorotalia inflata and dextrally coiled Neogloboquadrina pachyderma. It is suggested that the depth of water at the time of deposition was much less than 100 m, possibly in the photic zone, and the palaeotemperature was in the range of 10–18 °C.

New conventional K–Ar dating of virtually unaltered pargasite phenocrysts extracted from a metabasalt of the uppermost Tremadocian Rhobell Volcanic Group, cropping out near Dolgellau, Gwynedd, north Wales, yields an age of 508 ± 11 Ma. This result provides a valuable new time-scale calibration point although incompatible with some other versions of the radiometric time-scale for the Lower Palaeozoic which have indicated ages of less than 508 ± 11 Ma for the Tremadoc/Arenig boundary.