Summary. Rhyolites overlying the basement granitic gneisses and granites adjacent to the selimentfilled Benue Trough were studied. Rb-Sr isochron age of 113 ± 3 Ma and initial 87Sr/86Sr rato of 0.7067 were obtained from two extrusive bodies which form Gboko and Ikyuen hills. It is shown that their eruption has some relation to crustal doming at the onset of the Benue rifting. The published age of the oldest exposed sedimentary infill of the trough is Albian. As a result of the investigation of these volcanic rocks from the basement margin, however, an earlier and absolute age for the initiation of the rift is implied and a late Barremian to early Aptian age is proposed for the formation of this continental rift.

Summary. As a direct result of new work in the Shelve Ordovician inlier, two new important extrusive andesitic members of a revised Stapeley Volcanic Formation, are described. These members were originally regarded as extrusive. However, they have for over half a century been considered intrusive and a brief literature review attempts to account for this anomaly. A palaeogeographic reconstruction suggests that the members represent the remains of two Llanvirn volcanic islands which, following subsidence, were overlapped and buried by later Llanvirn sedimentation. This reinterpretation considerably increases the volume of andesitic material known to have been erupted in Llanvirn times in this part of the Welsh borderland.

Summary. A rare and typically Lower Riphean stromatolite Plicatina is reported from the Indian subcontinent for the first time. Elsewhere, its only well-known report is from the Lower Riphean rocks of Morocco. The present form has been identified as Plicatina misrai, a new form-species. It occurs in the thick calcareous Kapkot Formation, which is a practically unfossiliferous and widespread rock unit of the Lesser Himalaya. The present report has wider implications in many aspects, especially in raising the level of confidence in assigning a definite age to the rock unit in which it occurs.

Summary. A fossil siphonophorid is described from the Palaeozoic rocks of the Enticho area in Tigrai, northern Ethiopia. This is the first fauna to be described from these rocks and the evidence supports an Ordovician age for the associated glacial rocks. Detailed lithostratigraphy of the area is also discussed.

Summary. A m´lange on Fredriksen Island, South Orkney Islands, is part of a Mesozoic subduction- accretion complex which formed along the western, Pacific side of Gondwana. It consists of a chaotic arrangement of irregular sized blocks, up to 8 m across, of basic pillow lava, chert, felsite and epiclastic sandstone in a pervasively sheared cataclastic matrix. Inclusions are typically lozenge-shaped and are characteristic of a tectonic m´lange. As the m´lange incorporates both possible ocean floor material that was accreted on to the continental margin and inner slope basin sediments it probably formed beneath the trench-slope basin along a shear zone at a high level in the subduction complex.

Summary. The large number of species assigned to Triarthrus Green are here allocated to three genera - ten species to a revised Triarthrus Green (late Caradoc-Ashgill), thirteen species to a revised Porterfieldia Cooper (Arenig-Llandeilo), and five species to Bienvillia Clark (Tremadoc-Arenig). Triarthrus lacks an anterior border furrow on the cranidium; this furrow is confined to the yoked cheeks. Both Porterfieldia and Bienvillia have an anterior border furrow on the cranidium; these genera are distinguished primarily on the length of the preglabellar field.

Summary. The Alas Formation (shelf limestones) of Sumatra is reinterpreted to be of late Visean age, on the basis of conodonts and brachiopods, rather than of Permian age as previously thought. It is, therefore, the oldest dated formation in Sumatra. The Alas Formation probably underlies or is equivalent to the lower part of the Kluet Formation within the Tapanuli Group.

Summary. Pleistocene deposits exposed at Alton Road Quarry, Farnham in 1980 have been sub-divided into two formal stratigraphical units of ‘member’ status. The ‘Wrecclesham Gravel’ is the lowest unit and consists primarily of fluvial sands and gravels. Silts which occurred as a channel fill within this member contained a macro- and micro-fossil flora indicative of open country conditions and included a species of moss previously unreported from the European Pleistocene. Tentative thermoluminescence dating indicates an Early Devensian age for this unit, although radiocarbon dating of the plant macrofossils yielded an age of a B.P. The overlying ‘Farnham Silty Loam’ is separated from the Wrecclesham Gravel by a discontinuous and variable thickness of matrix-supported gravels interpreted as a slope deposit. The Farnham Silty Loam appears to be, at least in part, of aeolian origin. Mineralogical investigations suggest that it is predominantly of local derivation, whilst thermoluminescence dating suggests that it is of Late Devensian age.

Summary. Quartz-keratophyres from an ensimatic island arc on Bømlo, southwest Norwegian Caledonides, resting on the Lykling ophiolite, have yielded a Rb/Sr whole rock age of 535 ± 46 Ma. This Cambrian age, which is a minimum age of formation for the ophiolite, indicates an early phase of subduction, corresponding with the orogenic activity known from northern Norway, i.e. the Finnmarkian. Before Middle Ordovician time, the ophiolite and ensimatic arc had been obducted onto continental crust and deformed, as they are unconformably overlain by a volcanic complex of subaerial rhyolites and andesites which have yielded Rb/Sr whole rock ages of 464 ± 16 and 468 ± 23 Ma respectively.

Summary. The late Triassic (Rhaetian) Cotham Member in southwest Britain was deposited in a shallow, dominantly freshwater lagoon and contains a bed of synsedimentary deformation which can be traced for at least 25 km. The bed includes microfaults and plastically deformed slump-folds. In south Wales and north Somerset the top of the bed is slightly eroded and desiccation cracks up to I m deep are present. The deformation was probably caused by earthquake activity and associated uplift in the north Somerset-south Wales area. Earthquake activity is inferred to have been part of the early Cimmerian tectonic phase in northern Europe. The bed of synsedimentary deformation is a stratigraphic 'event' which can be used for correlation in this area.

Summary. Pollen, plant macrofossils and Mollusca suggesting a mid-Ipswichian age are described from a clast of detritus mud found in gravels underlying the floodplain of the River Kennet at Thatcham, Berkshire. The clast of fluvial mud contained rich fossil assemblages giving evidence of deciduous forest habitats and fens, besides conditions within the river. Non-marine Mollusca from a sample of clay-silt from the interglacial site at Sandy Lane, Aveley are described. Thirteen species are added to the published list of Mollusca. Among these additions, Pseudamnicola confusa is important in providing the first evidence from the site of slightly brackish conditions. The fauna as a whole is similar to fluvial faunas of Ipswichian Interglacial age.