Both geologists and archaeologists will be under a debt of BOTH gratitude to Messrs. King and Oakley for their recent paper on the Pleistocene sequence of the lower part of the Thames Valley (I). Not only have they conveniently summarized the results obtained by other field-workers, but they have contributed two postulates of great importance. These are: (a) the probability of a major period of erosion between the deposition of the Lower Loam and the Middle Gravel of the Boyn Hill Terrace succession; and (6) the recognition of a period of erosion between the formation of the Lower Flood Plain Gravel and the Post-Pleistocene alluvial beds.

The discovery and dating of a volcanic ash bed within the upper Phosphoria Formation in SE Idaho, USA, is reported. The ash occurs 11 m below the top of the phosphatic Meade Peak Member and yielded a 206Pb/238U date of 260.57 ± 0.07 / 0.14 / 0.31 Ma, i.e. latest Capitanian, Guadalupian. The stratigraphic position of this ash near the top of the Meade Peak phosphatic Member of Phosphoria Formation indicates plausible completeness of the sedimentation within the Guadalupian–Lopingian and probably at the Permo-Triassic (P-T) transitions. The new radiometric age reveals that the regional biostratigraphy and palaeontology of Phosphoria and Park City formations requires serious reconsideration, particularly in cool water conodonts, bryozoans and brachiopods. The new age proposes that the Guadalupian–Lopingian boundary (GLB) coincides with the Meade Peak – Rex contact and consequently with the end-Guadalupian extinction event. The lack of a major unconformity at the P-T transition suggests that the effects of the Sonoma orogeny were not as extensive as has been assumed.

The Lower Cretaceous Wealden sideritic ironstones have a wide occurrence and great potential to aid the reconstruction of the depositional environments of the Weald Basin in SE England. However, mineralogical and geochemical datasets on the ironstones are scarce in the literature. Geochemical and mineralogical data on the sideritic ironstones are presented from the Wadhurst Clay Formation within the Weald Basin. The mineralogy of the ironstones was examined using a PANalytical X'Pert Pro X-ray diffractometer and PANalytical's HighScore Plus software. Elemental composition of the ironstones was measured using a PANalytical MiniPal2 ED-XRF (benchtop X-ray spectrometer). The examination of the mineralogy of the Wealden ironstones confirms the presence of early diagenetic siderites. The trace-element assemblage shows that the sideritic ironstones are chemically pure pointing to a freshwater origin. The sideritic ironstones reveal anoxic conditions and palaeo-salinity in the basin. More generally, it is suggested that the composition of the host rocks has significant controls on the composition of sideritic ironstones in sedimentary basins. This work reinforces the importance of the composition of sideritic ironstones as useful non-traditional data for understanding the depositional settings of sedimentary basins, especially when traditional datasets are not readily available or insufficient.

The Lower Cambrian in northwest Scotland is one example of a Lower Palaeozoic ‘orthoquartzite-carbonate’ succession deposited on a slowly subsiding, peneplained Precambrian basement during a period of relative sea-level rise. This particular setting led to the development of a very wide, low gradient shelf which was extremely sensitive to minor sea-level changes. The basal quartz arenite section (Lower Member-Pipe Rock) is a transgressive, tide-dominated systems tract, but lacks a systematic parasequence architecture because of three factors: a fluvial sediment flux was insufficient to induce shoreline progradation, accommodation space was limited during sea-level falls (which are commonly expressed by widespread erosional surfaces), and sediment yield to the shelf by transgressive reworking was a major contributor towards the preserved stratigraphy. The storm-dominated Fucoid Beds represent a condensed section and also show the effects of rapid and widespread facies belt oscillations because of the low shelf gradient. An overlying highstand systems tract is also lacking, partly due to the absence of a large fluvial sediment yield and also due to lowstand and transgressive reworking. An erosively based tidal sandsheet at the top of the Fucoid Beds, interpreted to be a lowstand systems tract, therefore rests directly on the condensed section of the underlying sequence. This was in turn reworked into linear tidal sandbanks (Salterella Grit) during slow sea-level rise, prior to the next major transgression. The limited accommodation space therefore introduced a preservational bias towards deepening-upward trends on a parasequence and sequence scale. The oscillations in facies belts, episodic subareal exposure and the potential to remove substantial portions of systems tracts suggests that Lower Palaeozoic ‘orthoquartzite’ successions may exhibit regular and abrupt vertical shifts in depositional environment which, given their subtle lithological character, may require detailed analysis to identify. Such successions may also display incomplete development of several components of transgressive-regressive sequence architecture.

The granitic rocks of the Tarim large igneous province (LIP) are temporally and spatially related to mafic intrusions. However, their tectonic setting and genetic relationship are debated. Here, we report geochemical, and zircon U–Pb–Hf isotopic results for three alkali feldspar granitic plutons in the Halajun area, western margin of the Tarim Block. Zircon U–Pb ages suggest these plutons were emplaced at 268–275 Ma, coeval with the neighbouring mafic–ultramafic complexes and syenitic rocks. These granitic rocks have high contents of SiO2, alkalis, Rb, Th, Zr and REE (except Eu), and high ratios of FeO*/MgO and Ga/Al, and show strong depletions in Ba, Sr, Eu, which are commonly observed in the A1-type granites. Zircon Hf isotopes reveal a limited range of εHf(t) values from −1.0 to +3.5 for different samples from three granitic plutons, obviously higher than those (mostly <0) of the mafic rocks. This distinct difference, along with a Daly gap and small volume of mafic rocks, argues against extreme fractionation of mafic magma as the main origin of the A1-type granites. Instead the A1-type granites were most likely derived from partial melting of newly underplated rocks triggered by the upwelling asthenosphere, followed by extensive fractionation. These A1-type granites were emplaced within an anorogenic setting during the late stage of the Tarim LIP, which possibly lasts for more than 30 Ma. The Piqiang mafic–ultramafic complex directly stemmed from asthenospheric mantle and Halajun A1-type granites represent two manners of vertical crustal growth.

The Quaternary Bandas del Sur Formation in the south of Tenerife comprises a complex sequence of pyroclastic rocks and lavas. In contrast to the NW- and NE-Rift zone on Tenerife, the S-Rift zone comprises a number of characteristics with respect to the morphological features, eruption cyclicity and the geochemistry of the volcanic deposits. Various flank eruptions of the Las Cañadas volcano associated with basaltic lavas and the formation of cinder cones within the Bandas del Sur are important volcanic units for understanding the explosive volcanic cycles during the Pleistocene on Tenerife. A number of palaeomagnetic studies, as well as major and trace element geochemistry and two radio-isotope dates (K–Ar), have been carried out on prominent cinder cones, in order to discover their stratigraphic position. Combining our results with previous K–Ar data, the cones and lavas can be subdivided into three stratigraphic units. The first unit contains cinder cones with reverse magnetization and Y/Nb ratios between 0.37 and 0.41. Cinder cones which belong to the second unit show normal magnetization and Y/Nb ratios of < 0.35. The third unit comprises cinder cones with normal magnetization and Y/Nb ratios of about 0.47. The first two units were constructed between c. 0.948–0.779 Ma and 0.323–0.300 Ma. These units define volcanic cycles ending in violent Plinian eruptions. The third and youngest unit possibly marks the beginning of a further volcanic cycle that started c. 0.095 Ma ago.

The following description of new genera and species of Lower Ordovician Cryptolithids is the result of a stratigraphical and palaeontological investigation of the rocks in the Llangadock-Llandeilo district, Carmarthenshire.

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.

A dinosaur braincase from the Middle Jurassic (Bathonian) of Oxfordshire (England) is described. The specimen, which has historical significance, has been erratically attributed to either a sauropod or a theropod on the basis of vague phenetic resemblances. It is here re-interpreted in the light of recent cladistic analyses of dinosaurs, allowing the first proper character-based discussion of its affinities. It resembles those of ornithischian and prosauropod dinosaurs in the absence of a prominent, caudolaterally directed bony sheet from either the crista tuberalis (as in all theropods) or the crista prootica (as in all sauropods except juveniles of the eusauropod Shunosaurus). This braincase shows two synapomorphic characters of the Eusauropoda: the region of the cranium is rostrocaudally shortened and the long axis of the supratemporal fenestra is transversely oriented. For these characters, ornithischians, theropods, and prosauropods retain the plesiomorphic condition. It is concluded that the specimen is an important exemplar of a Middle Jurassic sauropod braincase and it is suggested that it could be from the eusauropod Cetiosaurus.

Thin-section observations and electron probe analyses, and trace element data are reported from a new mantle xenolith hosted in Miocene alkali basalt from the western flank of Simien shield volcano, Ethiopia. The spinel lherzolite enclaves contain variable proportions of olivine, orthopyroxene, green clinopyroxene and brown spinel, and have undergone deformation and partial recrystallization. They represent unmetasomatized, fertile xenoliths which were subjected to a late-stage melt–rock reaction. Trace element contents of clinopyroxene crystals are extremely low and quite different from those of the other xenoliths within the East African Rift System.

Batfishes of the family Ogcocephalidae are derived lophiiform fishes characterized by having a dorsoventrally depressed body and a distinctive series of morphological features. A new genus and species of batfish, Tarkus squirei gen. et sp. nov., is described from the Eocene (Ypresian) limestone of the celebrated locality of Monte Bolca, Italy. It is based on five well-preserved specimens that display a unique combination of characters (body moderately depressed; disk rounded in outline; caudal peduncle thick and stout; frontals with median groove for the illicium; teeth present on jaws and palate; illicial bone pitted and trilobate; body covered with thick slightly overlapping tubercles) that support its recognition as a new genus of the family Ogcocephalidae. Tarkus gen. nov. is also characterized by having distally branched pectoral-fin rays, a condition unique within the family, and by a peculiar structure of the axial skeleton, which possibly represents the plesiomorphic state for the ogcocephalids. Tarkus gen. nov. shows a certain degree of phenetic affinity with the extant shallow-water batfish genera Halieutaea and (more particularly) Halieutichthys. The specimens of this taxon are the first articulated skeletal remains of the Ogcocephalidae ever recorded as fossils, also representing the oldest members of the family known to date. The general structure of the skeleton of Tarkus gen. nov. provides unambiguous evidence that the existence of the modern ogcocephalid body plan was already established in the early Eocene, and probably originated well before that period. Palaeoenvironmental considerations suggest that Tarkus gen. nov. was a tropical batfish that inhabited the inner-shelf palaeobiotopes of the central-western Tethys.

The inversion temperatures of the quartz from twenty-five specimens of the Beinn an Dubhaich granite have been measured and found to correspond to the inversion temperatures of quartz from rhyolites previously studied. Optical and X-ray studies of the alkali and plagioclase feldspars indicate high temperature modifications. The Beinn an Dubhaich granite has the textural and compositional features of a granite together with mineralogical features normally associated with rhyolitic rocks. The results serve to emphasize that methods are now available which make it possible in some cases to determine whether a particular granite was formed by metamorphism of sediments or by crystallization of a magma. It is concluded that the older granites and those which crystallized at greater depths probably have undergone considerable rearrangement of their mineralogical and textural features subsequent to primary crystallization.

Aglaspidids represent an obscure group of lower Palaeozoic arthropods with a patchy biogeographic distribution. Before the recent description of a representative from Tasmania, these arthropods were exclusively known from Laurentia during the late Cambrian. Here we describe a new species, Aglaspella sanduensis sp. nov., from the Furongian of China, confirming that aglaspidids sensu stricto were already widely distributed worldwide by the late Cambrian; this demonstrates that some aglaspidids had great dispersal capabilities. A new diagnosis of the genus Aglaspella is proposed and the species formerly known as Aglaspella eatoni is assigned to a new taxon, Hesselbonia gen. nov.

THE finding of a small pebble of fine-grained quartz-dolerite in an exposure of the Upper Brockram in George Gill, near Appleby, by Professor Arthur Holmes in 1925 and its identification with the rock of the Whin Sill led to the direct establishment of the timeof injection of the Whin Sill and related dykes as post-Carboniferous and pre-Upper Brockram (1928, pp. 532–4). Since 1925 parties of students from the Durham Colleges’ Department of Geology have made each year a careful search for similar pebbles not only in the George Gill exposures but in a number of others in the Brackenber Moor neighbourhood. These efforts have not been rewarded with any success until the present year, when a party under my guidance made a thorough examination of the George Gill Brockram and Mr. A. R. Leathley, of Hatfield College, had the good fortune to hammer out a pebble of doleritic aspect.

The Tertiary fold-and-thrust belt on Brøggerhalvøya is characterized by a NE-vergent pile of nine thrust sheets. The sole thrust of the pile is located in Precambrian phyllites and climbs up-section to the northeast. Four lower thrust sheets consisting predominantly of Upper Palaeozoic sediments are overlain by two thrust sheets in the central part of the stack which contain a kilometre-scale syncline and anticline. The fold is cut by juxtaposed thrusts giving rise to the formation of three structurally higher basement-dominated thrust sheets. A multiple-stage kinematic model is proposed including (1) in-sequence foreland-propagating formation of the lower thrust sheets in response to N–S subhorizontal bedding-parallel movements, (2) a change in tectonic transport to ENE and out-of-sequence thrusting and formation of the kilometre-scale fold-structure followed by (3) truncation of the kilometre-scale fold and stacking of the highest basement-dominated thrust sheets by hind-ward-propagating out-of-sequence thrusting. The strain of the thrust sheets is predominantly compressive with the exception of the structurally highest thrust sheets, reflecting a temporal change to a more transpressive regime. Thrusting was followed by (4) N–S extension and (5) W–E extension. Comparison of the structural geometry and kinematic evolution of Brøggerhalvøya with the data reported for the fold belt further south allows us to assume a coeval evolution with the fold belt. A latest Paleocene/Early Eocene age for the main phase of thrusting is suggested for the West Spitsbergen Fold-and-Thrust Belt; the main phases therefore pre-date the separation of Svalbard and Greenland due to right-lateral movements along the Hornsund Fault Zone. The fold belt's temporal evolution followed by the formation of the Forlandsundet Graben can be linked with the plate-kinematic framework in the span between latest Paleocene and Middle Eocene times.

Relic pillows in the middle Proterozoic amphibolites, occurring in the Sirohi Road–Abu Road tract of Rajasthan, India exhibit contrasted mineral assemblages from core to rim – mimetic after the crystalline core, the zone of incipient crystallization, and the rim of the original pillows. The major element distribution pattern across the pillows indicates exchange of Na–Al for Ca (Mg, Fe) in an inner reaction zone, surrounding the core and in the inner margin of the rim, and Fe–Al exchange for Ca–Si at the outer margin of the rim.

Despite such exchanges around the rims, these pillows have retained their initial geochemical characteristics internally and thus have largely acted as closed systems during post-emplacement metamorphism. Mineral parageneses indicate that the contrasted mineral assemblages could evolve from domainal characters of the co-existing fluids, the compositions of which were only buffered by the reacting minerals during regional metamorphism.

The major, minor and trace element contents of the pillows and of amphibolites of diverse petrographic character in the region further establish that the pillow interiors and the massive amphibolites were least modified during metamorphism(s), and represent oceanic tholeiites. Their average 2300 ppm K, 4.5 ppm Rb, 150 ppm Sr, along with the K/Rb and K/Sr ratios of 510 and 15 respectively resemble that of the low K-tholeiites, occurring nearest to the trenches in modern island arcs. On the other hand, the higher values of 17300 ppm K, 4.9 ppm Rb, and 210 ppm Sr of the banded and the schistose amphibolites indicate that they were contaminated in various magnitudes by oceanic sediments.

Remains of coleoptera collected by Miss Chandler from the Barnwell Station beds (Cambridge) are described. Twenty-one recognizable taxa are recorded, all of which represent living genera or species. Five species are no longer found living in Britain and are confined today to arctic or sub-arctic environments. This interpretation of the fauna is in marked contrast to the identifications of P. Lesne, whose manuscript determinations are attached to the slides. He had attributed many of the specimens to new genera and species.

The fauna as here interpreted indicates a truly tundra environment and qualitatively and quantitatively resembles very closely other British coleopteran assemblages from the latter part of the Upton Warren (Mid-Weichselian) interstadial, i.e. about 30,000 years B.P.

The chief features exhibited by the heavy mineral residues from the various formations will now be summarized, but it is difficult to show, by tabulating or otherwise, the differences or resemblances between residues, although such may be quite obvious to the investigator. This is because the differences consist of a sum total of variations in size, shape, colour, and frequency of the mineralscontained in the residues under examination, and it is scarcely possible to indicate such differences in writing, without frequent repetition of words, there by involving a loss in clarity of expression, or if tables be employed, without losing sight of other connected data.

Smithian–lower Anisian strata in Peary Land, North Greenland, were deposited at ∼45° N on the northern margin of Pangaea in offshore to upper shoreface settings. The well-constrained succession (palynology and ammonite biostratigraphy) documents a remarkable shift from lycophyte spore-dominated assemblages in the upper Smithian to gymnosperm pollen-dominated ones in the lower Spathian in concert with a marked shift of +6 ‰ in δ13Corg. Correlation with other Smithian–Spathian boundary sections that record terrestrial floral changes indicates that the recovery of gymnosperms began earlier in the mid-latitudes of the Southern Hemisphere than in the Northern Hemisphere. The lycophyte-dominated Late Smithian Thermal Maximum is here interpreted as reflecting dry and hot climatic conditions with only brief seasonal precipitation unable to sustain large areas of gymnosperm trees, but able to revive dehydrated lycophytes. This suggests that the Late Smithian Thermal Maximum was a time of widespread aridity, which is also supported by red bed deposition in many areas globally, even as far south as Antarctica. The shift to gymnosperm-dominated vegetation during the cooling across the Smithian–Spathian boundary reflects a change to seasonally more humid climatic conditions favouring gymnosperm recovery, and could have been initiated by increased albedo over land due to the widespread aridity during the Late Smithian Thermal Maximum. The recovery of gymnosperm vegetation would have helped to draw down CO2 from the atmosphere and exacerbate global cooling.

THE plateau-lavas of Antrim cover an area of approximately 1,550 square miles—the largest area of Tertiary lavas in the British Isles. Although from the earliest daysof geological science these lavas have attracted many observers, very little has been done in the way of petrological study and, curiously enough, the dominant olivine-basalt lava has never been analysed.