Two distinct suites of dolerite, the Roraima Intrusive Suite (Pre-cambrian) and the Minor Dyke Suite (?Mesozoic) intrude the Guiana shield. The dolerites of the Roraima Intrusive Suite, which occur as major dykes, inclined sheets and sills, are tholeiitic in character and have been strongly differentiated. The series orthopyroxene-dolerite → pigeonite-dolerite → ferrodolerite → leucogranophyre represents the main trend. Hornblende-granophyres represent heteromorphs of late pigeonite-dolerites and early ferrodolerites. Differentiation was accomplished mainly by crystal settling probably in the presence of convection currents; toward the close of crystallization a filter-press mechanism became operative. The Minor Dyke Suite comprises numerous small dykes of undifferentiated dolerite. The intrusion of these dykes may be related to orogenic movements in the adjacent Andean geosyncline.

Outcrop-scale structures and magnetic fabric anisotropy of the Bomdila Gneiss (BG) that intruded the Lesser Himalayan Crystallines (LHC) of the Arunachal Lesser Himalaya are studied to understand the BG deformation history and tectonic evolution. Detailed analysis of structures reveals that the LHC have undergone three phases of deformation, D1, D2 and D3. The S2 foliation developed during the second phase of deformation (D2) is the most penetrative planar fabric in the studied rock, which shows a general ENE–WSW strike with moderate NW dip. Mesoscopic evidence of a later phase of deformation (D3) in the BG is lacking. Evidence of D3 deformation in the form of F3 folds is only observed in the adjacent metasedimentary rocks of the LHC. The magnetic foliations recorded from anisotropy of magnetic susceptibility (AMS) analysis of the BG are mostly striking NW–SE with a moderate dip towards the NE or SW, and magnetic lineation is mostly sub-horizontal and dominantly plunging towards the SE. Our study shows that the magnetic fabric of the BG does not correspond to any visible outcrop-scale mesoscale foliation. However, the magnetic foliation of the BG is parallel to the axial plane of the F3 folds of the adjacent metasedimentary rocks of the LHC. Integration of AMS and outcrop-scale structural analysis helps us envisage the superposed deformation history of the BG. Our study emphasizes the importance of AMS to detect late-stage or feeble deformation events that leave no visible outcrop-scale imprint and are difficult to discern through conventional geological means.

Summary.—(1) The reptiles Gordonia, Geikia, and Elginia are shown to be slightly later than those of the Upper Permian Pariasaurus beds of Russia, or those of the equivalent Cisticephalus zone of South Africa. They therefore represent the extreme top of the Permian. (2) The remaining Elgin reptiles are Middle Triassic (? = Lettenkohle of Germany). (3) The Elgin footprints are widely distinct from Triassic forms and from those of the Lower Permian, while agreeing exactly with the group associated with the Magnesian Limestone of England. They therefore represent the extreme top of the Permian. (4) The discovery is recorded of one of the typical footprints in close proximity with the Permian reptile quarry. (5) The Permian rocks occupy the west of the ‘Triassic’ area, the true Trias the east. (6) It is suggested that the area was a landsurface during Permian and Triassic times.

New deep seismic profiles in the southern Baltic region have failed to image the Trans-European Fault. Evidence for this structure, of suggested pre-Cadomian age, is critically re-examined. Localized geophysical anomalies are present, but these cannot be correlated with known structural features of the region. Based on the inconclusive evidence for this structure, we would therefore propose that the term ‘Trans-European Fault’ should not be used in the future, and that, to avoid confusion, authors use local names for local structures.

Graphic methods for the comparative study of numerous observations and facts have long been in use in the exact sciences. They have also been used to some extent in those branches of the descriptive sciences which deal more particularly with the problems of heredity and variation. The purpose of the present paper is to sketch in outline a way in which they may be used in the morphological and systematic study of fossils.

The shell for which I propose the above appellation was considered to be Strombus pugilis by Mr. Carrick Moore. The name was misprinted fragilis in his paper in the Journal of the Geological Society, vol. xix. p. 511. In my papers on the Tertiary fossils of Jamaica and the West Indies, the species was recorded under the name Str. pugilis. In ordinary specimens like those usually found in Jamaica, Haiti, and elsewhere, the only well-marked differences that can be noticed between the fossil shell and the recent Strombus pugilis are that in the former the last whorl is usually devoid of the spiniform tubercles, and that the shell is of shorter and broader figure. But some examples, supplied me by my friend Mr. Vendryes, exhibit an unexpected character. They show chevron-shaped bands of colour, about 12–15 on the last whorl. Each band takes the shape of a V, the apex of which occurs near the middle of the whorl, and forms an angle of about 30° pointing backwards or away from the aperture. These bands of colour are about two mm. wide and the spaces between them are about three mm. Numerous specimens of the recent Str. pugilis have passed through my hands, but I have never noticed the slightest approach to such a character. The recent shell is pale red or pink only relieved by an indistinct band of paler tint following the middle of the whorl. A less constant difference may be found in the low rounded lamellar dentition inside the outer lip which is very faint or altogether wanting in Strombus pugilis, but more marked in the fossil.

The contents of this paper record the results of a detailed examination of certain extensive areas of dolomitization in the Carboniferous Limestone of the Midlands. During the period 1912 to 1914 the faunal succession in the Carboniferous Limestone bordering the Leicestershire Coalfield chiefly claimed my attention, but many problems associated with dolomitization arose in connexion with that work and have been discussed in a previous paper. Being thus introduced to a study of metasomatism which yielded interesting results in Leicestershire, I turned my attention to the larger Carboniferous Limestone outcrop in Central Derbyshire, where a considerable thickness of dolomitized beds awaited description. The question as to whether the dolomitization in Derbyshire affected material on similar horizons or exhibited other features analogous to those of the dolomitization of the Leicestershire outcrops afforded considerable scope for investigation. Additional incentive to this particular study lay in the fact that dolomitization in the Carboniferous Limestone of this country had not been treated as a principal theme, but had been briefly described in notes occurring in papers by various authors, whose main object was the elucidation of other problems such as faunal succession.

Nine species of ostracoda belonging to the genera Eucytherura and Cytheropteron are described from the Speeton Clay at its type locality. Eight of these species are described for the first time; the ninth species is recorded for the first time from Europe.

The Late Devonian South Mountain Batholith (SMB) of southwestern Nova Scotia is the largest batholith in the Appalachian Orogen of Eastern North America and contains economic deposits of U and Sn. The SMB comprises at least 11 individual plutons, which range in composition from granodiorite to biotite monzogranite, leucomonzogranite and leucogranite. Previous studies have suggested that a combination of fractional crystallization, assimilation of Meguma Supergroup country rocks and an influx of magmatic fluids contributed to the chemical evolution of the SMB. The amount of crustal assimilation is estimated to be as high as 33%. MELTS modelling assuming a starting composition of granodiorite with H2O = 4 wt%, pressure = 4 kbar (~12 km) and fO2 = FMQ can reproduce the chemical evolution observed in the SMB. However, some leucogranites likely require an additional component (e.g. hydrothermal fluids) to explain their alkali metal enrichment (e.g. Na, K, Rb). Zircon saturation thermometry estimates indicate the Salmontail Lake and Scrag Lake granodiorite plutons had high minimum initial temperatures of 823 ± 6°C and 832 ± 2°C, respectively, which are similar to low zircon-inheritance granitoids. The TiO2/Al2O3 and alkali-lime ratios of the surrounding country rocks and the leucogranites indicate the amount of crustal assimilation is likely to be between 10% and 20%. Our findings suggest the granodiorites of the SMB were likely produced by partial melting of the sub-Meguma Supergroup (e.g. Avalon terrane) lower crust caused by the contemporaneous injection of high temperature mafic to ultramafic magmas.

Trilobites of upper Ludlow age are described from Member A of the Read Bay Formation on Cornwallis Island. Four new species are represented: Helokybe spio gen. et sp.nov. (Dechenellinae), Encrinurus hyperboreus sp. nov., Kailia? capra sp.nov. (Encrinurinae) and Hemiarges echinatus sp.nov. Other taxa present are: an effaced scutelluid; Cyphaspis sp.; a warburgelline; two more encrinurids; two other forms of Hemiarges. The trilobites occur in sediments indicative of a shallow subtidal environment, with the exception of the warburgelline which occurs in sediments deposited under deeper subtidal conditions below storm wave-base.

In a report on a visit of the Geologists' Association to the exhibits of Polyzoa and Corals in the Geological Department of the British Museum in February, 1913, the author had occasion to mention two related and unnamed species of uniserial Chalk Polyzoa that hitherto had appeared in records as Hippothoa dispersa (von Hagenow). neither of which was this species, nor did either belong to the genus Hippothoa, Lamouroux. Since one of these two forms is very common in the English Chalk and the other not rare, it is time for a description of them to be published, that collectors may have distinctive names for them. In addition, a third form that has occurred in England is described, and the rest of the species included in the genus are mentioned, so that an idea of the genus as a whole may be formed.

A prominent large negative δ13Corg excursion and a coeval notable spike in mercury (Hg)/total organic carbon ratio are observed in the middle–upper Permian Gohan Formation in central Korea, located in the eastern Sino-Korean block (SKB), which may represent the Capitanian mass extinction event. The SKB was separated from the South China block by the eastern Palaeo-Tethys Ocean. This finding from the SKB supports the widespread Hg loading to the environment emitted from the Emeishan volcanic eruptions in SW China. This study demonstrates that the Hg cycle was globally perturbed in association with global carbon cycle perturbation that occurred during the Capitanian Extinction.

Intertidal molluscs are known to occur in similar positions or zones on shores throughout the world. However, little is known about the extent to which these distributions are preserved in the fossil record. This study attempts to define the relationship to present sea level of live and dead intertidal molluscs in the Mediterranean, and utilizes this information to interpret the position at which Quaternary shorelines were formed.

The preservation of zonation patterns in the fossil record is affected by post-mortem transport, breakage and burial of the shell material. To take account of such taphonomic changes, experimental studies of shell transport and burial under waves and unidirectional currents were made, and the distribution of dead molluscs on modern shores were compared with live distributions. It proved possible to predict the frequency with which certain species were deposited on the modern shore and, by analogy, the likelihood of their preservation in the fossil record. Thus death assemblages in fossil shorelines can be accurately related to past sea levels.

An ichthyosaur in the collections of the Sedgwick Museum, Cambridge (CAMSMX.50187) was collected in the nineteenth century by the renowned fossil collector Mary Anning, but has never been adequately described in the literature. As an Anning specimen, it is certainly from the Lower Jurassic of Lyme Regis, west Dorset. The near complete presacral skeleton is lying on its left side and includes a complete skull, one complete and one partial forefin, pectoral bones, all six elements of the pelvic girdle, and both hindfins. The centra in the anterior caudal region, however, are from another individual and may have replaced the original ones. The specimen is identified as Ichthyosaurus based on the morphology of the humerus and forefin. It is assigned to I. breviceps on the basis of the relatively short snout, large eye, and tall neural spines. This is the only known specimen of I. breviceps to preserve a complete pelvis. Notably, the ilium is longer than the pubis and ischium, and the pubis is longer than the ischium. This individual is the largest I. breviceps reported in the literature, with jaw length of 33.5 cm and estimated length from snout to tail bend of 1.6 m.

Carbonatite melts derived from the mantle are enriched in CO2- and H2O-bearing fluids. This melt can metasomatize the peridotitic lithosphere and liberate a considerable amount of CO2. Experimental studies have also shown that a CO2–H2O-rich fluid can form Fe- and Mg-rich carbonate by reacting with olivine. The Sung Valley carbonatite of NE India is related to the Kerguelen plume and is characterized by rare occurrences of olivine. Our study shows that this olivine is resorbed forsterite of xenocrystic nature. This olivine bears inclusions of Fe-rich magnesite. Accessory apatite in the host carbonatite contains CO2–H2O fluid inclusions. Carbon and oxygen isotopic analyses indicate that the carbonatites are primary igneous carbonatites and are devoid of any alteration or fractionation. We envisage that the forsterite is a part of the lithospheric mantle that was reprecipitated in a carbonatite reservoir through dissolution–precipitation. Carbonation of this forsterite, during interaction between the lithospheric mantle and carbonatite melt, formed Fe-rich magnesite. CO2–H2O-rich fluid derived from the carbonatite magma and detected within accessory apatite caused this carbonation. Our study suggests that a significant amount of CO2 degassed from the mantle by carbonatitic magma can become entrapped in the lithosphere by forming Fe- and Mg-rich carbonates.

Cyclopyge genatenta Stubblefield, 1927, is interpreted from new material, and established as the type species of a new cyclopygid genus, Prospectatrix. The morphology of Prospectatrix shows that the cyclopygids and nileids are closely related, and together with the Taihungshaniidae, these families are included in an expanded concept of the Cyclopygacea. The subfamily Ellipsotaphrinae Kobayashi and Hamada, 1971 is excluded from the Cyclopygidae. Pelagic habits arose on at least five separate evolutionary lines among Ordovician trilobites: Prospectatrix lies near the origin of one of these. Cremastoglottos Whittard was derived from a robergioid ancestor by forward migration of the eyes.

Haematites of great commercial importance occur in West Cumberland, chiefly in the Carboniferous Limestone. Worked as early as the twelfth century the annual output reached half a million tons by 1861, since when the output has varied between that figure and one million tons. During these years of active exploitation many ore-bodies in the exposed ore field were worked out and active exploration is now concentrated around and to the south of Egremont, where the Carboniferous Limestone plunges beneath the New Red rocks. Among the problems confronting the searchers for new ore-bodies in this concealed ore field there is one of long standing, upon which unanimity has not been reached, namely the origin of the haematites. The question of origin is not one of mere academic interest. Its solution affords an important clue in the search for new ore-bodies. Two theories—magmatic origin and deposition from meteoric waters—are and have been propounded by rival advocates during the last fifty years. J. D. Kendall (1893) attributed the origin of the ores to ascent of magmatic solutions in pre-Permian times. To him we owe the theory of metasomatic replacement of the limestone by haematite, now generally accepted.

The Castejón-Laspaúles basin is one of the South Pyrenean basins of Late Variscan age that were strongly inverted during the Alpine compression (Late Cretaceous–Tertiary). It is mainly composed by Stephanian pyroclastic and volcanic deposits that reach a maximum thickness of ~ 500 m, and are overlain by Permian and Triassic sedimentary units. A palaeomagnetic and magnetic fabrics (AMS) study was carried out in the Stephanian units, where the general absence of flow markers at the outcrop scale and the Alpine inversional structure prevent the straightforward reconstruction of the original volcanic and basinal configuration. Magnetic fabric data are not overprinted by Alpine internal deformation and can be interpreted in terms of primary volcanic and pyroclastic fabrics. The obtained directions coincide in the different sampled units, suggesting a constant source area during the development of the basin, and show the dominance of N–S-trending K1 axes that are interpreted to be parallel to flow directions. Palaeomagnetic data indicate the presence of a pre-folding palaeomagnetic component that is rotated clockwise by an average of +37° (±32°) with regards to the Stephanian reference. This rotation probably took place during Alpine thrusting since it is also registered by the overlying Triassic deposits. The whole dataset is interpreted in terms of basin development under sinistral transtension with two main fault sets: deep-rooted E–W-striking faults, probably responsible for magmatic emissions, and shallow-rooted, listric faults of N–S orientation.

From 70 km northeast of Milford Sound (44.14° S, 168.55° E) to the coast at Milford Sound (44.53° S, 167.83° E) the trace of the Alpine Fault is nowhere more than 1.2 km from the arc with a centre at 48.81° S, 173.20° E and a radius of 628 km (5.65° latitude). Earthquake epicentres indicate that the arc defines the position of the fault just off Fiordland's outer coast and then to near the north end of Puysegur Trench at 46.9° S, 165.25° E. Along the fault vertically to a depth of 10 km the Fiordland rocks are 0.6 Mg/m3 denser than those to the northwest. Displaced post-glacial topography at and near Milford Sound shows that the dip of the fault is southeast at 75 ± 5° and that the faulting is pure dextral at a rate of at least 46 ± 5 mm/yr.

The palaeoproterozoic Svecofennian orogen in southern Finland contains a number of orogenic gold occurrences. The Jokisivu gold deposit, comprising auriferous quartz veins, is hosted by syn-tectonic quartz diorites to gabbros. Mineralization occurs in approximately WNW–ESE- and WSW–ENE-trending shear zones, which probably branch from regional-scale NW–SE-trending shears. Ore zone fabrics post-date regional-scale folding and the metamorphic peak, and can be correlated with late Svecofennian regional shear tectonics (D6; 1.83–1.78 Ga), indicating that mineralization formed during the late stages of orogenic evolution. SIMS and TIMS U–Pb dating of three samples place tight constraints on the age of gold mineralization. Zircons from both unaltered and altered quartz diorites have ages of 1884±4 Ma and 1881±3 Ma, respectively. These are interpreted as the crystallization age of the rock and as providing the maximum age for mineralization. Zircon rims from an altered quartz diorite from the ore zone give ages of c. 1802±15 Ma, which overlap with the 1801±18 Ma titanite (mean Pb–Pb) age from the ore zone. The ages are similar to the age of the pegmatite dyke that cuts the ore zone and whose zircon age of 1807±3 Ma is approximately the same as the 1791±2 Ma monazite age (TIMS) giving the minimum age of the gold mineralization. The mineralization and its structural framework can be correlated with coeval late Svecofennian shear tectonics related to WNW–ESE-oriented shortening in southern Finland. Extensive c. 1.8 Ga granite magmatism, shear zone development and associated gold mineralization are of regional importance also in the northern and western Fennoscandian Shield (Finnish Lapand and Sweden). A Cordilleran-type setting can explain the widespread distribution of magmatism and gold mineralization associated with shortening, as well as the required heat source triggering hydrothermal fluid flow along shear zones.