Lepidostrobus fimbriatus Kidston is redescribed as Lepidostrobophyllum fimbriatum (Kidston) from a new locality, in the Drybrook Sandstone of the Forest of Dean. The sporophyll consists of two parts bent at right angles, forming a heel of hard tissue. The sporangium is attached to a small area by the midrib, and is only partly occupied by the four spiney megaspores. A ligule is present.

Alkaline and ultramafic lamprophyre dykes at Aillik Bay on the coast of central Labrador exhibit features indicative of volatile-rich conditions at the time of emplacement. Aillikites (ultramafic lamprophyres) are flanked by closely spaced fracture systems whose formation was promoted by a carbonate-rich fluid moving ahead of the intruding magma. Sannaites (alkaline lamprophyres) frequently have horned termination structures which are interpreted to be partial reconnections between dyke segments which had separated at an earlier stage of intrusion.

The lamprophyre dykes comprise three sets which are interpreted as cone sheets and radial dykes related to an intrusive centre located beneath the Labrador Sea to the northeast of the coastal exposures. This complex is one of several on the margins of the Labrador Sea, and its position may be influenced by the Archean/Aphebian boundary and by a major oceanic structural feature represented by offsets in seafloor magnetic anomalies.

The now well-known Liassic Acipenseroid fish Chondrosteus acipenseroides was named by Agassiz in 1843, but not described by him. It subsequently formed the subject of an elaborate memoir by Sir Philip Grey-Egerton, Bart., in which, besides giving a minute account of the structure of the genus, he named two additional species—C. pachyurus and C. crassior. Putting the results of Sir Philip's investigations as briefly as possible, he maintained that while “in all essential points” Chondrosteus resembled the recent Sturgeon, nevertheless in certain others, and notably in the structure of the opercular and hyoid regions, it constituted a transitional form towards the more ordinary Ganoids. Moreover, the skin of the body presented the same naked condition seen in the recent Polyodon.

Upper Jurassic faunas from Wadi Hathira (Kurnub Anticline), Southern Israel, are listed and allocated to the Callovian, Lower Oxfordian, Argovian, and Sequanian.

That many of the Palaeozoic limestones are more or less exten sively composed of the skeletons of various Invertebrate animals, sometimes in a perfect condition, sometimes more or less largely fragmentary, has long been known.incertain instances a microscopic investigation of these ancient calcareous sediments may fail to demonstrate the presence of organic remains, or may reveal but few of these. Thus there occur beds of lithographic limestone in the Palceozoic series which would seem to be simply of the nature of very finely levigated calcareous mud, the component grains of which were, however, doubtless derived, in the first instance, from the calcareous skeletons of animals.

The existence of the Crossopterygian fish Eusthenopteron in the Old Red Sandstone of the Moray Firth area has been recorded recently by the writer (Westoll, 1937). Since that time new material has been found in the collections of the Royal Scottish Museum; the specimens comprise a “parietal” shield and other remains from Boghole, and an imperfect “fronto-ethmoid” shield, of which the provenance is unknown. Dr. A. G. Stephen, of the Royal Scottish Museum, has been most kind in allowing the writer to study this and other comparative material.

A structural study of rocks of the Hecla Hook formation in the area of Forlandsundet of Vestspitsbergen reveals the presence of two B–axes. The earlier (B1) trends roughly east–west and affects only the Hecla Hook formation; the later axis (B2) trends roughly north–south, and affects also rocks of Carboniferous age. It is suggested that B1 is the main “Caledonian” axis in this area, and that B2 and the roughly north–south “grain” of the rocks concerned are Lower Tertiary phenomena.

The olivine-rich rocks have acquired a particular significance in petrogenetic discussions as a result of the growth ofthe realization of the difficulties involved in postulating the existence of anhydrous melts of corresponding composition.The belief that such rocks have originated through the local accumulation of olivine crystals, without significant remelting (Bowen, 2, p. 108; 3, pp. 133–174)1 has received added support from the experimental determination ofthe melting relationships of the olivines. The facts “seem susceptible of no other interpretation than that, when such masses become rich in olivine, they do so through the accumulation of crystals of that mineral, which remain as such and do not become a part of the liquid by remelting or re-solution” (4, pp. 394–5).

The very numerous Tertiary dykes of the Clyde islands (Arran, Bute, and the Cumbraes), and of the adjacent mainland and peninsulas, have been little studied either from the geological or petrographical point of view; but they are of great interest, not only in themselves, but as providing a link between the dykes of the better known areas of the North of England, and of Skye and Mull. The material is not yet gathered on which could be based a complete account of the series. The present paper is designed to present a full description of a hitherto unrecognized type of Tertiary dyke, typically exposed in the Great Cumbrae, and to indicate its relationships to other types already described from Mull and the North of England. Furthermore, a few other dykes from the Clyde area, all of basaltic composition, will be briefly described.

Petrofabric analyses of marble specimens from three widely separated localities in Mid-Strathspey and Strathavon are recorded. Preferred orientation of [0001] in the constituent grains of calcite conforms to a B-tectonite pattern, the symmetry axis (B) of which coincides with the b axis of the megascopic fabric (lineation and fold axis) at each locality. Development of {011¯2} lamellae in calcite grains is attributed to late minor compression, the direction of which is more or less horizontal and trends between N.E.–S.W. and E.N.E.–W.S.W.

The Quaternary deposits of the Fenland, consisting of silts, clays, and peats, offer several problems of correlation. Large exposures of these beds have been rare, and hitherto no attempt at dating individual beds has been made, although from the descriptive point of view the whole of the Fenland deposits were dealt with very fully by Skertchley in 1877 (1).

Investigations of the sedimentary rocks of the Umkondo System have enabled six zones of eastwardly increasing metamorphic grade to be delineated on the basis of index mineral assemblages in pelite horizons.

Chlorite, garnet (almandine), staurolite, kyanite, and sillimanite isograds have been recognized over a distance of 500 km. along the eastern border of Southern Rhodesia and are plotted on a map. More detailed reconnaissance work has been confined to the Barué highlands north-east of Inyanga. In addition, a “zone of intermediate isotopic age measurements” is proposed to the west of the lowermost chlorite zone. The isograds lie parallel to the structural edge of the north-south trending Mozambique orogenic belt and can be joined with those of similar metamorphic rocks in the east-west trending Zambesi orogenic belt, suggesting contemporaneity of the c. 500 m.y. regional tectono-thermal event in these two belts.

The Orlock Bridge Fault separates the Ordovician and Silurian turbidite sequences within the Southern Uplands thrust belt. A large biostratigraphical break and the 1 km wide sinistral Slieve Glah Shear Zone associated with the fault in northern Ireland led to previous interpretation as a major regional structure, possibly a terrane boundary. In Scotland, however, the stratigraphical break is much less and an association with inliers of the Moffat Shale Group suggests that the fault is essentially similar to the other tract-bounding faults which originated as syn-D1 thrusts within the imbricate stack. Localized sinistral deformation apparent along the trace of the Orlock Bridge Fault in southwestern Scotland, associated with post-1 reactivation, is comparable to that seen at Slieve Glah. Further east, a broad zone (up to 8 km) of sinistral ductile deformation, the Moniaive Shear Zone, is recognized adjacent to the Orlock Bridge Fault over a strike length of about 100 km. However, this zone differs from the Slieve Glah Shear Zone in its width and its location relative to the fault, suggesting that it is not simply related to the fault but represents a more regional deformation. Sinistral reactivation of the Orlock Bridge Fault was possibly initiated in the Wenlock during the peak of sinistral shear at the thrust front, although it may have developed over a long time contemporaneously with, but locally post-dating, the Moniaive Shear Zone. The latter deforms porphyroblasts with the thermal aureole of the c. 392 Ma Cairnsmore of Fleet granite pluton, which was emplaced into and largely post-dates the shear zone, but is deformed by the Orlock Bridge Fault. Major dip-slip reactivation of the fault post-dates the Moniaive Shear Zone and regional metamorphism and probably occurred in the Carboniferous or Permian. There is some evidence for a deep crustal feature coincident with the Orlock Bridge Fault, possibly the boundary between different crustal blocks in the collage of terrane fragments accreted during the final closure of Iapetus, which may explain the unusual extent of the reactivation of the Orlock Bridge Fault within the allochthonous Southern Uplands thrust stack. However, the situation of the fault within the Southern Uplands terrane and, in Scotland, the biostratigraphical evidence of no major stratigraphical break across the fault and the lack of any clear relationship between the Orlock Bridge Fault and the Moniaive Shear Zone indicate that the fault should not be regarded as a terrane boundary.

The dolerite and basalt intrusions within the Lower Palaeozoic sequence of northwest Wales are largely restricted to the outcrop of Ordovician strata. Their distribution and close association with known volcano-tectonic structures were controlled by a tectonic framework of deep-seated fractures. In central and northern Snowdonia, volcanism during Caradoc times was related to the evolution of a fracture-controlled trough. An increase in the extensional stress across the trough with time is reflected in the progressive increase in basaltic magma movement during the volcanic cycle. The trough represents an attempted rift in the lithospheric plate, which failed to create an ocean basin and was subsequently aborted.

Rubidium–strontium and potassium–argon measurements on Lewisian intrusive rocks, considered to be late Scourian in age on general geological grounds, have indeed yielded dates in the range 2450–2600 m.y. This demonstrates that rocks of Scourian age that have escaped substantial Laxfordian reworking are preserved in the Eastern Gneisses of Barra. The relevant geological consequences and correlations are briefly discussed. A cross-cutting late pegmatite yields a typical Laxfordian date of 1679 m.y.

The accompanying Plate represents a restoration of the skeleton of Hippopotamus minutus, Blain., which has lately been completed in the Geological Department of the British Museum (Nat. Hist.). The vertebral column and limbs are almost entirely composed of the actual bones, while the model of the skull has been built up according to the various parts obtained separately. No ribs were preserved in their entirety, neither were perfect specimens of the scapulæ or innominate bones procured. A large amount of material, including that from which the reconstruction of this skeleton has been made, was brought from Cyprus as the result of excavations carried on there by me at different times in 1901–2. The specimen was mounted and the skull modelled with great skill by Mr. P. O. Barlow, Formatore in the British Museum (Nat. Hist.).

The plutonic crustal sequence exposed northeast of Sabzevar is part of the ophiolitic belt of Sabzevar that occurs along the northern margin of the Central Iran micro-continent. The sequence includes olivine and pyroxene gabbro with cumulate characteristics, isotropic gabbro, foliated gabbro and a diabase sheeted dyke complex cut by wehrlite and olivine websterite intrusions, and pegmatite gabbro and plagiogranite as small intrusions and dykes. The sequence is comparable to gabbros in known ophiolite complexes. Microscopic studies show an abundance of the mesocumulate and heteradcumulate textures that represent open system magma chambers, which are common in supra-subduction zones. The olivine → plagioclase → clinopyroxene → ± orthopyroxene → amphibole trend of mineralization in the gabbros, similar to mid-ocean ridge basalt (MORB), and olivine → clinopyroxene → ± orthopyroxene → plagioclase → amphibole, similar to arc rocks, indicate the diversity in the formation of these rocks, and represent petrographic evidence of their formation in a supra-subduction zone. The rocks have calc-alkaline to tholeiitic affinities, and niobium depletion in the spider diagrams of diabase that matches the patterns of island arc magma. These patterns, and the light rare earth element enrichment of the diabase and plagiogranite, suggest the effect and introduction of the fluids, originating from the subducting slab, beneath the mantle wedge. The low titanium compositions, matching those of arc diabase and plagiogranite, plot in the island arc to MORB tectonomagmatic fields, and suggest formation of the Sabzevar ophiolitic plutonic crustal sequence in a supra-subduction zone during Late Cretaceous time.

3D modelling of geological structures is a key method to improve the understanding of the geological history of an area, and to serve as a drive for exploration. Geomodelling has been performed on a large 60000 km2 area of the Zagros fold-and-thrust belt of Iran, to reconcile a vast but heterogeneous dataset. Topography, geological surface data and dips, outcrop surveys, and well and seismic data were integrated into the model. The method was to construct a key surface maximizing the hard data constraints. The Oligo-Miocene Top Asmari layer was chosen, as this formation was regionally deposited before the main Zagros collision phase and because the numerous outcrops allow proper control of the bed geometry in the fold cores. Interpreted seismic data have been integrated to interpolate the surfaces at depth within the synclines. Several conceptual models of fold geometry have been applied to estimate the best way to convert seismic time signal to depth. Several deeper horizons down to Palaeozoic strata were deduced from this key horizon by applying palaeo-thickness maps. During the construction, the 3D interpolated surfaces could be reconverted to time, using a velocity model, and compared with previous seismic interpretations. This exercise obliged us to revise some early interpretations of seismic lines that were badly tied to wells. The 3D modelling therefore clearly improves regional interpretation. In addition, the 3D model is the only tool that allows drawing consistent cross-sections in areas where there are no seismic lines. Emerging Hormuz salt diapirs were added to the model. Dimensions and shapes of the individual diapirs were modelled using a statistical survey on the cropping out Hormuz structures. Modelling reliably demonstrated that the diapirs, when piercing, show a constant mushroom shape whose diameter depends on the stratigraphic depth of observation. This observation allowed us to exemplify relations between the pre-existing diapirs and the anticlines of the area, and to highlight the morphological changes from the inner onshore areas to the coastal and offshore areas. In addition, one of the surprising results of this study was the observation of the increasing diameter of the diapirs at the time of the Zagros collision and folding event, with growth strata and overhangs on the flanks of the diapirs.

During the past two years several core-borings have been put down in South Durham in order to prove extensions of the Productive Coal Measures. In passing through the cover of Magnesian Limestone, here up to 300 feet thick, quite the most arresting feature was the presence of innumerable cavities of irregular distribution. These are especially characteristic of the Lower Limestones, and are of all sizes from tiny geodes almost completely infilled with calcite to gashes which cut deep into the heart of the 6 in. core. They are usually lined with calcite in a variety of forms; far more rarely there are other minerals among which fluorite and barytes seem to be the most abundant.