Some of the nodules described are similar to trace-fossils described by Donaldson and Simpson and some ichnofossils described by Seilacher, but many appear to be structures produced by sedimentary boudinage. These do not seem to be a result of organic or concretionary action. It is suggested that currents deposited thin bioclastic calcarenites with interbeds of calcite silt, and that crinoids and coral patches developed only sporadically during deposition. A few scavengers reworked the bioclastic calcarenites and calcite silt layers thus forming the trace-fossils; many of the irregular-nodules, however, were probably formed by differential compaction and segregation in the calcite silt beds, and may represent sedimentary boudins, which are relicts of former layers.

In the Kongsberg-Bamble series of South Norway leucocratic albitites are associated with amphibolites. The plagioclase of the albitites is An2-An13, that of the amphibolites is commonly An28-An40. The metamorphic facies is upper almandine amphibolite and the inferred P. T. conditions are about 700° C. and 7,000 to 8,000 bars. Recent experimental work indicates that at these temperatures and pressures amphibolites will begin to melt and the first liquid will be of albitic composition. It is suggested that the albitites owe their origin to the partial fusion of their enclosing amphibolites.

A recently computed fit of the African and South American continents is astonishingly close, apart from an overlap of some 120 miles in the vicinity of the Niger delta. This paper attempts to determine whether there is a genuine misfit at this point or whether the delta may have grown beyond the continental margin after the continents separated. The evidence suggests that final separation took place in Albian times, and that the bulge of the present continental edge into the Atlantic Ocean has resulted from post-Cretaceous development of the delta. The gross structure of the delta region and also the associated minor structures are considered to represent a passive response to the influx of sediment from the Niger River.

Phlogopite-spinel-bronzite rocks, in which aggregates of bronzite and sapphirine appear to be pseudomorphs of aluminous anthophyllite, occur in a restricted low-granulite terrain in the Strangways Range, central Australia. The form of the postulated reaction is gedrite + ΔH = enstatite + sapphirine + silica + escaping “ water ”.

Recent studies of the effects of folding on the orientation of primary sedimentary lineations have been restricted to cylindrical folds. This work is now extended to include conical folds.

A flora of cuticle fragments obtained by maceration of the Bathonian coal of Brora is described together with some lycopod megaspores from the shale below the coal. All the species are known from the Bajocian or Bathonian of N. Yorkshire. Ptero-phyllum cycadites sp. nov. is described as new, the type being a Yorkshire specimen. The formation of the Brora coal is discussed.

The directions of magnetization of samples from two sites in the Devonian Ashprington Volcanic Series, Devonshire, are similar in spite of the difference in the dip of the lavas. They are close to the mean direction for the Keuper Marls and it is concluded that they resulted from remagnetization of the lavas during the Triassic.

The traditional concept of contraction crack formation is based on a model having a regular arrangement of stress centres. A more realistic result is produced if the model consists of a close random packing of stress circles; this gives a crack configuration very close to that observed in real basalt flows.

The contact relationships of the Fault-Intrusion are described, in detail, from the type locality. Textural and mineralogical evidence indicates that the fine-grained marginal facies of the Fault-Intrusion is not a priori evidence for magmatic emplacement. The production of “ flinty crush-rock ” from brecciated quartzites downfaulted within the Glencoe cauldron is described from the south-western inner contact, and is shown to be a result of gas attrition. “ Flinty crush-rock ” is recorded for the first time from the north-eastern contact with the country rocks outwith the cauldron, separated from the latter by a sheared microbreccia not found at the inner contact. The contact relations of the Fault-Intrusion with these “ flinty crush-rocks ”, more properly termed pseudotachylites, indicates that the Fault-Intrusion was emplaced as an entrained fluidized system of gas, solid phenocrysts and, probably, liquid droplets. The production of the sheared microbreccia at the outer contact is thought to be due to shearing stresses exerted by the entrained system on the heated wall-rocks.

A small mass consisting of three intrusions of fine-textured acid rocks occurs within the basaltic agglomerates of the Kilchrist Vent of Tertiary age. One of the intrusions comprises flow-layered rhyolite and ignimbrite. It is thought that the rock-types represent two distinctive eruptive waves. A form of ovoidal structure not seen elsewhere in the Kilchrist area occurs in another rhyolite intrusion.

Bedding mullions have been produced by compression parallel to bedding in the hinge region of a large recumbent fold. Geometrically, the mullions are a combination of parasitic folding, with characteristic gadrooned profile, and cleavage planes. The cleavage is not an axial plane structure, but where fully developed produces a perfect slate fabric in rocks of appropriate lithology. The mullions are found on both sides of a bed of inferior slate sandwiched between two beds of good roofing slate. Boudinage structure results where the mullions are exactly back to back, and the planes of separation provided by the cleavage are infilled with coarse calcite. The slates are interbedded and interlaminated with limestone.

Such boudins are unusual in that they occupy the hinge region of a fold and result from compression parallel, rather than at right angles, to the bedding.

A new description of “Didymograptus” fasciculatus Nicholson, 1869, is given on the basis of specimens from the Skiddaw Slates (Zone of Didymograptus bifidus) some of which are preserved in relief. The uniramous rhabdosomal form is confirmed. The presence of prothecal folds indicates that the species belongs in the family Sinograptidae Mu, 1957, and adoption of the generic name Nicholsonograptus, proposed by Bouček and Přibyl (1951) with “ D. ” fasciculatus as the type species, is recommended. The possibility that Nicholsonograptus fasciculatus is an intraspecific variant of Holmograptus lentus (Törnquist, 1911) is discussed.

Chemical analyses of dolerites and metadolerites from the Scourie-Loch Laxford area have been made, together with analyses of amphiboles and a pyroxene from these rocks.

Chemical variation within the dykes as originally emplaced has been investigated. Introduction of material during metamorphism is limited, only potassium showing a marked increase in concentration. In the least-altered dykes a relationship between degree of clouding in felspar and amount of H2O+ present is indicated.

Chemical analyses and optical properties of amphiboles show no distinctive trends which could be associated with the progress of the metamorphism.

A new species of Minnivola is described, from late Miocene lime-stone occurring in the valley of the Umfolosi River in Zululand, South Africa. The species extends the known range of the genus into the East African region and is distinguished by the presence on the adult right valve of about thirty-two ridges arranged in bundles of four, with prominent grooves between the bundles.

Microscope studies of a flattened fold are consistent with conclusions from macroscopic observations that whereas mudstone cleavage development may have resulted from a laminar-type flow governed by competent confining sandstone beds, the sandstone cleavage appears to be related to the dilation of texture during the early stages of deformation. Continued deformation results in a textural disruption of the initially competent sandstone, which is considered to allow flattening.

A spiral brachidium has been discovered in the Lower Jurassic brachiopod Cadomella, which is generally regarded as the last representative of the Chonetidina. Cadomella is transferred to the Koninckinidae, which are considered to be spire-bearing Chonetidina rather than aberrant Spiriferida. This interpretation implies another independent evolution of spiralia within the Brachiopoda.

Structures in the Upper Purbeck Beds at Peveril Point, Swanage, Dorset, are described. Interpretation of the overall structural pattern has been attempted by constructing a three-dimensional model of the Broken Shell Limestone surface, upon which the more complex folding of the shales and marbles has taken place. The regional setting of the structures is discussed.

At Uloa in Zululand a nodule bed is the basal formation of a thin group of Tertiary sediments that rests on nearly horizontal Senonian silty mudstones. It contains mammillary, botryoidal, and cylindrical nodules, remanié Lower and Upper Cretaceous mollusca all ferruginized and partly pyritized, silicified Cretaceous wood, worn Tertiary sharks' teeth, and cetacean bone, phosphatized nodules of both Upper Cretaceous and Victoriella-bearing Eocene, and Tertiary glauconitic sandstone pebbles dated at 55 million years.

A coquina-like limestone (“Pecten Bed”) overlies the irregular upper surface of the nodule bed disconformably. Consideration of some of the megafossils, the absence of larger Foraminifera, and the presence of Orbulina universa suggest that the “Pecten Bed” is Middle to Upper Miocene in age.

Alternations of coarse and fine grained calcarenite layers that overlie the “Pecten Bed” disconformably, may be of youngest Miocene age.

The nature of the Tertiary rocks suggests shallow water sedimentation from the Eocene to latest Miocene, with several periods of transgression and regression, and slight epeirogenic or eustatic movement only.

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.

The mineral cordierite occurs in Pre-Cambrian gneisses, granulites, and granites of the Guyana Shield in British Guiana. In the Acid Biotite Gneisses and Acid Granulites forming the Kanuku Group, the mineral was formed during regional metamorphism. Considerable enrichment of cordierite occurs in the contact aureole around the South Savanna Granite. Cordierite of xenocrystal origin also occurs in the South Savanna Granite and its apophyses. The 2V and optic sign of the mineral varies widely, and no definite pattern in relation to the paragenesis of the mineral is recognized. Untwinned cordierites are predominant in regionally metamorphosed rocks while lamellar, interpenetration and sector twins are characteristic of cordierites in contact hornfelsed aureole rocks.