Pillows are described in various stages of production from small parent lava flows. The lavas flowed into water–laden sediments down to depths at which the latter were capable of supporting the weight of lava. Because of their lack of systematic relationship to tectonic axes, certain structures observed in these sediments are interpreted as pushing folds induced by the “intrusion” of lava flows. The direction of flow of the lavas was towards the north.

A layer of massive and lineated hornblende-biotite-gneiss has fractured along ac-joints (perpendicular to the layering and b–lineation), at regular intervals along its lower surface in contact with a thin marble bed. The joints have been opened from below and the marble has penetrated upwards to form intrusive tongues caused by extremely plastic flow folding, as shown by the unbroken banding in the marble. The structure constitutes a variety of one-sided boudinage involving segmentation in the lowest metre or so of the hornblendic rock, while the extreme marble deformation is all accommodated in a few centimetres thickness. The structures must have developed at relatively high temperatures to allow contemporaneous segregation of quartz-feldspar pegmatite veins from the hornblendic rock, and of diopside reaction skarns at the marble junctions.

Correlation of the metamorphic inlier of Co. Tyrone with the Connemara Schists, together with a reinterpretation of the"Tyrone Igneous Series" erected by J. J. Hartley, lends support to recent suggestions that the Highland Boundary Fault originated as a normal fault with downthrow to the north. The palaeogeographical implications of this are briefly discussed.

Observations have shown that some garnets in the micaceous schists of the Chor area, Himachal Pradesh, India, still retain the continuity between the Se and Si planes. The Se and Si surfaces are continuous surfaces and not merely statistical as has been assumed by some.

At a late stage of folding, strain slip cleavage was imposed on the pelitic sediments of the Ordovician greywacke-slate association in Central Victoria. The nature of the cleavage surfaces was controlled by the type of sediment in which they were developed. In the coarser siltstones, and in the interlaminated zone of oscillatory graded beds, they are second order shear zones. In the finer siltstones and slates they are thin continuous shear domains of the first order.

A re-interpretation of the Ben Lui Fold (and its equivalents) is suggested on the basis of correlating the structures in the South-West Highlands (Roberts, 1963) with those in Upper Glen Lyon (Treagus, in preparation) and the Tummel (Sturt, 1961) and Blair Atholl (Harris, 1963) districts. In all these districts the Cowal-Loch Tay flat belt and the steep belt to its north-west define a structure previously interpreted as the hinge of the primary and recumbent Ben Lui Syncline. As primary structures are themselves folded round this hinge, and as minor secondary structures are congruent with it, the authors interpret the Ben Lui Fold as a secondary structure.

Seven occurrences of tonsteins are recorded, five from the South Staffordshire Coalfield (Westphalian C), one from Yorkshire (Westphalian A), and one from South Wales (? Westphalian D).

Most of the cross-bedding in the Central Pennine Millstone Grit occurs in the coarse sandstones and indicates that they are probably fluvial in origin. The cross-bedding often occurs within sheets of sandstone, and it is suggested that each sheet was deposited during one episode of flooding. Medium-grained arenaceous rocks show other varieties of cross-bedding that could have been formed on tidal flats, but this evidence is inconclusive.

The stratigraphy of the Lower and Middle Jurassic rocks of the Hebrides is briefly summarized, and the lithostratigraphical nomenclature reviewed. To replace the inappropriate name “Inferior Oolite” for the lower marine part of the Middle Jurassic a new name, Bearreraig Sandstone Series, is proposed. This series is defined, and the succession at the type section is summarized.

X-ray analyses of Kimmeridgian clays recovered from the Warlingham Number 1 Borehole indicate that illite and kaolinite are the dominant clay minerals present. Illite, chlorite, and kaolinite, are present in the Devonian clays recovered from the Willesden Number 1 Borehole. The relationships between the clay minerals of the Kimmeridgian and Devonian clays and the clay mineral assemblage of the English Wealden is discussed.

Textural differences in the occurrence of microcline define augen gneisses, subhedral porphyroblastic gneisses and euhedral porphyroblastic gneisses within the Bartica Assemblage, British Guiana. The introduction of microcline is metasomatic and the nature of the porphyroblasts appears to be a reflection of tectonic control during their development.

Basalt groundmass textural nomenclature is reviewed and revised. The intergranular and ophitic extures are seen as end members of a series with steadily increasing grain-size, the international representative of which is here termed the “isogranular” texture. Undere intrusive conditions the series may be extended to include the poikilitic texture. Ophitic texture is regarded as an intergrowth;the term “sub-ophitic”s not suitable for basalts but may be retained for texturally isotropic rocks. When basalts cool hurriedly they will tend to develop an intergranular texture whereas extension of the crystallization period permits the formation of an ophitic texture. Cooling conditions will be determined by a combination of the effects of the volatile concentration and the flow characteristics, the latter partly depending on topography.

The nepheline syenites of Koraput, Orissa, in eastern India, are described for the first time with mineralogical details. The major rock type is a hypersolvus nepheline syenite. The mafic minerals are iron-rich biotite and subordinate alkali ferrohastingsite, the latter coexisting with titanomagnetite. The crystallization history of the magma has been interpreted in the light of chemical data on the rock and coexisting nepheline and alkali feldspar.