The petrography of the greywackes is described, with special emphasis on rock and mineral grains indicative of provenance. Sedimentary structures are discussed, and current directions based on flute cast measurements are recorded. The stratigraphy and palaeontology of the Denbigh Grits, and the facies of other parts of the Wenlock in the Welsh area are also considered. It is concluded that the greywackes were derived from an area of Pre-Cambrian rocks near south-west Wales and that they were transported along the axes of subsiding troughs by turbidity currents.

The succession in the Upper Dalradian is described. The author follows Anderson in correlating the Leny and Ben Ledi Grits. Way-up evidence indicates that the Leny Limestone does not occupy a syncline as previously supposed, but is a stratigraphical intercalation in the Leny Grits. It is shown from way-up evidence and structural analysis that the Aberfoyle Anticline closes downwards and is a synform.

An investigation of the sequence of microspores vertically within a number of seams containing horizons of crassidurite has revealed a succession of three distinct phases, each characterized in the main by the dominance of one of the three genera Lycospora, Laevigato-sporites, and Densosporites, The succession begins with the Lycospore phase and culminates in the crassidurite with the Densospore phase. The significance of this succession in relation to the formation of crassidurite and the provenance of Densospores is discussed.

The distribution and form of the products of migmatization in the area are described and the close relationship between migmatization and folding in time and space is demonstrated. Synoptic diagrams of the linear structural elements for various parts of the area are given. The sheaves of β-axes, small folds and lineations widen with increase in migmatization, presumably due to increasing mobility of the rocks during the migmatization process.

The great majority of Moine lineations are mica structures, and together with a parallel preferred orientation of epidote [010]-axes, are directed mainly into the south-east quadrant. This orientation is retained within the crush zone alongside the Moine Thrust. The regional preferred orientation of muscovite [100]-axes and [001]-axes is consistent with north-east and south-west movements except within the crush zone where fabric reorientation suggests movements normal to this direction. The growth of albite textures and fabric is intimately associated with thrust plane movements, the preferred orientation of albite suggesting a south-east and north-west vertical plane of deformation.

The paper refers to a number of areas in which the lineations are related to major folds. It shows that the shapes of individual folds, the interference of neighbouring folds, and the imposition of a second generation of folds all influence the arrangement of linear structures and that lineation maps may only become explicable when the major structure has been determined.

The directions of the natural remanent magnetization of samples collected from dykes on Lundy have been measured and related to those of Tertiary lava flows in Northern Britain. Evidence is given suggesting that the dykes are Tertiary and pre-Upper Oligocene in age, and that the geomagnetic field was reversed at the time of their intrusion.

This note records a unique instance of rhythmic layering which is likely to have an important bearing on the interpretation of such layering in general.

The superfamily Lichacea is here considered to include two families : the Lichidae, composed of four subfamilies and twenty-four genera, and the Lichakephalidae, comprising only one species. Reed's interpretation of the glabellar and occipital lobes in the Lichidae is considered to be correct; the definition and degree of fusion of these lobes is the main criterion of generic discrimination. Hypostomal features are of assistance in defining subfamilies. The characters of the pygidium are constant in some genera, but unstable in others. The Lichinae and Homolichinae, stratigraphically the oldest subfamilies of the Lichidae, are chiefly European in occurrence during the Ordovician period. The Tetralichinae and the Ceratarginae occur earlier in North America than in Europe. Lichakephalus occurs in Lower Tremadoc beds of Bavaria.

The “space problem” in north-west Donegal is analysed; structures of country rocks and granite-quartzite contacts, together with marginal granitization, suggest that two space-forming processes operated together. The inter-relationship of these mechanical and chemical processes in Gweedore and Cloghaneely suggests a dual rhythm within Read's (1949) granite series.

Remapping of parts of the Galway granite has shown that over most of its outcrop it is a homogeneous adamellite. A steeply dipping belt of basic rocks borders the intrusion on the north where there is a reaction zone between adamellite and basic rock. A similar but gently dipping belt of basic rocks overlies the granite to the west. In the south, where there is no reaction zone, the granite intrudes and hornfelses a group of pillow lavas, greywackes, and conglomerates. The structural features of the northern border indicate that the granite has been emplaced as a diapir and radial fractures in the north-east border further indicate that the granite and its basic envelope moved upward and outward together into the Connemara schists.

Five species of Ordovician Bryozoa are redescribed, based on the type specimens of Lonsdale (in Murchison, 1839: “Favosites fibrosa” (1843: “Ptilodichtya” dichotoma), Phillips (1848: “Favosites” favulosa), and McCoy (1850: “Nebulipora lens” and “Ptilodichtya explanata”). Six other species are discussed and some of them figured, but the preservation of the material does not allow a complete redescription of them.

The Lower Hecla Hpek rocks of Ny Friesland are described petrographically, and evidence is presented relating to some granitic rocks in this group whose mode of origin is uncertain.

The erratic rocks of the early pebble gravels are similar to those of the Oxford plateau drift, and reasons are given for concluding that they belong to the drifts of the proto-Thames, and are earlier than the southward diversion of that river by an advancing ice-sheet. Comparisons with the constituents of the later deposits of the Clacton channel are also discussed.

Material belonging to the genus Salterolithus has been examined from Trilobite Dingle, Welshpool, and it is found that S. caractaci and S. intermedius (Wade 1911) are conspecific, the older name taking priority. Trilobite Dingle is the type locality for S. intermedius and also for the restricted species caractaci. A new variety is established for the forms occurring slightly higher in the sequence than S. caractaci.

In the later growth stages of Palaeosmilia, minor septa are inserted simultaneously on both sides of each newly added major septum and they originate high up near the growing crest of this major septum. Thus, a minor septum occupies the interseptal space in which the next major septum will be inserted. The next major septum develops directly upon the axial edge of this minor septum and it originates deep down in the calyx. The similarity is pointed out between the septal insertion in Palaeosmilia and in the more typical aulophyllid (clisiophyllid) corals.

Optical and chemical data are presented on the clinopyroxenes (titaniferous salites) from a differentiated teschenite sill. The range of clinopyroxene composition is close to the limits, Ca49Mg37Fe14 to Ca47Mg33Fe20. Attention is directed to the clinopyroxene compositions and zoning in their relation to the parent rocks and associated minerals.

The erratics, weathering and surface relief of the Taele gravel south of Thriplow point to its being immediately post-Gipping (Saale) in age. On the other hand, its molluscan fauna is of a type usually considered to be characteristic of cold conditions associated with the last glaciation. It is concluded that this fauna is characteristic of a certain type of local conditions and not of a definite period in the Pleistocene.

Large, individual olivine crystals exhibiting a banded structure are described from olivine-basalts from a number of localities in the Carboniferous lavas of the Midland Valley. This structure is of deformational nature and provides what seems to be a sound criterion for distinguishing between phenocrystic and xenocrystic olivine in olivine-basalts.

An outline of the geology of the Dardanelles is presented. Metasediments, chiefly marbles and schists, are cut by a granite and covered unconformably by Tertiary strata which include both sediments and volcanics. The Dardanelles is considered to be a drowned fault valley and in the south an echelon fault system is described.