The eastern limit of a narrow belt of rocks, running from Co. Antrim through Cowal and into Perthshire, containing abundant albite porphyroblasts, has been mapped in detail. Albite is shown to have recrystallized as large porphyroblasts (up to 23 mm. in diameter in some cases) after the last main phase of deformation affecting these rocks. It is concluded that a large scale, late stage, regional metasomatism in the metamorphic history of the rocks of this area was the causal mechanism of the growth of albite porphyroblasts.

Evidence is presented which shows that nepheline develops a preferred c-axis orientation in response to deformative stresses. It is believed that this is the first record of a stress-induced preferred orientation of nepheline.

Three camerate crinoids, Thylacocrinus(?) ignotus sp. nov., Eucalyptocrinites inchoatus sp. nov. and Hexacrinites(?) sp. are described from the lower Devonian of Toongabbie, Gippsland, Victoria, Australia.

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.

The species Alveolites fibrosa Lonsdale, 1839, described also as Stenopora fibrosa var. β Regularis McCoy, 1851, and referred to as Stenopora fibrosa var. incrustans McCoy, was recognized originally by Lonsdale (1839) as different from Calamopora fibrosa Goldfuss, 1826. It is described here as Orbignyella fibrosa (Lonsdale) and shown to occur typically in beds of Leintwardine age.

The discovery of trilobites characteristic of the Gattendorfia Zone is described from the California Quarry, Boscastle. The possible stratigraphical implications are discussed and a comparison is made with beds of similar age at Launceston. It is suggested that there is no important stratigraphical break at the top of the Devonian and that there is a conformable passage from the Tintagel Volcanic Series into the Carboniferous. The Tredorn Phyllites are tentatively equated with the Woolgarden Phyllites. There is no evidence to support the contention that the Lower Culm contains an important greywacke sequence; these beds are probably of Upper Culm age.

Recent studies concerned with the application of rock magnetism to several geological problems serve to illustrate the scope of the methods at present available. Rock magnetism can usefully be applied to determine the age of a rock or to correlate it with some other. It may be used in studying the structural history of a formation or the thermal history of a rock. The examples cited deal with igneous rocks in Britain, but the methods also apply to some sediments, and possibly to metamorphic rocks.

It is stressed that rock magnetism can be applied quite independently of any theory concerning the earth's field. It is necessary only to establish whether the magnetism measured in the laboratory is a true record of that acquired when the rock formed, or at some other known time in its history.

Regional variations in modal analyses of the Chandos Lake pluton (Ontario) and the Beinn an Dubhaich granite are compared. Trend surface analysis maps for the latter area show a southwest “grain” parallel to the axis about which King (1960) suggested the sheet of granite is folded. The modal data thus appear to confirm King's hypothesis, and to indicate a more mafic base and increase in quartz content upwards through the sheet. The value to petrogenesis of quantitative variation studies of rock masses is briefly discussed.

Some closed basins extending along the strike of soft rocks in the English and Bristol Channels were cut by sand moved by tidal currents.

PT curves for the beginning of melting of five analysed shales in the presence of water vapour under pressure are 20° C. to 40° C. higher than the corresponding curve for granite. About 150° C. above the beginning of melting, the shales are half-melted; this is higher than the liquidus curve of most granites. Refractive indices of the quenched liquids (1·495–1·505) indicate a granitic or granodioritic composition. Quartz, cordierite, mullite, hypersthene, anorthite, etc., are developed in the partially fused shales. Partial fusion of shales by a granitic magma, even if superheated, would produce a liquid no more basic than granodiorite. The chemical characteristics of the shales are compared with average igneous rocks, and there appears to be no possibility that fusion of shales could produce a basaltic magma. Complete fusion would produce a melt with composition distinct from normal igneous magmas.

An unusual fayalite-bearing quartz-monzonite occurs around Bauchi in Northern Nigeria and is distinguished from the high-level fayalite granites of the Newer Granites ring complexes by the presence of a linear structure conformable with those in the surrounding rocks, the gradational nature of its contacts, the extreme coarseness of its mineral constituents and the abundance of myrmekite. It is similar to them in its distinctive green colour and in the high FeO: Fe2O3 ratio. The rock is believed to be definitely older than the rocks of the ring-dyke complexes.

Evidence is adduced to relate the published minimum absolute date of — 475 m.y., for the metamorphism of the Connemara Schists, to its correct position in the Lower Palaeozoic stratigraphy of Western Ireland. The metamorphism pre-dates the Didymograptus extensus zone of the Arenig in Connemara and South Mayo and an Upper Cambrian or Tremadocian age is considered likely.

The sill shows the normal type of spatial relationship found in composite intrusions of the British Tertiary, i.e. basic-acid-basic. The basic rocks are Talaidh type tholeiites while the acid rock is a rhyolite. Xenoliths appear to be concentrated in the upper and lower tholeiites. This fact has suggested to the authors of the Mull Memoir that a process of gravitational differentiation resulted in the formation of the basic and acid magmas. The evidence is inconclusive as to what process operated in magma genesis. The mineralogy of the xenoliths found in the sill is described in detail.

Attention is drawn to the widespread occurrence of perthosite bodies in the Basement Complex of southern Nyasaland, and a description of these rocks is given.

It is suggested that these rocks represent a late stage in the differentiation of basaltic or andesitic magma which produced basic intrusives and volcanics and ultrabasic complexes in the late Pre-Cambrian. These were subsequently metamorphosed at a high grade. The nepheline-syenite gneisses of Port Herald and Tambani are believed to be related to the same series.

The remarkable similarities between the late Pre-Cambrian igneous history and that of the Karroo to Chilwa Series period is commented upon, and the occurrence of similar “ring structuress” in both series is described.

Petrofabric analyses of quartz c-axes have been made at four locations round a fold in a calc-silicate rock. The movement direction during the folding is deduced from the deformation of an older lineation. Two fabrics are present: the earlier, associated with the deformed lineation, is being replaced by a fabric associated with the formation of the fold. It is shown how the symmetry of the later fabric is related not to the axis of the fold but to the direction of the movement that produced the fold; and how the quartz c-axes lie on a conical surface, giving a small circle on a stereogram plot.

A thin section of garnetiferous pelitic schist is described in which the rotation of the garnets is in either of two directions. Microfolds are seen in the slide and the garnets were rotated in opposite directions on opposite limbs of the folds. Their relation to minor structures is suggested.

The distribution of alpha radioactivity in thin sections of Shap granite is discussed and more than 95 per cent of the activity is shown to be concentrated in the accessory minerals. The results of this study are compared with those obtained for the Adamello granodiorite by other workers using similar techniques.

Four Boulder Clay-infilled channels of the upper Afon Rheidol (Cardiganshire) are described as relict river valleys of a progressive localized diversion by glacial interference.