The generally accepted interpretation of the structure of the Southern Uplands has been that of an anticlinorium to the north-west flanked by a synclinorium to the south-east. This structure, however, has always been illustrated as one large anticlinorium since the Hawick rocks in the core of the synclinorium have been considered to be older than the Riccarton (Wenlockian) Beds which lie to the south. In Kirkcudbrightshire, a reverse age relationship is demonstrated with the result that the beds could in fact form the southern limb of the synclinorium. When this is shown to be the case doubts are thrown on the validity of the fold and two alternative interpretations are given.

A map is presented showing a series of airborne magnetometer profiles from the north end of the South Island of New Zealand to the mouth of Waikato River. The two southern profiles are related to the exposed Upper Palaeozoic igneous rocks which are considered to extend north across Cook Strait and along the west coast of the North Island to cause the anomalies in the northern profiles. The North Island profiles are considered to reflect the Kawhia Syncline and a major anticline to the east. The eastward displacement of the magnetic low relative to the synclinal axis at the surface is considered due to the eastward dip of the axial plane of the syncline.

The area yields marbles, schists, and quartzites, probably of Hecla Hoek age, a series similar in lithology to those in the Kongsfjorden region. Their structure and metamorphic condition fit in with the general picture of Caledonian trend and of increasing orogenic activity westwards. Later faulting along the western edge of a graben has broken this ground up into independent blocks as witnessed by the disposition of the Devonian conglomerates. The youngest rocks are a southerly outlier of the plateau basalts best seen around Woodfjorden, remnants of at least two flows are preserved, both of olivine basalt rich in olivine phenocrysts and carrying inclusions of a more alkaline rock type.

The holotype of the stromatoporoid Milleporella sardoa Deninger, 1906, from the Senonian of Sardinia is redescribed and the genus Milleporella Deninger, 1906, and the family Milleporel-lidae Yabe and Sugiyama, 1935, are redefined. A new superfamily the MILLEPORELLICAE, is founded.

In the Dalradian rocks of Knapdale in south-west Argyll two groups of minor folds have been developed which share the same axial plane; their fold axes lie at right angles to each other within the common axial plane. Field evidence indicates that the two fold groups are strictly contemporaneous. One group of minor folds plunges at 40° to 020° N., and the other group plunges at 45° to 235° N., the common axial plane dipping at 70° to 305° N. Major structures parallel to both sets of minor folds are developed in the area. The fabric diagram of the fold groups shows tetragonal symmetry and this is taken to indicate that the stress field responsible for the deformation had itself tetragonal symmetry. The maximum compressive stress acted almost horizontally in a N.W.–S.E. direction while extension took place equally in all directions in a plane normal to the axis of maximum compression. The relations of contemporaneous fold structures to three basic strain patterns are briefly discussed.

Monelasmina, previously known only from the Frasnian of Europe, is described and figured from the Hay River formation (Frasnian) of the Northwest Territories, Canada. The specimens are referred to a new species, M. besti.

The general geology of the Mt. Barney Central Complex is described. This intrusive complex shows close similarity in type to the classic Tertiary ring complexes of Western Scotland and Northern Ireland. In this discussion of the complex, the similarities shown by ring dykes, cone sheets, a forcefully intruded granophyre boss, and a closed ring fault are indicated.

A sedimentary formation beneath the Bray Series is found to have an extensive outcrop in southern Co. Wicklow. Evidence is given of the Pre-Cambrian age of both series. They are exposed in a Caledonian anticlinorium, which has been cut by thrusts and high-angle faults, but they had suffered strong orogenic deformation and prolonged erosion before the unconformable deposition of Lower Palaeozoic strata.

It is suggested that the rock-suite, characteristic of the discordant bathyliths and ranging in composition from ultrabasic to ultra-acid, is formed from two magmas, a basaltic and a granodioritic, that the basic rocks are emplaced among the geosynclinal sediments before the introduction of the acid magma, and that intermediate rocks are hybrids. Further, it is suggested that hybridization takes place in two stages: first, by reaction between basic rocks and water and carbon dioxide, released from sediments as a result of deep-seated metamorphism, and rising in advance of the acid magma; and secondly, by the magma itself. The first intrusions carry shattered country rocks and are stock-like bodies, and these are followed by successive emplacements of granodiorite, the earliest of which envelop most of the stocks and are, thereby hybridized to form tonalites. Only those stocks near the margins of the later intrusions are preserved, and hence occur as satellites about the larger more acid bodies.

The order of intrusion, the grainsize of the basic hybrids, and the occurrence of hornblende is discussed and it is concluded that dioritic rocks and dioritic magmas originate at a high level in the geosynclinal pile.

Convolute bedding is described from the Lower Ludlovian in north-eastern Radnorshire in calcareous siltstones probably of the Monograptus tumescenszone. Examples of true slump-structures from the same area are given for comparison. The mode of formation of the convolute bedding is discussed and reference made to such directional information as is available from a study of the sediments.

Rafts of semipelitic rock, included within a granitic body, contain segregations of microcline, biotite, cordierite and sillimanite. These structures appear to have resulted from a process of localized metasomatic rearrangement.

In a recent account of the geology of North-east Shetland (Flinn, 1958, Quart. Jour. Geol. Soc.) two nappes of crystalline rocks lying one above the other on a base of meta-sedimentary rocks were recognised. Comparison with the Norwegian geological literature followed by field investigations in Norway has shown many similarities with the Jotunheim area of Norway. In both areas two relatively rigid nappes were thrust one after the other over the surface of the earth to their present positions. In both areas the lower of the two nappes was emplaced first and was subjected to erosion giving rise to sediments which were deposited on the nappes (Phyllite Group of Shetland and the Valdres Sparagmites of Norway). These sedimentary groups had a similar history of formation, deformation, and metamorphism, but differed somewhat in materials because the source rocks were different, although several strikingly similar rock types are present as pebbles in both areas. The remains of the first nappe and the newly deposited sediments were overrun by the second nappe in both areas. The emplacement of these nappes gave rise to considerable deformation and metamorphism in the underlying rocks. If the metamorphic rocks of Shetland are of Caledonian age, as seems likely, then it is possible that the Valdres Sparagmites and the Phyllite Group are stratigraphically equivalent: they are certainly tectonically equivalent.

A small plug-like body is made up of an intrusive breccia contained within a ring of felsite. The felsitic matrix of the breccia is of composite origin and certain textures may indicate contemporaneous breaking of crystals. Attention is drawn to the association of this diatreme with the suite of felsite, hornblende lamprophyre, and hornblendite intrusions clustered around the diapiric pluton of Ardara.

The definition of a recumbent fold as one with subhorizontal axial surface is best with difficulties when recumbent folds plunge. Recumbent folds are redefined here as folds whose axial planes give subhorizontal trace in profile plane, with the fold-axis plunging at any angle up to 80°. A neutral to slightly antiformal recumbent fold half mile across and plunging 75° is described from the Pre-Cambrian metamorphic terrain in Eastern India.

Thin sills and dykes of pitchstone and felsite and dykes of crinanite, olivine-dolerite, tholeiites of different types, quartz-dolerite, andesite, craignurite-pitchstone, felsite and porphyry are described and the importance of contact and deep-seated hybridization of two magmas of contrasting basic and acid composition in their formation established. Among the dykes, the sequence of intrusion is surmised to be as follows: basic, sub-basic, intermediate, acidic, and, again, basic.

Recent work on various Triassic, Jurassic and Cretaceous radio-larian faunas from sections in northern and north-eastern Iraq, all of known stratigraphic horizon, and from elsewhere in the Middle East, confirms the existing view that as absolute indicators of age, without associated evidence, these fossils as commonly preserved are of little use, but that in local and regional problems where they are associated with other evidence they may be of considerable stratigraphical value. The genus Meyenella is not regarded as a useful indicator for the Jurassic.

Contact metamorphism by a gabbro of an unusual slightly metamorphosed argillite with comparatively high magnesia and total iron has produced an olivine-bearing hornfels. The sediment is of such a chemical composition that an almost isochemical transformation is considered to have taken place. Only Mg shows any significant change from the sediment to the hornfels.

Chess-board albite is described and theories on its origin outlined. A new occurrence from New Brunswick, Canada, is noted and certain features of the chess-board albite, discussed which fit the theory that it results from two processes, namely metasomatism of potash feldspar to soda feldspar, and deformation. This hypothesis is applied to British localities.