Bouguer gravity anomalies have been determined at seventy-nine stations on Alderney, Guernsey, and Jersey. On Alderney the anomalies are clearly dependent on the nature of the outcropping rock-types, and permit approximate values for the thickness of two outcropping rock masses to be obtained. On Guernsey the anomalies are not closely related to the surface geology, and suggest that the north-eastern coastal area is underlain by a body of dense rock, possibly of ultrabasic composition. The anomalies on Jersey indicate that the sedimentary rocks of western Jersey are underlain at no great depth by rock of density comparable to that of granite. In eastern Jersey the dominating feature of the anomalies is a pronounced “high” centred near Grande Charriére. It is shown that this feature is most reasonably considered to be the effect of a large buried gabbro intrusion.

A re-examination of Hettangian and Lower Sinemurian oysters has led to the rejection of Trueman's hypothesis on the evolution of Liostrea into Gryphaea. Gryphaea assemblages from two horizons in different parts of Britain have been subjected to bivariate and size frequency analysis. The only detectable difference is a slight size increase up the succession. No “gryphaeoid” trend is discernible in Liostrea up the Hettangian succession and the change to Gryphaea is in consequence abrupt. All the oysters of Trueman's series are referred to what are considered to be two different Linnaean species.

The various mechanisms which could cause oblique slip faulting are briefly reviewed. It is thought that such faulting may frequently arise from the existence of preferred planes of fracture within the rocks. The dynamics of this mechanism is studied in some detail and an expression is obtained for the first direction of slip within the plane under the influence of a general stress system of given orientation it is found that the initial slip may occur in any possible direction within the plane, the direction depending on the relative values of the three principle pressures. The theory suggests that when a pre-existing fault is subjected to a reorientated stress system (typical or rotated) the movement after fracture will usually be oblique. In conclusion, the general implications of the theory are discussed.

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 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.

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.

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.

Six new genera of terebratellacean brachiopods are proposed; one Triassic, one Jurassic, and four Cretaceous.

The current theories dealing with the mechanics of joint development are discussed critically. An analysis of the stress conditions which can exist in competent rocks in the crust is presented. The conclusion is reached that “Master” and “Regional” Joints can be, generically, either “tensional” or “shear” structures. They are, however, post-tectonic phenomena which develop as a result of uplift. Joints form a part of “movement pictures” because their orientation is determined by residual stresses. Reasons are given which indicate that the mechanism described is generally applicable to joint development in folded sediments, igneous rocks, and also to incompetent material.