Shearing stresses acting on an incompetent layer confined between competent beds during its deformation in the development of folds, differ from those commonly accepted as the cause of a number of minor structures associated with the deformation. It is suggested that the effect of bedding drag is negligible, and that the structures described as slaty cleavage, fracture cleavage, and drag folds can be explained by the laminar flow of the incompetent material whilst accommodating itself to the interspaces determined by the more competent layers.

In both north-east Shetland and the Jotunheim area of Norway two nappes of crystalline rocks occur lying one above the other and separated in time and space by orogenic sediments. These sediments were formed in part at least by erosion of the lower, and first emplaced, of the two nappes in both areas. Later emplacement of the upper nappes caused the deformation and metamorphism of these rocks. In both Norway and Shetland large quartzite conglomerates which occur immediately beneath the upper nappes have been deformed on patterns which have been determined from a study of the pebble shapes. From these patterns in both areas it is argued that the deformation was due to flow caused by pressure differences developed in the sole of the advancing nappe and possibly to extrusion from beneath the nappe.

A petrographical description is given of some erratics from the Teifi Estuary, Cardiganshire. Rock types present include granite from Ireland; greisen and Eskdale granite from the Lake District; granophyre, picrite, diabase and gneiss from the Lleyn Peninsula; granophyre and diabase from Merionethshire.

Two adjacent areas of intrusive plutonic rocks, occurring in western Iceland are briefly discussed. These intrusions are of gabbros and granophyres, believed to be of Tertiary age, of types closely comparable to those of S.E. Iceland.

The occurrence of hypersthene in Hawaiian basalts, related broadly to the lime-silica values in the bulk analyses, is now considered and graphically expressed in terms of the quantitative proportions of the normative constituents, diopside, hypersthene, olivine, and quartz in analyses of Kilauea and Mauna Loa lavas.

Published descriptions and new field observations in Ireland and Canada confirm that strain-slip cleavage should not be classified with fracture cleavage. The term crenulation cleavage is proposed to replace the generic one of strain-slip cleavage. Crenulation cleavage differs essentially from slaty and fracture cleavage in that it only develops in laminated rocks and is consequently nearly always a secondary structure. Intense metamorphism converts crenulation cleavage into a new schistosity or cleavage with characteristics similar to slaty cleavage. Two fundamentally different types are recognized and it is suggested that crenulation cleavage is a valuable indicator of metamorphic conditions during the various phases of deformation.

Development of garnet coronas in a small meta-mafite body, forming a tilted dome within the parametamorphics, is reported and the petrography of the coronites is described. Garent coronation marks a stage in the metamorphic and textural evolution of the rocks. The origin of coronas and related features is discussed.

Gabbro is intruded near the contact of gneiss and schist groups in the Southern Province of Northern Rhodesia. The petrography of normal and altered rocks is described. The rocks may have originated as an intrusion into an original reversed drag fold which it has emphasized and distorted. Intrusion took place at a late stage of regional metamorphism and folding.

A new genus, Levifenestella, is erected, with L. maeve n.sp. from the Tournaisian of Co. Sligo, Ireland, as type species. A new species of Fenestella, F. polynodosa, from the same horizon and locality, is described. A Russian species, F. rossica Shulga-Nesterenko, is recorded from the Tournaisian of Hook Head, Co. Wexford.

Tie-line data are presented for twelve analysed igneous pyroxene pairs, from which it is demonstrated that a precise point of intersection, at or close to Wo75 En25 in the ternary diagram, does not exist. Eight tie-lines for pyroxene pairs from ultrabasic nodules in basalts are also considered. The tie-lines for metamorphic pyroxenes are compared with the igneous, and are shown to intersect over a similarly wide range, the average (Ca82 Mg18) being the same for both assemblages. It is shown that no conclusions can be drawn as to the genesis of the pyroxene assemblage, from the assumption of a characteristic tie-line intersection point. Optical determinations are considered, and shown to be of little practical value in this particular problem.

Recent collecting has revealed a typical cold mollusc fauna in the Cainscross Terrace of the Frome valley near Stroud. Cold conditions are also indicated by lithology and vertebrates. The most likely date seems to be the Irish Sea Glaciation, i.e. the main phase of the Last Glaciation.

Underground borings through the Lower and Middle Coal Measures beneath the Firth of Forth have proved sequences of rhythmically bedded volcanic detritus and a thin basalt lava. The detritus is believed to have been derived from a contemporaneous cinder cone or cones previously located by an off-shore boring. The new evidence suggests that locally there was an eastward shift of focus of eruption during Coal Measure times. The relationship of volcanism to this type of rhythmic sedimentation is discussed.