Quartz keratophyre sills interbedded with folded Devonian sediments in the Annan River Tinfield area in North Queensland have probably been intruded when the sediments were unconsolidated or only partly consolidated. The sills are compared with similar occurrences in Wales, Alaska and Australia. Some of these may have been extruded prior to burrowing into sea-bottom muds but the North Queensland examples are probably true, though very high-level, sills.

Cooling cracks form at high temperatures when a basic magma is either viscous or crystalline and hot. It is postulated that fine-grained margins form along the fractures by release of gas through the fracture network. This takes place (a) by raising the liquidus-solidus boundary due to release of volatiles, (b) by expansion of the released gas with consequent cooling. Granitic material introduced along the fractures post-dates and may recrystallize the “chilled” margins.

The paper describes reaction zones at a contact between the Older Granodiorite of Donegal and an included mass of metadolerite. The metadolerite has been converted to a biotite-rich rock and the granodiorite has been converted to a leucotrondhjemite. Chemical analyses and petrographic descriptions are given for each of the rock types.

The acute F1 folds in the Isle of Man possess Caledonoid axial planes and plunge predominantly to the north-eastern or south-western quarters at a low angle. Synchronous F1 cross-folding is locally developed and plunges steeply to the north-west or south-east. The axial planes of these acute structures have the same steep Caledonoid orientation as their orthodox associates and they share the same first axial-plane cleavage (S1). The generation of the cross-folding is related to original culminations and depressions in the Caledonoid hinges of the large-scale F1 folds. Comparison is made with early cross-folding in other parts of the Caledonides.

The petrography of the Coniston Grits is described. Volcanic and sedimentary rock fragments suggest that the sediments were derived from the Ballantrae Series of the Southern Uplands, and not the Borrowdale Volcanic Series.

There is little palaeocurrent evidence for a border land mass, but it is suggested that coarse sedimentation during the Wenlockian was restricted to the Southern Uplands by a shallowing in the border area, which was finally overcome by Ludlovian times, to allow deposition of coarser material to the south.

Methods for studying the geometry of radiating and concentric features are described and compared. The method favoured for radiating features is to assume that the straight lines, which represent the trends of the features, are of infinite length. Then, for each point on a grid, calculating the mean of the perpendicular distances from the point to each of the lines. These values are then contoured, and a centre minimizing the value of the mean estimated visually.

The methods are applied to finding the centre of the Lyttelton volcano from the external contours and finding a radiation centre for its radial dykes.

A new clay pit at Kirton in Lindsey, Lincolnshire, gives continuous exposures of 21 feet of clays and limestone nodules of the davoei Zone at the top of the Lower Lias, 18 feet of similar beds and 8 feet of Marlstone Rock Bed belonging to the Middle Lias, and 38 feet of shales and limestones of the tenuicostatum and falciferum Zones of the Upper Lias. Liparoceratid, Amaltheid, Dactylioceratid and Hildoceratid ammonites occur and allow the zones to be delimited with some accuracy.

A quarry face in County Antrim appears to show that the toe of a Tertiary lava flow has ploughed into the weathered top of the underlying lava and carried some of the weathered material forward.

Three sub-provinces are recognized in the volcanics of the southern half of Kenya as follows:—

(a) the Miocene phonolite sub-province, (b) the Mount Kenya phonolite/basanite sub-province, and (c) the Rift Valley trachyte/olivine basalt sub-province. Mela-nephelinitic lavas in the two phonolitic sub-provinces are shown to differ significantly in mineralogy, chemistry, and associated volcanics. The type of volcanic association likely to be related to carbonatite occurrences is briefly discussed.

Areas of exposed Miocene phonolite and Plio-Pleistocene trachyte are much greater than those of associated basic lavas, while intermediate types are almost lacking. Calculations show that assimilation of gneissic basement rocks by basanite (or olivine mela-nephelinite) and by olivine basalt may contribute to the development of phonolite and trachyte respectively. Available supporting evidence is discussed, both from Kenya and from similar volcanic provinces elsewhere. The additional amount of salic derivatives “which can be produced in this way is small, however, relative to the volume of basic parent involved.

Comments are given on a number of papers dealing with principles and procedure in stratigraphic classification which have appeared in British journals during 1963–65. It is emphasized that a clear distinction should be made between biostratigraphic units—bodies of rock strata characterized by certain palaeontological features and bounded by the limits of known occurrence of such features—and chronostratigraphic units—bodies of rock strata characterized by representing the rocks formed during certain time-spans of earth history and bounded above and below by isochronous surfaces. Biostratigraphic zones and the chronostratigraphic terms chronozone and stage are discussed.

A formation composed of unbedded scaly bentonitic clay containing abundant scattered exotic blocks, boulders, pebbles, and smaller fragments is described from eastern Timor. It is proposed to call this formation the Bobonaro Scaly Clay. This formation is compared closely with the Argille scagliosa of the northern Apennines. Its origin is ascribed to submarine sliding of an unstable clay mass from the area north of Timor under the influence of gravity, closely associated with the emplacement of large overthrust slices of strata that marked a climax of the mid-Tertiary orogeny in Timor. The discovery of this formation has helped to bring about a radical revision of the published views of the stratigraphy and structure of Timor.