Contrary to a previously published view, evidence is given to show that the Galway Granite is entirely later than both the quartzandesine migmatization and the potash-felspar migmatization in Connemara, and that the Oughterard Granite is probably earlier than the Galway Granite, not later. There is also strong evidence against regarding the foliated marginal granite of the north and north-east border of the Galway Granite as being different in origin from the marginal granite often found in the southern, western, and north-western borders. These results agree with the radio-chemical date of 365 m.y. determined for part of the Galway Granite.

Two types of slumps are described; small sag and drop-shaped structures in the fine sandstones which develop out of iron-ore rich laminae, and the much larger slump folds in the coarse sandstones which have wavelengths of 25 to 200 cm. and are characterized by open “synclines” linked by pointed “anticlines”. Complex structures are common. It is suggested that liquifaction of the lower parts of the slumped beds has resulted in collapse of the upper parts. Kuenen's pseudo-nodule experiments reproduce many of the observed structures.

Recent research work has revealed an area of regionally metamorphosed Pre-Cambrian schists (previously undescribed) in south-west Pembrokeshire. The name “Dutch Gin Schists” is proposed for this newly described group of rocks. The Johnston Plutonic Series (Dimetian) are seen to be intruded into these schists, and the nature of the intrusive contact is described. The structure and petrology of the schists, and the nature of diorites adjacent to the contact and that seen elsewhere in the igneous mass is compared, and a suggestion made regarding the age of the foliation. A comparison is made with the Pre-Cambrian metamorphosed rocks of Malvern, Shropshire, and Anglesey.

The paper deals with disturbances of bedding contemporaneous with deposition in Torridonian rocks of Skye and Raasay. Most of the structures described have the general form of sharp upwardly-directed peaks separated by areas of more or less undisturbed bedding; within the peaks the bedding is often contorted or destroyed. The structures are developed in sandstones and are thought to have been formed more or less in situ by the shifting and rearrangement of quicksands. An origin as a result of slumping is rejected. The appearance of the structures is thought to be connected with the environment of deposition which appears to be that of very shallow water.

Evidence is presented for the geological dating of the granitic gneiss of western Ardgour, the southernmost part of the discontinuous granitic gneiss outcrop which extends from Argyll to Inverness-shire along the Loch Quoich line between the “highly inclined” and “flat” belts of the Moines. The granitic gneiss is shown to have been formed before or early in the second of four main fold movements to which the surrounding metasediments have been subjected, and is thought to occupy the core of a complex anti-formal second major fold.

Paradoxides sp. is recorded from South America for the first time, together with an associated faunule which includes Ehmania cf. akanthophora Harrington and Kay, 1951.

Matherella (?) acuticostata sp. nov. is described from the Lower Ordovician of Trefor, near Bryngwran, in mid Anglesey.

The denudation chronology of the mountainous district of south-west Mayo and north-west Galway is closely linked with drainage superimposition from a deformed Carboniferous cover. Small outcrops of basal Viséan sandstones and conglomerates, lying on bevelled summits and wide bevelled tablelands demonstrate unequivocally that the west Connaught summit level corresponds to the base of the Carboniferous. Uplift, to produce a pre-glacial divide, is believed to have occurred in Mid-Tertiary times. Upon the uplifted, faulted, and warped Carboniferous cover a consequent drainage was developed. Superimposition on to the Caledonian basement followed and during the Pleistocene considerable glacial modifications of the pre-glacial drainage pattern took place.

Absolute age determinations by the potassium-argon method on biotite from the Musensi Hill intrusion and feldspar from a feldspathic breccia on the Mbeya Mountain Range indicate a Cretaceous age.