The Dittonian Stage in Pembrokeshire comprises the Lower Marl Group (higher beds), the Sandstone-and-Marl Group, and the Upper Marl Group (at least lower half). These formations cannot be distinguished lithologically from Dittonian strata of the Welsh Borderland 100 miles away along the depositional strike.

Cyclothems of intraformational conglomerate (scoured surface below) → sandstone → siltstone with concretions recur vertically in each area. The conglomerates in both districts consist of intraformational siltstone and concretionary debris. Flat-bedding, primary current lineation, planar cross-bedding, trough cross-bedding, and ripple-drift bedding are common to the sandstones. Suncracked siltstones abound in both Pembrokeshire and the Welsh Borderland. Slumped bedding, sandstone pipes, and animal burrows are the structures penecontemporaneous with deposition in each area.

The Dittonian strata of the Welsh Borderland are shown to be probably floodplain deposits, by reason of their close similarity to the modern sediments of the Colorado Delta floodplain and Colorado River. The occurrence of an identical facies in Pembrokeshire suggests the even wider extent of this floodplain in early Lower Old Red Sandstone times, when the sea lay far to the south of both areas.

A detailed analysis is presented of a small complex bent-fold structure that occurs in the angle of the Donegal Granite outcrop. It is the most northerly expression of the major strike swing in South-West Donegal and may be of considerable importance to the interpretation of that phenomenon. Five different lineation types are related to events leading to the severe bending of a curved tight syncline in massive quartzite. The bending occurs with surprisingly little disruption of the quartzite and must have occured under plastic conditions possibly associated with granite intrusion.

It has been suggested that the Southern Uplands fault of Scotland does not continue across central and western Ireland. Published geophysical evidence, however, strongly suggests that the fault does continue, under the Carboniferous cover, at least as far as the neighbourhood of Galway.

A specimen of shale containing an echelon of quartz-filled vertical tension fractures which merge “at depth” with a single filled fissure dipping 65 degrees confirms, in general, E. M. Anderson's interpretation of dyke echelons. Also illustrated are a change in manner of stress relief and an upward diminution of strain.

A study has been made in the laboratory of the strength of a “suite” of coal measure rocks in uniaxial and triaxial compression. From the data obtained it is demonstrated that the compressive strengths are profoundly influenced by the composition, porosity and degree of compaction of the rocks. It is indicated that these factors also influence the tensile and cohesive strengths.

Evidence is sought to prove, with reference to five examples, that major cyclic changes in Jurassic sedimentation have been controlled by eustatic rises and falls of sea level. Abrupt variations suggestive of pronounced deepening of the sea in areas of marine sedimentation in Europe are correlated with extensive marine transgressions in widely separated parts of the world. A connection is recognized between eustatic movements and evolution and migration of the invertebrate fauna, and relationships between eustatic and local, epeirogenic movements outlined.

Portable apparatus for obtaining small oriented cores for geophysical or geological purposes is described. It consists of a 34 c.c. two-stroke engine with a 12 ft. long flexible shaft to a drilling head which accommodates the drilling bit and includes a pipe through which coolant from a pressure container may pass. All this weighs under 50 lb. Imperfectly cylindrical specimens may be obtained by hand drilling, or perfect cores with the aid of either of the two rigs described. The first weighs 21 lb. and allows a number of closely spaced specimens from horizontal and inclined outcrops to be obtained. The second weighs 15 lb. and is for obtaining specimens some fixed distance apart from more difficult vertical faces. Magnetic and non-magnetic orienting devices are described. The merits of the method of sampling are briefly discussed.

An occurrence of kyanite pseudomorphing andalusite, from the Urungwe District of Southern Rhodesia, is described. The pseudomorphs, which include some of the largest of their kind so far recorded, occur in profusion in certain Pre-Cambrian pelitic schists. The original andalusite was completely converted to kyanite during regional metamorphism but the shape of the original crystals was perfectly preserved. This, together with the habit of the kyanite within the pseudomorphs, shows that the change took place under conditions of insignificant shearing stress.