Skip and roll marks, probably the impressions of orthocones, are described from the Aberystwyth Grits (Lower Silurian, mid-Wales).

A pure anthophyllite schist occurs as a bedded deposit conformable with garnet-bearing quartz—muscovite, and quartz—chlorite—biotite schists and diopside-bearing caic-silicate rocks in the north-central part of the Nellore Schist Belt. Field and petrochemical studies show that anthophyllite schist has formed from regional metamorphism of Fe-, Mg-rich aluminous sediments aided by metamorphic differentiation due to local kinematic action under amphibolite facies conditions which is the general grade of metamorphism of the Nellore Schist Belt. A pure anthophyllite schist of sedimentary origin reported here is the first of its kind described from any terrain.

Evidence from a series of boreholes in the Shoreham area demonstrates the occurrence of an outcrop of Woolwich and Reading Beds lying beneath the drift deposits which form the floor of Shoreham Harbour. The classification of the Eocene strata, their structural relation to other deposits in the area and their conditions of deposition are examined.

The Terceira Rift is a subsidiary zone of crustal generation in the Azores to the E of the Mid-Atlantic Ridge. The geology of the island of Terceira, which straddles the rift, is thought to give an indication of the nature of the volcanic activity along this zone of crustal separation. Terceira is composed of 4 large strato-volcanoes associated with trachytic or trachybasaltic activity which have since been intruded by basaltic magmas to form monogenic cinder cones and lava flows on the flanks of these large volcanoes. There is little direct evidence of eruptions along fissures although lines of cinder cones may indicate zones of weakness in the crust.

Calcareous nannoplankton from the Globigerina silts of the western approaches of the English Channel indicate the presence of standard nannoplankton zones NN2, NN 4 and NN 5, part of which can be correlated with Neogene beds in Belgium and Northern Germany. The calcareous nannoplankton support the possibility of a connexion between the North Sea Basin and the Atlantic Ocean through the English Channel during part of the Lower Miocene.

Alternative time-scales differing by 25% have been proposed for the climatic sequence revealed by deep-sea cores. Both scales are based on radiometric data. Recent evidence which is here summarized favours the time-scale which gives the smaller values for the ages of late Pleistocene events; it supports the estimate of 40 ka rather than 50 ka for the average length of the principal climatic cycle.

In order to obtain further evidence for the tectonic environment of generation of the basaltic rocks of the Ballantrae igneous complex, specimens of pillow lavas, dolerites, glaucophane schists and amphibolites were analysed for Ti, Zr, Y and Nb. Using Ti–Zr–Y, Ti–Zr and Y/Nb diagrams, three different genetic groups have been distinguished – (i) hot-spot basalts round Downan Point, round Bennane Head as far N as Balcreuchan Port, and also within serpentinite around Lendalfoot, (ii) island arc low-potassium tholeiites between Balcreuchan Port and Gamesloup, and (iii) possible ocean floor basalts at Knockormal and Knocklaugh. The interrelationships of these groups are in doubt. The hot-spot basalts may have been erupted through oceanic crust, but they could have formed prior to, or subsequent to, the island arc activity. More likely, the hot-spot basalts formed (possibly on oceanic crust) at a considerable distance from the island arc, and the two were later brought together tectonically, probably at the subduction zone associated with the arc.

The 1973 eruption on Heimaey, Iceland, presented the opportunity to study the interaction of the principal factors that control the formation of pyroclastic fall deposits. The grain size characteristics and the dispersal of some of the scoria fall units within the Eldfell Scoria deposit are described and related to observations made on the wind speed and direction, the height of the eruption column, the ‘muzzle’ velocity and the various styles of activity during the first month of the eruption.

The Katete carbonatite is situated in an area of rifting in the NW of Rhodesia. It consists of varieties of carbonatite and of agglomerates. There is little alteration of the surrounding sandstones and there are no associated alkaline rocks. The age of the complex is mid-Cretaceous, which is about the same as the later stages of carbonatite activity in the Rufunsa Valley in Zambia.

The post-Dharwar basic dikes from Chitaldrug and Shimoga schist belts have been analysed to determine their major, minor and trace-element composition. The comparison of the results from these formations (1.4–0.95 b.y.) with those of the early Precambrian metabasalts (2.4 b.y.), which are indicative of a thin crust at the time of their extrusion shows significant differences between them. Utilizing this and results of similar studies on corresponding formations it is suggested that the present thickness of this part of the crust might have been obtained after the extrusion of the early Precambrian basalts and before the intrusion of the middle Precambrian dolerites.

Elucidation of the effects of secondary alteration on the stromatoporoid skeleton is important for the development of a sound taxonomy of the group. Four stages of progressive alteration in Palaeozoic stromatoporoids are identified and their effects summarized.

Conglomerate beds occur in an Upper Ordovician—Lower Silurian clastic sequence on the northeastern side of the Newfoundland Central Paleozoic Mobile Belt. They contain scattered pebbles and cobbles dispersed in a finely laminated sandstone and siltstone matrix. Laminations are generally 5–20 mm thick and the clasts 10–300 mm across. The laminations are locally disrupted by the clasts. These laminations have subsequently been tectonically flattened into augen around the clasts and locally disrupted by boudinage. It is concluded that these conglomerate beds represent icerafted glacio-marine deposits interbedded with turbidites which were probably deposited in a locally restricted marine environment. The deposits are interpreted on the basis of scattered fossil localities as being of Late Ordovician–Early Silurian age. They are compared with deposits of similar age elsewhere in the North Atlantic region.

None of the time scales hitherto applied to the Greenland O18 curve is considered reliable. The logarithmic time scales were based on the false assumption of constant glacial dynamics. The latest time scale, based on a supposed constant 2400- years cycle, seems to be based on another false assumption of constant cycles. A chronology based on indirect dating therefore seems superior.

The localization of graphite veins in well-defined regions within anticlinal structures of the SW sector of the island, where the rocks have been migmatitized partially by a reactivation, is very significant. The graphite mineralization seems to have taken place during the above mentioned reactivation and has followed regions of structural weakness developed during the folding of the metasedimentary rocks.

The Rayfield-Gona granite of the Jos Plateau, Nigeria, formerly regarded as an independent intrusive body, is now thought to be a roof facies of the Ngell granite. This explains several phenomena, such as the gradational contact between the two, and the distinctive mineral assemblage of the former.

Satellite imagery provides additional support for the published geology of the eastern escarpment of the Ethiopian plateau. However, of greater interest is that inspection of the imagery reveals aspects of the regional geology that have gone unnoticed. The most obvious are used to extend fault lines discussed by Kazmin & Garland (1973).

Four volcanic rocks from northern Tunisia and a syntectonic granite from northeastern Algeria were dated by the K—Ar method. The stratigraphic position of the dated rocks is determined mainly by their relationship to biostratigraphically calibrated Miocene tectonism. The K—Ar age of the granite, which is younger than latest Burdigalian and older than Early Tortonian, is 16.8 m.y. (*15.8 m.y. calculated with western decay constants). Rhyodacite at 10.9 (*10.4), rhyolite at 8.8 (*8.3), basalt at 7.3 (*6.9) and adesite at 7.0 (*6.7) m.y. are all apparently younger than Lower Tortonian.

The paper records the occurrence of ignimbrite flows at Rajula, Amreli district of Saurashtra. Three different flows of ignimbrite representing a single genetic unit have been recognized. They consist of devitrified glass shards, pumice, salic and mafic minerals and unevenly distributed basic fragments. The shards and pumice are elongated along the flow direction of the rock giving eutaxitic foliation, while the basic fragments are drawn out in the direction of flow. The low content of soda in these ignimbrites is probably due to its loss during the hydration and devitrification of the glass.