A primary deposit of tin and tungsten has been discovered in association with granites of the Cambrian (?) sub-volcanic igneous complex at Sabaloka, on the Nile north of Khartoum. Wolfram and cassiterite occur in a stockwork of quartz veins which also contain minor amounts of sulphide minerals. The stockwork centres around a small intrusion of primary greisen lying on the contact of a porphyritic microgranite ring-dyke but the greisen and mineralizing solutions are believed to have originated from a nearby mass of biotite-muscovite granite. The deposit has many features in common with the primary tin veins associated with the Younger Granites of northern Nigeria and other parts of northern Africa.

The presence of ignimbrite is described for the first time in Malaya. The field relations and a detailed study of the petrography support the interpretation that the 15-mile ridge outcropping in Central Kelantan, Malaya, is a thick “dyke” of ignimbrite which plugs an old feeding fissure. The Temangan Ignimbrite has a texture which is intermediate between tuff and rhyolite lava. The evidence suggests that the Temangan ignimbrite was emplaced as a tuff flow.

Photometric recording of the variation in intensity of light transmission by the analyser of a petrological microscope whilst the polarizer is rotating at a rate sufficient to eliminate the periodic output from the photocell as the polars cross and uncross, and a thin section of a crystal aggregate is slowly rotated upon its stage, is found to yield information on the direction and degree of development of any preferred optical orientation that may be present in the section. The theory of the method is considered and an equation derived for the representation of any preferred optical orientation in terms of a direct percentage of areal extent. The direction of the preferred orientation is found to be parallel to the plane of polarization of the stationary analyser when the section is rotated to a position of minimum intensity of light transmission. It is suggested that the method has potential applications in the study of any fabric which is displayed in terms of an optical orientation.

Hornblende and biotite occur very commonly in the granulite facies rocks of the areas mapped, and both appear to occur as stable phases. Thus, these hornblende- and biotite-bearing rocks find accommodation only in the hornblende-granulite subfacies. It appears that most of the rocks in the areas mapped would fall into this subfacies and the mineral assemblages of these rocks are recorded in this paper under the different chemical classes. Hornblende and biotite are very commonly present in the pelitic, quartzo-felspathic, basic and magnesian rocks; phlogopite and sphene are commonly present in the calcareous rocks. A tentative ACFK tetrahedral phase diagram has been constructed for these rocks.

The petrographical and geochemical characteristics of some basic sills and dykes from Southern Rhenish Schiefergebirge are described. The dykes are generally more altered than the sills and are classified into two types according to their relation to the lead-zinc veins found in the area. The distribution of some trace elements in the sills and dykes is given and the nature and mechanism of alteration are discussed.

Analyses, determined with the electron-probe, are given of the porphyroclast minerals of the peridotite-mylonites of St. Paul's Rocks.

A microfaunal analysis of four Mesozoic core samples from The Wash is discussed, together with an interpretation of a continuous reflection profile. The profile demonstrates an expanded Lower Cretaceous succession compared with Norfolk and Lincolnshire and the clay facies of the Valanginian Hundleby Clay is shown to extend at least to the middle of The Wash. The other core samples are proved to be of Kimmeridgian, Barremian and Upper Albian age. Two Chalk samples are also plotted.

The position of Cretaceous volcanic arcs in Japan may be indicated by outcrops of basic and ultramafic rocks.

The area to the north of Barnstaple (North Devon) was covered by a detailed gravity survey. The main gravity gradient of the Bouguer anomaly map (estimated to be 1·2 mgals per mile) confirmed the conclusions drawn by Bott et al. (1958), who attributed it to a basin of possibly Carboniferous sediments and/or Old Red Sandstone, about 4 miles thick, separated from the outcropping Devonian rocks by an assumed thrust plane.

A negative residual gravity anomaly is located over the outcrop of the Pickwell Down Sandstone. Analyses of the anomaly show that it is caused by the southwards dipping belt of sandstone and that the angle of dip of the formation decreases with depth. At a depth of about 2 miles the formation becomes nearly horizontal. Alternatively, it may terminate against an assumed thrust plane underlying the whole outcropping Devonian.

The aeromagnetic map of the area shows an elongated magnetic “high” following the outcrop of the Morte Slates. The anomaly is probably caused by near surface, highly magnetized rocks in association with the Morte Slates.

In his splendid volume Geology of the Himalayas (1964; reviewed in this Number, p. 86), Professor Augusto Gansser refers (p. 164) to the rock specimens brought back from the summit of Mount Everest by the successful Swiss climbers in 1956, and also by the American team in 1963. All the various summit specimens, Professor Gansser states, are lithologically quite identical. They consist of fine-grained, thin-bedded grey calc-schists or platy limestones. The calcites are elongated conformably with the schistosity, which seems to parallel the bedding. The detrital grains are mostly quartz, acid plagioclases and some microline, together with fine sericite lamellae, paralleling the calcites. Gansser continues: “Of special interest is the fact that both samples contain crinoidal fragments. Their large uniform calcite crystals contrast with the otherwise much finer crystalline matrix. In one elongated stem-fragment the segmentation is visible (Photo. 46), while one small plate still shows the well-preserved perforation (Photo. 47).” Moreover, he observes: “These remnants, representing the highest fossils in the world, are unfortunately not sufficiently well-preserved to allow an age-determination of the top Everest limestone. They do, however, support rather than contradict the Carboniferous (to Lower Permian) age generally assigned to the Everest limestones, on the grounds that they are overlain by the (Upper) Permian Lachi Series (Odell, 1943; Wager, 1939).”

Turbidite sandstones interbedded with argillites are cut by veins composed of quartz and ankerite derived from host sandstones during successive phases of deformation.

The existence of the oldest phase of deformation (F1) is established by the presence of its widespread vein system, which is folded by the F2 folds and cut by quartz veins of the later deformation phases.

The nature of the veining, its mode of origin and regional significance are considered.