The name Trawscoed Mudstone Formation is proposed for previously undescribed mudstones cropping-out between the Caradoc Nod Glas Formation (‘Gwern-y-Brain Group’ of Wade, 1911) and the overstepping Rhuddanian Powis Castle Conglomerate Formation some 5 km NW of Welshpool, North Wales. The mudstones have a fauna, dominated by brachiopods and trilobites, which indicates that they are contained within the Cautleyan Stage of the Ashgill Series and suggests deposition in a deep shelf environment.

The strong shock of January 14, 1919, originated in a region from which earthquakes have been absent for many years, perhaps for several centuries, and its interest is therefore increased by the fact that it was a twin-earthquake, that is, one produced by a single generative eifort in two detached foci.

Dr. F. R. Cowper Reed, in a paper entitled “Notes on the Affinities of the Genera of the Cheiruridæ”, points out that Sphærocoryphe belongs to the Cheiruridæ, while Staurocephalus, which has at first sight some superficial likeness to it, belongs probably to the Enerinuridæ.

The 170 Ma Straumsvola nepheline syenite complex in western Dronning Maud Land, Antarctica, is located on the eastern edge of the Penck-Jutul Trough, a major tectonic feature which may be a Palaeozoic-Mesozoic rift system. The 5 km diameter pluton consists entirely of nepheline syenite and can be divided into two volumetrically important units: a relatively structureless outer zone which is overlain by a layered zone. The latter exhibits continuous rhythmic alternations of layers containing different proportions of alkali feldspar to amphibole+Na-rich pyroxene+biotite+nepheline throughout its 350 m thickness. The mafic zone is a volumetrically minor unit which unconformably overlies the layered zone and consists almost entirely of mafic minerals and nepheline. The layered zone shows no systematic stratigraphic variation in major or trace composition or mineral chemistry which is interpreted as being due to a combination of migration of intercumulus liquid and action of deuteric fluids. The remarkably constant thickness of successive layers throughout the layered zone suggests that layering resulted from an internally self-regulating process(es). The layering is defined by changing proportions of alkali feldspar to mafic minerals+nepheline which is consistent with layering being caused by differences in nucleation rate during eutectic crystallization. Dykes associated with the complex show wide-ranging compositions and include both over-and undersaturated types. Low σ18O values of the nepheline syenites (mean 5.9%, n = 9) suggest that the magma from which the nepheline syenites crystallized was mantlederived. Peralkaline microgranite dykes have higher σ18O values (mean 7.3%, n = 4) and it is suggested that they are either undersaturated liquids contaminated by siliceous crust, or derived by partial melting of partly fenitized gneiss. Oxygen isotope ratios of the surrounding gneiss indicate that the intrusion of the nepheline syenite did not cause extensive circulation of meteoric or magmatic hydrothermal fluids.

I was led to make this analysis with the view of determining if possible whether the extreme hardness of the Irish Chalk were due to either a chemical, a mechanical, or a calorific alteration, from the influence of the overlying basalt. If it were owing to chemical change, we should expect to find a large per-centage of silicates and a diminution in the amount of lime; if to the influence of heat, carbonic acid would be driven off, silica would be in excess, and the presence of the insoluble bases, such as the peroxide of iron, oxide of manganese, and alumina, would become more apparent; while if a mechanical cause or pressure were the reason, no change would take place in the relative amount of the constituents. I believe the result seems to show that the induration of the Chalk must be set down chiefly to the last agency,—if to anything apart from the original formation of the rock,—and that the power of alteration exerted over it by the heat of the molten basalt has been small indeed. At the same time a certain addition has been made to it by means of water holding chemical bodies in solution.

In the Quarterly Journal of the Geological Society for 1925 (Q.J.G.S., vol. lxxxi, p. 113) I discussed the conditions of deposition of the Stockdale Shales of Valentian age. I had intended to make a detailed study of the deposits of later Silurian age, but circumstances have prevented this. I propose to offer a few notes on the subject which may be of use to other observers.

Variants of the 1959–60 eruptions of Kilauea are compared chemically with the preceding flank eruptions of 1955.

Very little is known in England of the Tertiary deposits of South Africa. Some marine beds are found, as at Bathurst, where the limestone is full of teeth of Carchadon and Lamna, and shells of Turritella Ostrea, Donax, and Lucina. The shells are preserved in the Albany Museum. I was informed that these beds are 300 to 400 feet above the sea. The teeth shown to me in their worn, polished, yellowish tone rather recalled the condition of Red Crag fossils.