Nine species of ostracoda belonging to the genera Eucytherura and Cytheropteron are described from the Speeton Clay at its type locality. Eight of these species are described for the first time; the ninth species is recorded for the first time from Europe.

A short seismic refraction line has been shot just north of Cenarth in Cardiganshire across the preglacial valley of the River Teifi. The deepest point on the Ordovician basement has been found to be 30 feet below O.D.

The rocks of Castle Hill previously considered to be of Tournaisian age are now shown to be referable to he Dibunophyllum Zone. The revised age greatly simplifies the structure of the fault block.

The name Whitchurch Sands is proposed for patches of ferruginous strata scattered for 75 miles along the western edge of the Cretaceous from Stewkley, Buckinghamshire, to the Vale of Pewsey, in Wiltshire. They are interpreted as the vestiges of a marine-brackish formation of Middle Purbeck age indicating the transgressive front of an advancing sea thought to have come from the north and which left its mark farther south in the Cinder Bed of Dorset. In the past they have been regarded as Lower Greensand, Wealden, or Portland Sand. In places, e.g. Quainton, Buckinghamshire, they are overlain by undoubted Lower Greensand (Seend Ironsand) of Upper Aptian date. Both in faunal characters and in stratigraphical relations the Whitchurch Sands have much in common with the Serpulite of Hanover and the basal “Wealden” of the Bas Boulonnais.

The carbonate matrix of several pyroclastic tuff rings and cones in the Monduli-Arusha area of northern Tanganyika, is believed to be of volcanic carbonatitic origin. One of the pyroclastic tuff rings contains ejected blocks of ultrabasic composition which are minera-logically similar to the cognate xenoliths found in kimberlite pipes.

Petrographic and chemical study of biotite gneiss and charnockite and the gradational transition zone between them suggests three probable modes of origin: (i) that charnockite was regionally widespread and the biotite gneiss was derived from it by retrograde metamorphism; (ii) that the charnockite represents a conformable intrusive igneous rock which with biotite gneiss was subjected to high-grade metamorphism; (iii) that the charnockite was derived from the biotite gneiss, by the introduction of some ferrous-iron rich juvenile solution.

The latter is preferred by the author because it explains better the physical, chemical, and mineralogical characteristics of the charnockite.

Evidence is presented to show that the hornblende in the charnockite was not due to retrograde metamorphism and the conclusion is drawn that the crystallization of hypersthene is not evidence of dry conditions of metamorphism.

A method of preparing grid deviation maps for the representation of the areal composition variations in granitic bodies is described. A comparative study of this method and the trend surface method by using the data of forty-five modal analyses of Bahalda hornblende granodiorite indicates greater effectiveness of the former in several respects.

During the Laxfordian orogenic period dolerite intrusions crosscut and were chilled against vertical bands of hornblende schist that trend N.W.–S.E. Subsequent metamorphism affected both the regional hornblende schists and the dolerites, and narrow bands of hornblende schist were formed in places at the expense of doleritic chilled margins. Previous interpretations of Lewisian geochronology, tectonics and metamorphic history made on the basis of a unique pre-Laxfordian basic dyke phase, cannot be applied to the rocks south of Gairloch.

The similarity between the “whole-rock” ages of the Nchanga and Lusaka granites, 755 m.y. and 725 m.y. respectively, is misleading. The field evidence indicates that the Lusaka granite, although syntectonic, intrudes Katanga metasediments, whereas the Nchanga granite is overlain unconformably by basal Katanga conglomerate and arkose. The age of the Lusaka granite thus sets a younger limit to the age of the Katanga metasediments of the Central Province and dates the waning phases of the Lufilian orogeny. The radiometric age of the Nchanga red granite is too young for a pre-Katanga intrusive, and it is suggested that it has been modified by subsequent metasomatism.

In current direction studies, when unfolding strata to their original horizontal attitude, plunge is usually allowed for on the assumption that it was acquired by rotation about horizontal axis at right-angles to the fold axis. Errors resulting from plunge correction on this assumption, if mistaken, are examined

The late-formed joint sets in the Armorican belt of south Pembrokeshire are younger than both the folds and wrench faults of the region. On fold limbs these joint sets are oriented normal to bedding surface and symmetrically about axial-traces. Lens-belts and joint-drags parallel to the joint sets indicate a shearing pattern parallel to stratification planes. The orientations of fractures in collapsed blocks of Carboniferous Limestone, in Triassic breccias, show that the late joints were formed before the end of the Triassic. The term kathetal-joints is used for those which always remain normal to bedding surfaces.

Vol. 101, page 61, line 5, for ‘a typical’ read ‘atypical’.