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.

In addition to meeting various geophysical requirements, an ultrabasic upper mantle must provide a source both for olivine nodules and for the range of “primary” basaltic types, i.e. those which are apparently uncontaminated and undifferentiated. Potassium abundances and other considerations suggest that olivine nodules represent upper mantle which has previously yielded basalt by partial fusion but is now “barren”, principally because of potassium depletion, and is unable to yield more. The possible range of potassium contents of “parent” upper mantle (still able to yield basalt) is considered and it is argued that at any concentration within this range, the potassium is not distributed between the main mantle phases as a trace component but is contained largely within a potassium-rich minor phase. It is shown that this phase is probably an amphibole and may make up between 2 and 20 wt. per cent of parent upper mantle. In addition to the isochemical phase changes to be expected with increasing depth, a transition is proposed from an upper zone of amphibole-free (barren) upper mantle to a lower zone of amphibole-bearing (parent) upper mantle. The petrogenetic and geophysical implications of such a model are discussed; in particular it provides a possible explanation for the Gutenberg low-velocity zone.

A metamorphosed basic tuff and a felsite and a felsite intrusion are described. Presence of laminar structure in the matrix of the tuff and of veinlets of tuff penetrating and acid xenolith enclosed in the tuff indicates that the fragmental assemblage moved in a manner similar in final effect to fluid injection. A felsite-tuff which grades into the felsite is thought to be the remnant of the emplaced material subsequently metasomatized in situ to produce the felsite.

Small–scale isoclinal folds in Pre–Cambrian schists and quartzites near Frenchmans Cap, Tasmania, were formed during the Pre–Cambrian Frenchman Orogeny but the large open folds were produced during the Devonian Tabberabberan Orogeny. The Mary Antiform (Devonian) at the Raglan Range can be “unrolled” to leave the foliations almost horizontal, indicating that the isoclinal folds were recumbent prior to the Palaeozoic.

Pillows are described in various stages of production from small parent lava flows. The lavas flowed into water–laden sediments down to depths at which the latter were capable of supporting the weight of lava. Because of their lack of systematic relationship to tectonic axes, certain structures observed in these sediments are interpreted as pushing folds induced by the “intrusion” of lava flows. The direction of flow of the lavas was towards the north.

Four species of Exoconularia, including E. istanbulensis, sp. nov., and one Archaeoconularia, are recorded from beds hitherto regarded as Silurian, but which are now shown to be of Middle Ordovician age. A revised stratigraphical succession is proposed.

At South Hill, 1/2 mile south-east of St. Helier, two hornblende-mica-lamprophyre dykes cut the Fort Regent granophyre. They are themselves displaced by two gently dipping shear zones and a dolerite dyke belonging to the main Jersey dyke swarm cuts the granophyre, lamprophyres, and shears, Petrographically the lamprophyres are of the spessartite-kersantite type, but the presence of euhedral brown amphibole invites comparison with the camptonites. The genesis of the lamprophyres is discussed and a significant role is assigned to volatile constituents.

Details of the Infra-Cambrian Polarisbreen Series are given, arising partly out of observations made since they were defined in outline by the authors in 1956. The Polarisbreen Series includes the distinctive Polarisbreen Tillite Formation, which correlated with the neighbouring Sveanor Formation of Nordaustlandet and with other tillites in Vestspitsbergen. They are regarded as a product of the great infra-Cambrian ice age and are correlated with world-wide tillite horizons of this age.

Previous research by the present author has established the Caledonian tectonic history of the Manx Slate Series. In particular three episodes of folding (F1, F2, F3) were recognized. The present contribution describes the sequence of metamorphic textures impressed on these metasediments during this polyphase deformation.

Two distinct episodes of metamorphism have affected the Manx Slate Series. A syn-tectonic F1 metamorphism produced a chloritezone alteration throughout the Island. A later F2 metamorphism was primarily responsible for the growth of small porphyroblasts of several minerals within the pre-existing F1 fabric. This second metamorphism is confined to the hinge of the large-scale F2 Manx synform and its effects are visible in an elongate belt following the middle of the Island. The emplacement of the porphyroblasts began during the F2 movement and continued into the static interval which preceded the third (F3) movement-phase. It was completed prior to the F3 deformation.

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.

A layer of massive and lineated hornblende-biotite-gneiss has fractured along ac-joints (perpendicular to the layering and b–lineation), at regular intervals along its lower surface in contact with a thin marble bed. The joints have been opened from below and the marble has penetrated upwards to form intrusive tongues caused by extremely plastic flow folding, as shown by the unbroken banding in the marble. The structure constitutes a variety of one-sided boudinage involving segmentation in the lowest metre or so of the hornblendic rock, while the extreme marble deformation is all accommodated in a few centimetres thickness. The structures must have developed at relatively high temperatures to allow contemporaneous segregation of quartz-feldspar pegmatite veins from the hornblendic rock, and of diopside reaction skarns at the marble junctions.

The nature of the contact between Pre–Cambrian and Palaeozoic rocks on the western flanks of the Malvern Hills is discussed. Evidence from the regional geological setting and from the contact exposed in Gullet Quarry is only consistent with a faulted junction. Interpretations by Butcher (1962), Reading and Poole (1961) cannot be supported in the field and it is proposed to revert to Groom's (1899) interpretation of the western margin of the Pre–Cambrian as the outcrop of a major fault.

Correlation of the metamorphic inlier of Co. Tyrone with the Connemara Schists, together with a reinterpretation of the"Tyrone Igneous Series" erected by J. J. Hartley, lends support to recent suggestions that the Highland Boundary Fault originated as a normal fault with downthrow to the north. The palaeogeographical implications of this are briefly discussed.

The crystallographic orientation of optic axes, the crystallographic orientation of {0112} twins and the dimensional orientation of calcite from a drag folded vein are described. The external movements that have caused the deformation of the vein are interpreted and the fabric characteristics are related to them. The calcite fabric shows a marked similarity to those which have been produced experimentally. An analysis of the quartz fabrics demonstrates that there is no significant preferred orientation of optic axes.

Progressive fitting of linear, quadratic and cubic partial trend best-fit surfaces to median grain size (X1, in mm.) and percentage of silt and clay sizes (X3) of soil samples taken from fifty locations on the Lower Greensand outcrop between Ely and Leighton Buzzard in east-central England permit up to about 40 per cent of the total sums of squares to be “explained”. The successively higher levels of mathematical generalization of regional soil size distribution indicate a decrease in soil grain size towards the south-east, a disparity between the alignment of the soil facies and the strike of the present outcrop, and the existence of zone of abnormally coarse soil facies just to the west of the line of the rivel Ivel. These three features of the regional distribution of soil sizes are interesting in that they correlate with observations which have been made on the regional distribution of bedrock size facies. Finally, a suggested correlation is made between the local zones of small median grain size and abnormally high proportions of silt andclay soil sizes—isolated as “deviations or residuals” from the fitted regional surfaces—and localities where small admixtures of glacial drift (evidenced by the presence of flints) have been observed.

An intrusion associated with the Ratagan Complex (Nicholls, 1950) outcrops in Glen Lichd, east of the main omplex. It is separated from the main complex by the Strathconon fault. The intrusion consists of red medium-grained leucocratic granodiorite and adamellite.

The material for this work came from an extensive temporary exposure in the Vale of Belvoir (South Notts) which cut across the outcrops of some 70 feet of Lower Liassic Beds. Approximately one–third of the Gryphaea shells carried developmental stages. The youngest of these consisted of larval shells closely resembling those of the modern Ostrea. During the breeding season larvae settled at least twice. The growth of spat is described. The great majority of these died in early life and relatively few grew to later stages. About 5 per cent broke loose. Many of the host shells started life attached to small shells or fragments. A study of life conditions throws light on the course of deposition in Liassic waters.

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 deformation produced by the pre-Upper Old Red Sandstone movements on the Highland Boundary Fault in a zone close to the fault was sufficiently intense to rupture the pebbles in conglomerates. The patterns of pebble fracturing are similar in type and orientation over a wide area and are comparable with the patterns obtained in the experimental deformation of brittle materials. In experimental deformation a direct relationship has been established between the fractures and the causal stresses and so from a statistical orientation of the fractures in the pebbles the directions of the principal stresses can be deduced.

The principal compression in the vicinity of the Highland Boundary Fault acted N.W.–S.E. varying in places to N.N.W.–S.S.E., normal to the trend of the fault, while the least principal stress acted parallel to the strike of the fault.

The orientation of the least principal stress parallel to the direction of the fault in the conglomerates arises through increased stress in a vertical direction due to the nature of the downbuckling of the rocks on the southern side of the fault.

The orientation of the maximum compression confirms the Highland Boundary Fault as a reverse fault of late Caledonian age rather than a Proto-Armorican wrench fault produced by N.N.E.-S.S.W. compression.

Observations have shown that some garnets in the micaceous schists of the Chor area, Himachal Pradesh, India, still retain the continuity between the Se and Si planes. The Se and Si surfaces are continuous surfaces and not merely statistical as has been assumed by some.