Chemical and modal analyses of five Kunavaram amphibolites, together with mineralogical data on the pyroxenes and amphiboles, are given. Using petrochemical plots based on Niggli numbers, the trends of variation suggest an igneous origin.

The Obudu hornblende peridotite is described and briefly compared with similar rock types from other areas. Field evidence, petrographic studies, mineralogical and chemical composition have led to the conclusion that this rock is an independent magmatic intrusion into the hypersthene tonalite (enderbite) with which it is associated, and not a member of a differentiated series.

Four species of calcareous microfossils whose systematic position is unknown occur in very small numbers in the English Gault (Middle and Upper Albian). They are associated with much more abundant coccoliths, and are believed to be the hard parts of planktonic organisms whose possible relationships are discussed, but cannot at present be determined.

Feldspathic agglomerates and related tuff-like rocks occurring at the Bukusu carbonatite complex were long thought to have been deposited as pyroclastics during a later (Elgon) period of volcanism. Evidence is presented for a reinterpretation of these rocks as vent agglomerates and tuffisites emplaced in the central diatreme of this large, pre-Elgon, complex.

Net veined complexes and basic dykes with lobate or planar margins are commonly contained in granophyre and felsite. A study of three Tertiary centres reveals that the associations do not occur as distinct types but show gradational relations. Examples are used to illustrate a gradational morphological series. The interpretation of this series is best accounted for in terms of a basic magma invading an acid host. The factors considered capable of producing the described variations are (a) the volume of basic magma (and therefore amount of heat introduced), and (b) the degree of consolidation (ratio of crystals to melt) of the acid host.

Zircon populations in quartzo-feldspathic gneisses of the Rhiconich group of the Lewisian are indicative of a sedimentary derivation of the rocks. They are similar to the zircon population of an interbanded quartzite but differ markedly from that of an intrusive granite vein.

The rarity or absence of clastic grains in oolitic ironstones is often explained by the hypothesis of a ‘clastic trap’ in which the clastic grains are deposited before reaching the zone of iron oolith formation. If the hydrodynamic behaviour of the iron ooliths and clastic grains is considered, this is unnecessary. The two components are spatially separated due to their different densities and different behaviour, depending on whether they are in suspension or saltating, or rolling. Iron ooliths can be rolled more easily than the equivalent clastic grain size, whereas clastic grains are more easily saltated or moved in suspension than the equivalent size of iron oolith. These differences cause spatial separation of the two facies.

Geological investigations and borehole drilling on the southern margin of the Bovey basin around Mainbow ball clay mine and Ringslade open pit have shown that Devonian slate up to 30 m thick is superimposed on Tertiary sediments. A drag fold beneath the slate indicates that the slate has moved eastwards over the Tertiary material. As the slate is relatively intact and not disaggregated, hillcreep cannot be responsible for the superimposition. A large landslip involving a rotational shear cannot be responsible, as the movement plane dips into the hill over too large an area. The southern margin of the Bovey basin is therefore interpreted as a thrust fault of Tertiary age, with thrust plane dipping 10° to 30° S. It is suggested that this is a rejuvenation of the Variscan thrust recognized in the Bickington area and further west in the Holne area and that the movement on the Tertiary thrust is related to the dextral wrench movement on the Sticklepath fault.

Pipes and other solution cavities in the Upper Chalk near South Mimms contain deposits unlike those found in similar situations elsewhere in Great Britain. The cavities were formed near the sub-Palaeogene surface, and most of the deposits in them were derived from the basal Palaeogene beds (Thanetian and Sparnacian). A dark brown and very porous clay, which lines many of the pipes, is composed partly of the insoluble residue from the Chalk and partly of clay eluviated from the Palaeogene deposits. The clay was deposited from percolating water in spaces formed by dissolution of chalk at the margins of the pipes.

Classical works on Indian stratigraphy described three stratigraphic units, viz., Subathu, Dagshai and Kasauli within the Tertiary sequence of Simla Hills, India. Present work shows that the above three units represent mostly intertonguing among three distinct lithofacies, respectively termed as green, red and grey facies depending upon the dominant shale colour. Environmental significance of each facies is discussed. A road log presenting evidences of facies intertonguing on the basis of sedimentary structures is described.

The occurrence of stout and stumpy crystals of biotite elongated parallel to the schistosity and showing askew cleavage is found to be due to rotation. The relation between rotation of biotite and deformation is described. Rotated biotite contains a higher amount of FeO, TiO2 and Al2O3 in comparison to the unrotated fresh and recrystallized biotite.

Contact metamorphosed rugose corals now consist of sub-radiate to sub-parallel fibres of wollastonite. It is considered that they result from the recrystallization of corallites that were partly silicified during diagenesis.

Cross-stratified units, of the order of 1 to 12 m thick, are described from the Devonian Slieve Mish Group in the Dingle Peninsula of south-west Ireland. They are composed entirely of purplish-red or yellowish-grey and violet, medium- to fine-grained sandstone. An aeolian origin for this cross-stratification is indicated by the large size and morphology of the fore-sets, the excellent sorting of the sandstones and the associated evidence of aridity in a continental environment within a restricted basin.

A new rhombiferan cystoid, Callocystites brevis, is described from the top 45 cm of the Laurel Limestone at Sandusky, Decatur County, Indiana. The species is known from a single crushed theca and many isolated plates. C. brevis is characterized by short, unbranched ambulacra. The subfamily Callocystitinae and the genus Callocystites are redefined.

A method of estimating the rate of flow-through time of water moving in an outcrop of massive limestone is reviewed. Mean values of calcium carbonate dissolved are shown to be proportional to flow-through times. The rate of uptake is very similar in both Derbyshire and Yorkshire. The pattern demonstrated resembled the relationship between salinity and increased depth noted for deep sub-surface brines.