Whole rock rubidium-strontium age determinations on granitic bodies in S.E. Uganda give ages of 2930 m.y. for the Masaba Granite and 2430 m.y. for the Buteba Granite and granitic gneisses. The former age is considered to represent the upper age limit of the post-Nyanzian orogeny, and 2430 m.y. the upper age limit of the post-Kavirondian orogeny. A second isochron age of 2100 m.y. for the Masaba Granite may reflect a second intrusion, or remobilization of part of the original granite associated with the Buganda–Toro orogeny. Tentative correlations are suggested between these age groups and others within the Tanzanian Shield and beyond.

The genotype of Bryograptus, B. kjerulfi Lapworth, is figured and redescribed together with B. ramosus Brøgger, B. bröggeri Monsen and Pseudobryograptus cumbrensis (Elles).

By the study of dilation associated with cone-sheet emplacement and the deformation of the basal Carboniferous unconformity at the Irish Tertiary igneous centre of Carlingford, it is shown that cone-sheets are capable of producing considerable uplift. This process is also the cause of the steep-sided domes which occur at some carbonatitic centres in Kenya.

The Pebble Gravels of Hertfordshire are among the earliest Pleistocene deposits of the London Basin. They comprise at least three successive units, and according to the most recent published views the oldest of these is marine, the youngest fluviatile, the intermediate partly marine and partly fluviatile. In the absence of fossils these views have remained open to question. Electron microscope studies of the surface textures of sand-grains suggest, however, that they may well be substantially correct.

It is shown that fragments in agglomerates, which occur in chlorite schists near Tintagel, may have been both flattened and constricted. Flattening was probably associated with formation of the schistosity, and constriction with later boudinage.

Detailed studies by Flett and Green have shown the Lizard complex to be a deformed body of considerable complexity. One of the principal results of the deformation has been the recrystallization of the primary peridotite. New evidence is presented concerning the original features of this high temperature peridotite. It is concluded that in some of the primary rocks there is preserved the structure and texture of the crystallization of an interstitial pore liquid trapped within a primary framework of olivine crystals.

Gentle folding or warping, of Lower Oligocene age, pre-dating the main post-Hamstead Beds folding, is indicated where the Bembridge Marls rest unconformably on eroded Bembridge Limestone. The folding appears to have been along generally NW–SE trending axes. This trend is compatible with penecontemporaneous and even earlier folding in Southern England and adjacent parts of north-western Europe. In Southern England, the main folding may have been earlier than the Miocene age generally accepted.

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.

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.

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.

The myrmekite occurring in acid to basic charnockites of the area around Garbham and Shikaruganji, Srikakulam district, Andhra Pradesh is described. Myrmekite, whenever present, occurs only at the contact of plagioclase and potash feldspar. The textures and paragenesis of minerals suggest that potash feldspar reacted with plagioclase giving rise to myrmekite under favourable stress condition, higher stress favouring the formation of myrmekite. The difference in the stress factor or the microstrain pattern in the rock can explain the presence of myrmekite at some contacts of plagioclase–potash feldspar and absence in others.

The cordierite–sillimanite rocks first reported from Joan Lake Area, Labrador, show some unusual mineral associations and textures. Two myremkitic intergrowths, one among cordierite, potash feldspar and quartz, and the other between potash feldspar and plagioclase feldspar, are observed. The presence of microcline–microperthite and the textures described in the sequel indicate that these rocks were recrystallized at high temperature.