Theory based on the sphere as the ideal particle, fails to account satisfactorily for the concentration of solids observed in unconsolidated natural sands, which at the same time display a substantial degree of dimensional ordering of the particles. However, when the prolate spheroid of moderate axial ratio is substituted for the sphere, a theory which is satisfied by observation becomes possible, for the reason that equal spheroids can be regularly packed in both close and open ways. A spheroid assemblage of mixed open and close packings can retain a high degree of dimensional ordering of the constituent solids, yet have a relatively low particle concentration. Observations made on sandstones carefully selected for evidence of rapid cementation seem to bear out the theory as applied to natural sands. Clusters of grains resembling the open packings of equal spheroids are found in these sandstones to be uncommon but not rare, in accordance with the theory as thus far developed.

The origin of eclogite nodules in basalt is reviewed in the light of experimental studies and the conclusion reached that many of them precipitated from basic magma as garnet-pyroxene accumulates at high pressure, although some may represent exsolved clinopyroxenite accumulates.

In the Clackmannan Syncline and the north-eastern part of the Central Coalfield the Passage Group succession between No. 2 Marine Band (?Arnsbergian, E2) and the Netherwood Coal (Kinderscoutian, R1) represents a period when meandering rivers with gently sloping floodplains replaced deltas. The succession consists of upward-fining cycles in which crossstratified sandstones with disconformable bases grade up into unstratified rooty siltstones and mudstones. The thicker sandstones probably represent meander belt deposits, the thinner sandstones the infillings of single channels and the mudstones and siltstones overbank (floodbasin) deposits. Desiccation cracks and partial oxidation phenomena indicate periods of low water table.

Xenodiscacean ammonoids from Dzhulfa in Soviet Transcaucasia, assigned to Tompophiceras, Bernhardites and Paratirolites, have been interpreted as indicating that the enclosing beds, which also contain tetracorals, productacean brachiopods and goniatites, are Lower Triassic. Critical examination of the identifications shows that these beds should be regarded as Permian, not Triassic. Tompophiceras and Bernhardites are based on Triassic type species but the specimens from Dzhulfa are not demonstrably congeneric. Interpretation of Tompophiceras as a genus with a fastigate venter is rejected. Paratirolites, previously regarded as Triassic, is evidently Permian, and is now recorded from Madagascar, this being the first record outside Transcaucasus. New evidence is presented concerning the exact age of Glyptophiceras. The Dzhulfa section has been interpreted as providing a continuous transition, in the marine facies, between beds of Permian and Triassic age. This interpretation is rejected. It remains probable that there are no sections, in any part of the world, that do so.

Examination of a contact between Late Devonian intrusive acid igneous rocks and Siluro-Devonian Mathinna hornfels. and the unconformity between these rocks and the overlying Permian beds, has revealed the relative ages of the joints developed. The steep joints of the acid igneous rocks are demonstrably of pre-Permian age although they form a pattern identical to those of the Permian beds, and each joint set is correlated with approximately parallel trending sinuous normal faults. The repeated development of the steep joints is attributed to reactivation of a fundamental mechanism. Some of the joints in the igneous rocks occur between compositional layers which have inherited their shape from the form of the joint-governed contact with the hornfels.

Commonly used variation diagrams do not convincingly distinguish strongly alkaline, alkaline and calc-alkaline rocks over the full range of silica contents, especially for more acid varieties. In particular, the Rittmann Suite Index, a, becomes invalid once SiO2 exceeds about 70%.