Rhythmic layering in which the layers grade from coarse base to finer top is described in a plagioclase—pyroxene—olivine gabbro. The medium sizes of the various cumulus minerals at each level have significantly different settling velocities. Variation in the proportions of the cumulus minerals accompanies the size grading. It is shown that these characteristics can reasonably be accounted for if hydrodynamic factors exerted the main control, over-riding any chemical effects.

Three large collapse structures, two bounded by straight, vertical escarpments and curved head regions, are described from Tenerife. Similar structures appear to exist on Hierro and La Palma. Their size precludes landsliding as the dominant force in their formation, although it may have played a minor role in modifying the bounding walls. It is suggested that these structures are true volcanic collapse features developed by a ‘trap-door’ type of mechanism. The lack of classical caldera shapes appears to be a reflection of a lack of well-defined central volcanism on any of the islands, the collapses probably resulting from migration of magma away from the central rift-zones towards the flanks of the islands.

Two incomplete graptolite rhabdosomes in the Hugh Miller Collection (Royal Scottish Museum) are referable to Monograptus priodon (Bronn). The specimens were obtained from the Macduff Group, the youngest member of the Upper Dalradian succession in Banffshire (Read, 1923). This occurrence extends the upper stratigraphical range of the Dalradian Series into, at least, the Lower Silurian and possibly into the lowermost part of the Upper Silurian.

The dilational intrusion is described of some basalt dykes of Tertiary age into the Easdale Slates at Easdale, Argyllshire. The intrusive form of the dykes results from the walls of irregular fractures, guided by pre-existing planes of weakness, moving apart under magma pressure. The propagation of the fractures is discussed in relation to the external stress field controlling the intrusion of the dykes and the direction of opening of the fractures considered in relation to the magma pressure and the external stress field. The flow lineations developed at the margins of the dykes are discussed in terms of their mode of origin. Although the attitude of these lineations varies with the intrusive form of the dykes, the overall direction of flow of the magma was upwards to the north of northwest.

The deep-seated caledonoid lineaments which developed in conjunction with the L. Palaeozoic basins in Wales, S. Irish Sea and Co. Wexford, bounded elongated fault-blocks within the resistant basement and its cover; it is suggested that under compression these broke internally along contemporary, strike-slip cross-faults. In the Central Wales and N. Wales–SE Co.Wexford blocks the latter were principally E–W and N–S faults respectively. Repeated movements of diverse styles along members of all three suites have influenced sedimentalogic, volcanic, plutonic and geomorphologic events throughout the Phanerozoic; in particular, they permitted the Irish Sea Geanticline to rise above the roots of the Monian tectogene, and determined the form of the younger Irish Sea sedimentary basins.

A north-easterly palaeoslope is demonstrated for the south-eastern Scottish Borders during the Upper Devonian. Alkali basalt extrusion in the (?basal) Tournaisian was followed by initiation of the Northumberland basin as a structural feature. Basin subsidence gave rise to a south-easterly palaeoslope in the Southern Uplands and was coincident with the mid-Tournaisian marine transgression.

Pleistocene silty mudflow deposits mantle much of the valley sides and floors of the Balcombe area of the central Weald. Boulder deposits at the foot of cliffs formed of resistant bedrock sandstones are also of Pleistocene age. One well sorted sand from a gentle valley side shows surface grain textures under the scanning electron microscope indicative of wind action. The superficial deposits formed under periglacial conditions, and their distribution indicates most of the landforms are relict Pleistocene features.

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.

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.

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.