The influence of three classes of factors—geological structure, lithologic composition and spatial control over erosion—are examined by trend-surface analysis, followed by stepwise regression, in order to determine their relative importance in explaining the variation observed in the elevation of the Lower Greensand ridge of south-east England. It is concluded that structural controls are dominant, lithological controls very subordinate and the spatial control of very marginal significance.

The lithological and structural characteristics of the metamorphosed Pre-Cambrian rocks of Wales and Leinster are reviewed, and the Dutch Gin Schists are not accepted as a stratigraphical unit. The Bray Series, Cullenstown Group, Ballycogly Group and Bedded Succession of North Wales are regarded as parts of a single Monian System which accumulated in a Caledonoid trough and was involved in a late Pre-Cambrian orogeny. The latter also affected the pre-Monian basement, parts of which (possibly unrelated to one another) are seen in the gneisses of Co. Wexford (Rosslare Complex), Lleyn and Anglesey.

A dolerite intrusion on Long Island, Seychelles contains exceptionally large plagioclase (labradorite) phenocrysts essentially unzoned, set in a doleritic groundmass. Many of the mega-phenocrysts have a dark redbrown interior.

In the groundmass, zoned plagioclase is in a doleritic texture with a slightly titaniferous ferro-augite that has been almost completely replaced by an actinolite uralite.

The mega-phenocrysts are considered to have crystallized slowly at depth and concentrated locally in a chamber of basaltic magma. The portion of magma containing these plagioclase crystals was later injected to higher levels as dykes. Although emplaced in a granitic (continental) environment, the intrusion has oceanic basalt affinities, and in chemical composition resembles high alumina basalts.

Some graphite-sillimanite-schists and -gneisses, containing natrojarosite and ‘collophane’, from north-east Tanzania, are described, with an analysis, and their sedimentary origin briefly discussed.

A new interpretation of a polygonal pattern of ridges in the Marble Hill Dolomitic Limestone, at Ballymore, suggests that it was formed by a soft-bodied, worm-like organism.

Pebbles of derived Portland chert and limestone have been found in the Upper Purbeck Beds at Friar Waddon, Dorset. The Unio Bed at this locality is of unusual lithology with derived phosphatic fossils and with fish teeth. The presence of this chert in the Upper Purbeck Beds and its apparent absence in Lower Purbeck pebble beds suggests that a major phase of silicification in the Portland Stone took place at about Middle Purbeck times. Furthermore, erosion of the Portland Beds occurred in the Weymouth region, probably on the crest of the Weymouth anticline, during Upper Purbeck times.

It is suggested that the name beerbachite be reserved for fine- to medium-grained granular dyke rocks of gabbroic composition occurring in coarser-grained gabbro. It should not be used for basic granular hornfelses or xenoliths.

A metamorphosed complex of basic and acid gneisses, which occurs in north-west County Mayo, Ireland, structurally underlies younger Moinian and Dalradian type metasediments. These gneisses are compared directly with the Lewisian ‘inliers’ of the western Highlands of Scotland.