In the Malin Head promontory an Older fold-system, with thrusting and folding about N.W.-trending axes, was followed by Caledonoid folding about N.E.-trending axes. The limbs of the Older folds, both major and minor, now lie in the sheet- dip of the Caledonoid folds, the dips of the Caledonoid limbs being equivalent to the plunges of the axes of the Older folds. Most of the S-planes are shared in common by the two fold-systems. The only exceptions are those that outline the closures and rising parts of the Older fold-system, and these form zones in which the S-planes strike at right angles to the Caledonoid trend. By reference to the outcrop-forms in the area described, and with the aid of plasticine models, it is demonstrated that the outcrop-forms of folded folds are readily recognjzable, and that they provide visible evidence of the approximate axial directions and relative ages of the two fold-systems. By comparative study of outcrop-forms on the models and structures seen in sections cut at right angles to each of the fold-axes, it is found that the structures differ radically from those constructed by projecting the outcrop-forms on planes normal to the axes. The “down-the-plunge” method of viewing a geological map thus provides no clue to the actual three-dimensional structure of folded folds.

The pelitic hornfelses surrounding the Carn Chuinneag–Inchbae complex have, with the other rocks in the area, been subjected to the regional metamorphism which affected the Moine Series as a whole. The minerals of the original hornfelses have reacted to form assemblages which are typical of regional rather than purely thermal metamorphism although the massive structure of the hornfelses is well preserved.

By studying the changes which took place in the hornfelses during the regional metamorphism it has been possible to deduce the most likely mineral assemblages indigenous to the original hornfelses.

The results of the chemical analyses of some of the pelitic hornfelses are presented and chemical data on some of the garnets are given. It is considered unlikely that all the garnets in the hornfelses, which are essentially almandines, formed as a result of the earlier contact metamorphism: some at least probably occur as a result of the later regional metamorphism.

The remarkable xenolithic dyke described in this paper is one of the little-known swarm of camptonite and monchiquite dykes of probable Permian age in the Northern Highlands of Scotland. It is the first intrusion containing xenoliths of ultrabasic rock to be recorded from the Glenfinnan area, although such xenoliths have been described from vents or intrusions of probable or known Permian age in Caithness in the extreme north of Scotland, and in Ayrshire and elsewhere in the south of Scotland.

Compact “streaky” rocks, from the Borrowdale Volcanic Series, English Lake District, are diagnosed in part as welded tuffs. Original glass is completely replaced, but similarity to welded tuffs elsewhere is shown by the dacitic-rhyodacitic composition, lack of bedding, and development of columnar jointing. The deposition of welded tuffs, as nuée ardentes, or incandescent tuff flows, is discussed.

The coarse porphyritic Aswan Granite used in many ancient Egyptian monuments has been held to intrude a tract of gneisses and schists. It is suggested in this paper that the granitic body was formed during a phase of granitization which followed the folding and metamorphism responsible for producing the gneisses and schists. A part of the granite retains mimetic structures inherited from the pre-existing rocks, but the southern part became mobile and developed a new structure. The intrusion of a magmatic granite in dykes and sheets followed the phase of granitization.

The uplands seem to have consisted of an interior highland north of the Thames made principally of Upper Palaeozoic rocks, and a marginal vale-and-scarp lowland of Jurassic strata on the south. This lowland bordered the Wealden morass. Much of the highland exceeded 1,000 feet. It was probably a high-level peneplain resurrected by end-Purbeck earth-movements. Two main rivers entered the swamps and account for most of the detritus. Their probable relations recall those of the contemporary rivers in Belgium.

A new genus, Peiragraptus, is proposed for graptolites having a partial diplograptid development and mainly uniserial rhabdosome. A growth series of the new species P. fallax from the Upper Ordovician of Anticosti is described.

The sequence of Miogypsina species in the type region of the Aquitanian-Burdigalian offers a good basis for correlation. Early Aquitanian corresponds to the range of M. gunteri, early Burdigalian to those of M. irregularis and M. burdigalensis, early Vindobonian to that of M. cushmani. In the western Mediterranean area application of this sequence is considered justifiable. Comparison with the similar sequence in America shows a much older occurrence of equivalent species in the western hemisphere than in Europe. A correction of the American time scale is considered premature when made on the Miogypsinidae alone.