Well-preserved examples of spilites show marked affinities with certain tholeiites in texture, chemistry, differentiation trend, and in some aspects of their mineralogy. The presence in them of albite and apparently primary chlorite, in association with unaltered augite, is ascribed to the influence of water as a component of the magma, and the high content of alkali in the basic members to retention of volatile oxides present in tholeiitic magma. Evidence is lacking of large-scale metasomatism by external agencies and the postulate of a special primary magma seems unwarranted. A series may be traced, in rocks of different environments, from “dry tholeiite” to “wet tholeiite” to spilite.

Four new rock analyses and one of chlorite are given.

Some essential features of the general tectonic description of a region are outlined under the above heads. Tectonic style is the product of facies and orientation in their distinctive sequence, and is assumed to be independent of date. A type of tectonic sequence is outlined from Ny Friesland, Spitsbergen, with a distinct late stage elongation along the fold axes.

Almandine-rich garnets occur as euhedral crystals in extrusive and intrusive rocks which range in composition from 59 per cent, to 70 per cent. SiO2. Eight complete garnet analyses (major and trace elements) indicate a small variation in composition which, together with corresponding variation of physical properties, appear to correlate with the mineralogical composition of the containing rock. Field, microscopic and chemical evidence suggests, on balance, that the garnets are pyrogenetic. Magmatic conditions suitable for the crystallisation of almandine-rich garnet are discussed.

The pre-Cambrian rocks of the Southern portion of Southampton Island are composed of acid gneisses of very variable character containing a few, commonly zoned, xenoliths. The petrography of both is described; eight new analyses are given, and the probable origin of several of these xenoliths is suggested.

A petrochemical study of the Pen-y-Gader dolerite has been made. The intrusion produced a mild thermal metamorphism in the country sediments and then a late-stage metasomatism affecting the dolerite as well as producing spilosites and adinoles in the country rocks. The main metasomatism involved the introduction of sodium with small amounts of boron and fluorine into the sediments. The range of activity beneath the intrusion was governed by the porosity of the sediments affected, coarsegrained bands being followed for greater distances. The chemical and mineralogical variations within the dolerite have also been compared with those observed in certain of its ophitic neighbours.

The occurrence of a goniatite horizon in the Yoredale Series exposed on Ingleborough can now be recorded. The goniatite, Neoglyphioceras cf. spirale (Phillips) was found in shales underlying a limestone which may probably be the Five Yard.

Elhuyar, born in Spain in 1755, received a thorough training in mining geology at several of the leading European mining schools. He was appointed to an important post in New Spain (Mexico), where he arrived in 1788. There he devoted himself to reorganizing the administration of the mining industry and then to founding a School of Mines in Mexico City. This was opened in 1792, and in 1811 moved into the magnificent new building known as El Palacio de Minería, which now houses the Engineering School of the University. When an independent government was set up in Mexico in 1821, Elhuyar returned to Spain, where he continued to work for the government as a mining consultant. He prepared a report on the Rio Tinto mines and was responsible for the planning of the School of Mining Engineering in Madrid.