One of the outstanding problems of petrogenesis at the present time is that offered by the remarkable association of sharply contrasted acid and basic rocks (e.g. granite-gabbro; granophyredolerite; pitchstone-tholeiite; and rhyolite-basalt) in igneous complexes such as those of the British Tertiary Province and those of the great lopoliths of Duluth and Sudbury in North America and the Bushveld in South Africa. The contrast was first recognized in the lavas of Iceland by Bunsen (1) and it led him to the conception that two fundamental magmas, respectively acid and basic, were concerned in the genesis of the igneous rocks of Iceland and similar provinces elsewhere. Bunsen's view, however, has had little influence in the development of petrological philosophy. The petrologists of the Geological Survey in this country, and Bowen and others in North America, have assembled a very weighty and reasonable mass of field and laboratory evidence supporting the hypothesis that the acid rocks are residual products arising from the crystallization-differentiation of basaltic magmas. In the recently published Ardnamurchan Memoir (2), for example, it is claimed that as a result of the early extraction from the Plateau Magma of olivine, pyroxenes, basic plagioclase, and iron ores, the residual magma would reach a composition “which would find expression as quartz-doleritic rocks with an acid mesostasis capable of mechanical separation and a separate existence as acid lavas or intrusions” (p. 95). Bunsen's two magmas are thus regarded as successive products from a single parent stock.

Over a period of some three years Dr. A. W. Groves has been working on the correlation of intrusions by their heavy mineral content, and the results have been published in three papers which have appeared in recent volumes of the GeologicalMagazine. The three papers read seriatim provide an interesting study of the evolution of an hypothesis which, if substantiated, would remove much, and in certain favourable cases, all of the uncertainty that usually shrouds the age of an intrusive rock-body.

As is well known, there is a great diversity of opinion with regard to the relationship of the implement-bearing beds of the Pleistocene formations and the Chalky Boulder Clay. Any facts which throw light on this vexed question might, I thought, be very acceptable and useful and I am endeavouring in this paper to bring forward what evidence I can bearing on this very difficult and perplexing subject.

I have read with very great interest Dr. Peacock's paper on the distinction between palagonite and chlorophaeite in the GeologicalMagazine, for April, 1930. On p. 170 thereof, Dr. Peacock gives a brief summary of my conclusions upon the nomenclature of chlorophaeite and palagonite as given in my paper on the same subject. Briefly, my conclusions are that as far as can be judged from existing analyses, the hydrous glassy material forming a portion of the rocks originally called palagonite has a composition that brings it within the range of composition exhibited by various specimens of chlorophaeite, and that, therefore, the term palagonite should be reserved for the impure rock, and the term chlorophaeite used for this hydrous glassy material. It was also recommended by me that the process by which in the case of the basaltic tuffs the primary glass becomes hydrated should be termed palagonitization and that the same term should be applied to the process by which the interstitial glass of basaltic lava flows is altered with production of chlorophaeite. The fact that olivine, if present, a portion of the augite, and occasionally some of the felspar, may also suffer similar alteration or be replaced, is not regarded by me as pointing to an essential difference in the two processes.

Until the last few years the Asiatic Continent has yielded remarkably few remains of Dinosaurs. The recent discoveries in Mongolia have revolutionized our knowledge of their distribution in Northern Asia, and now much new information has come to light from collections made from the Cretaceous rocks of India.

InTheGeologicalMagazine of November last, Dr. John Parkinson, referring to my paper on the “Geology of the Lower Shire—Zambezi Area ”, advanced reasons for regarding the Nachipere Series of Nyasaland as being younger than the Turoka Series of East Africa.