In 1907 there appeared a memoir by F. W. Harmer, in which he suggested that a number of gorges—those at Malton and Ironbridge among them—might have originated as spillways consequent upon the blocking of the natural line of drainage by glaciers. A few years previously, Professor Kendall (1902) had interpreted some abandoned valleys in Yorkshire on the same hypothesis; a further exposition was given by Kendall and Wroot in 1924. In the present paper we propose a more fundamental origin for these channels.

In a recent memoir (Holmes and Harwood, 1937, p. 276) I had occasion to point out that “one of the most remarkable features of the igneous activity of late Cretaceous and early Tertiary times is the geochemical and petrological contrast between the kimberlite and olivine-melilitite which perforated the crust of Southern Africa and the widespread outpourings of olivine-basalt and basalt (often followed by acid rocks) in many other parts of the world”. An essentially similar contrast is found in the more recent and more localized volcanic fields of the Western Rift of Africa. The Toro-Ankole fields of multiple vents, east and south-east of Ruwenzori, are characterized throughout by undersaturated potassic types, free from felspar; whereas in the great lava fields south of Lake Kivu the dominant lavas are olivine-basalts of various types. Between these two strongly contrasted provinces, and in some respects sharing the characters of each, the Birunga field (including Bufumbira) extends across the Rift north of Lake Kivu. Although many of the lavas of this field contain abundant plagioclase and look like basalts, they have been found, with few exceptions, to be potassic types ranging from leucite-basanites to basanitoid trachybasalts. True basalts appear to be absent (Holmes and Harwood, 1937, pp. 16–18), the nearest approach to basalt—geographically as well as petrographically—being certain trachybasalts and limburgites from the south of the field, which differ from the other rocks of Birunga in having more soda than potash.

The petrography and stratigraphical setting of the Nutfield fuller's earths were recently described by E. F. Newton (I) who also made a complete study of the accessory minerals associated with the actual “fuller's earth material”, which is the main constituent of the native earths processed at Redhill, Surrey.

Kodarma is one of the most important centres for the production of muscovite mica in the mica-belt of the Hazaribagh district of Bihar. The Kodarma Reserve Forest, the petrology of which is here described, begins about 2 miles north-east of Kodarma Station and extends for a further distance of about 10 miles in that direction. It occupies an area of about 57 square miles.

The Beatrice Mine at Selibin in the Federated Malay States formed a unique type of tin deposit characterized by its richness in cassiterite and the striking paragenesis of its contained minerals. The mine, now worked out, was developed in a pipe representing a replacement of Permo-Carboniferous dolomite near the margin of the Kledang granite of the Kinta Valley and a systematic account of the geology and petrology of the deposit has been given by Mr. E. S. Willbourn, Director of the Geological Survey (F.M.S.).1 In this account the principal minerals of the pipe were shown to be tremolite, talc, mica, fluorite, and a “hydrated magnesium borate” with cassiterite and arsenopyrite as the chief ore minerals.

It has been found in many places that the mineralogy of a series of sediments varies according to the time of its deposition; and basal beds may not contain the same minerals, particularly the heavy minerals, as the upper beds of a series. This investigation was undertaken to see if there was any such variation throughout the vertical thickness of part of the Permian of North-West Australia.

The relation of the valves to the pedicle is among the fundamental characters on the basis of which the phylum Brachiopoda has been divided into five orders (see Thomson, 1927). In a previous paper (Arber, 1939), I pointed out that, on this classification, the order Protremata cannot be regarded as a homogeneous group, since in the orthids the pedicle apparently emerged through an open delthyrium, while in the strophomenid Leptaena it emerged through an entirely separate foramen situated in the ventral valve. Schuchert in 1913 (p. 383) defined the whole superfamily Strophomenacea as being characterized by a pedicle which, when present, was small, and emerged at the apex of the valve. A pedicle-foramen is, however, by no means of universal occurrence, and its existence has also been often overlooked in systematic descriptions, so that, in spite of Schuchert's definition, some doubt has nevertheless remained as to whether the form of pedicle-opening found in Leptaena and a few closely allied genera is genuinely typical of the whole of the strophomenids, thus creating a developmental distinction between that group and the orthids. I have therefore examined as many as possible of the available specimens and descriptions of the strophomenids, with the results here recorded.