While studying the Cornish mineral deposits I have examined certain thin-sections cut from granite-porphyry dykes which contain numerous quartz or felspar veinlets. The structures in these veinlets and their behaviour towards the various constituents of the host rock are, I believe, sufficiently interesting to merit detailed description. The sequence of events to be deduced from these features is not commonly recognized, and the underlying principles may have a broader application to include some of the larger mineral veins in Cornwall.

Among the many faults in the Marlborough district of the South Island of New Zealand four, the Wairau, Awatere, Clarence, and Kaikoura faults, are of the first importance as boundaries between great elongated tectonic blocks that determine the high mountain ranges of this north-eastern corner of the South Island and the basins, or valleys, that guide the principal rivers draining it (Text-fig. 1). Modification of these major landscape features by erosion has proceeded very far, continuing, apparently, for a long time after the differential earth movements that initiated them had come to an end; but quite recently there has been a general renewal of movement on the ancient lines of dislocation, in some important cases with reversal of the sense of the earlier displacement.

The area to which this paper refers comprises that part of north Northamptonshire and Huntingdonshire lying to the east of the River Nene, not far from Oundle, 10 miles W.S.W. of Peterborough. It lies immediately east of the Northampton Ironstone Field, and is largely included in New Series, Sheet 171, and the adjacent parts of Sheets 157, 158, and 172 of the Geological Survey. The area was originally surveyed on the 1-inch scale by Judd (1875), and maps and memoirs published in 1872–6. Apart from the description of certain sections, notably by Beeby Thompson (1928, 1930) and Douglas and Arkell (1932), no subsequent work was done in this area until the Geological Survey commenced the primary 6-inch survey in 1939. During the progress of this work Survey Officers observed many structures which, by their relation to topography, were deduced to be of superficial origin. Hollingworth, Taylor, and Kellaway (1944, 1946) have given us a key to the interpretation of many puzzling features of structure and topography in the Jurassic scarplands, and it is their pioneer work which has made the present paper possible. In the area east of the Nene many of the types of structure described by those authors can be observed; there are, in addition, other structures which appear to be of similar origin, and which it is now desired to place on record.

War-time requirements for untwinned quartz focused attention on the laboratory production of quartz crystals. Both the Germans and ourselves devoted considerable effort to this project with the result that, by the end of the German war, both countries were in a position to begin large scale manufacture. The fact that quartz crystals can be grown from aqueous solution in a short time is of considerable significance for geologists, and the method will therefore be described in some detail.

The purpose of this note is to place on record two rare crinoids and a blastoid recently found at Coplow Knoll, Clitheroe. One of the crinoids belongs to a new species of Camerata now named Steganocrinus westheadi in honour of its finder, Mr. Stanley Westhead, of Clitheroe. The genus Steganocrinus has not hitherto been recorded from English Carboniferous rocks so that its occurrence at Coplow is noteworthy. The other crinoid, here temporarily assigned to “Pachylocrinus” conicus (Phillips), shows a considerable portion of the arms and was found by the author on a visit to Coplow last year. No other specimen of this species so complete has yet been recorded. On a later visit in the autumn of the same year a single finely preserved specimen of a blastoid was found. In its general characters this specimen does not appear to differ from Orophocrinus pentangularis (Miller), and in ordinary circumstances would call for no special comment here. Blastoids, however, are so rare at Coplow that the occurrence of this specimen, the only one ever found by the author at, or known to him from, this locality, is deemed worthy of record.

Two important papers, relating to “fronts” of metamorphism, appeared in the Bull. Soc. Géol. France during the war years, and may, in consequence, have escaped the notice of many petrologists. The contents of both papers are so closely bound up with the important subject of granitization as to render their review desirable. In the first of these papers, Perrin and Roubault (1941) describe an apparently unconformable boundary between a Triassic conglomerate and an underlying schist. The Triassic conglomerate consists of red quartzite pebbles in a sandy matrix, whilst the schist is a normal low-grade sericite-chlorite-schist of a green colour. Detailed examination of the contact, however, shows that the relations between the two rock types are by no means so straightforward as a cursory examination suggests. Although the contact between the conglomerate and the schist is generally sharp, a close scrutiny establishes the following local but remarkable apparent anomalies: (1) “Xenoliths” of the conglomerate, and isolated pebbles from it, occur within the schist. (2) “Veins” and pods of the schist occur within the Triassic conglomerate. (3) Gradational contacts are sometimes found between the schist and the Triassic sandstone, the schist facies dying out within the space of a few centimetres. On the basis of these observations Perrin and Roubault reach the inevitable conclusion that the metamorphism which gave rise to the schist actually post-dated the deposition of the conglomerate.