Readers of this Magazine may remember that early last August there were descriptions in many provincial and even in some London newspapers of an extensive ‘landslip,’ which had occurred on the side of the mountain called Carnedd Dafydd, on the eastern side of the valley of Nant Ffrancon, in North Wales. The impression conveyed was perhaps somewhat exaggerated, and yet the phenomenon was on a scale quite large enough to be of geological importance.

Dr. R. H. Rastall (1932) has described the petrography of the Middle Jurassic sandstones of Eskdale and shown that they possess a remarkably restricted suite of detrital minerals, having for example no garnet or staurolite, but containing much anatase and brookite, both apparently of authigenic origin. The present writer (1934) showed that in other parts of North-East Yorkshire beds of the same age contain relatively rich heavy mineral assemblages. After a more detailed survey the writer was able to show (1939c, Text-fig. 2) that the peculiar restricted assemblage was confined to a belt or elongated oval area—which can be roughly defined as occupying the north-west and northeast quarters of Sheet 43 (Geol. Survey “one-inch” map) and the north-east quarter of Sheet 44—and that as one passed outward from this area one met with increasingly richer assemblages at all horizons in the Middle Jurassic.1 This result, as well as the results of mapping certain other characteristics of the assemblage, led the writer to suggest that this belt, which coincides closely with the Cleveland axis, is a belt along which active decomposition and alteration has occurred in these deposits after they were laid down.

Just before my departure from Tokyo to Europe, in 1908, my attention was called, by the kindness of MR. Gordon Yamakawa, to a fossil fauna from a cutting along the Yamanote line of the circum-Tokyo railway, near the Tabata station. It was seven years ago, when the railway line was still in process of construction, that Mr. Yamakawa formed a collection of fossils, consisting exclusively of molluscan remains. Of special interest is the abundant occurrence of Tellina venulosa, Schrenk, in the shell-sand, and as its presence is really of exceptional interest in the environs of Tokyo we visited the place together soon afterwards. The present brief account is contributed partly for the purpose of recording the observations of this diligent young student of fossils, whose lamentable and too early death took place last autumn, during my absence in Europe, and partly with the intention of interesting others in the further study of the Pleistocene and Pliocene geology of Tokyo, which though apparently quite simple, contains many interesting and unsettled geological questions.

This petrographic and chemical study of the Hercynian granitoids of the Central Palaeozoic Massif of Morocco covers the Zaër, Ment, Oulmès, and Moulay Bouazza plutons. These plutons are formed of biotite or two-mica, quartz-rich granodiorites and monzogranites containing reddish-brown, inclusion-rich biotites as the only essential mafic mineral; zoned plagioclase; and perthitic K-feldspar. The modal contents of micas and K-feldspar are highly variable. The granitoids are generally medium to coarse grained, massive; however foliated varieties are also commonly found, particularly at the contact of the' plutons with sedimentary rocks.

The strongly peraluminous character of the granitoids is shown by high normative corundum and high molar Al2O3/(CaO + Na2O + K2O) ratio, and is reflected by the occasional presence of aluminosilicates.

The mineralogical and chemical characteristics of the granitoids are similar to those of the S-type granites, and were inherited from the crustal source of the granitic magmas which are thought to have been generated by partial equilibrium fusion of the sandy argillaceous sediments of the Massif. The heat source for the fusion might have been provided by intrusion of mantle-derived material.

Summary. The reactions involved in oil generation are of great economic importance, but remain to be studied in detail. We have investigated the rates of three reactions which occur before and during the early stages of oil formation, and have used the predicted thermal and subsidence history of stretched basins to estimate the six reaction constants. Two of the reactions are isomerization reactions, at C-20 in a sterane and at C-22 in a hopane hydrocarbon. The third reaction converts C-ring monoaromatic to triaromatic steroid hydrocarbons. No single measure of maturity can describe the progress of these reactions. In old basins, such as the North Sea, both isomerization reactions are almost complete before appreciable aromatization has occurred, whereas in young basins, such as the Pannonian Basin in Hungary, aromatization is almost complete before appreciable isomerization of the steranes has occurred. We show that the calculated progress of these reactions agrees well with that observed in both basins if the frequency factors and activation energies are 6 x 10-3 s-1 and 91 kJ mol-1, 0.016 s-1 and 91 kJ mol-1, 1.8 x 1024 s-1 and 200 kJ mol-1 for the isomerization of steranes, of hopanes, and the aromatization of steroid hydrocarbons respectively. The rate of conversion of the R to the S form was taken to be 1.174 and 1.564 times that of the reverse reactions for sterane and hopane isomerizations respectively, and the aromatization reaction was assumed to be irreversible. All three reactions were assumed to be first order and unimolecular. The aromatization rate is consistent with laboratory observations. The rate of hopane isomerization is not, and different reaction mechanisms probably dominate at different temperatures. The same constants can be used to predict the progress of the reactions in basins which have been uplifted by inversion, such as the Lower Saxony Basin in West Germany. The geochemical observations provide estimates of the amount and time of uplift which agree with those from geological studies. Geochemical observations from the eastern part of the Paris Basin suggest that this region has also been uplifted by between 1 and 2 km.

My observations at Gavarnie commenced with the detection of the great fault of the Cirque, sketched in Bull. Soc. Géol. of 1868, and are summarized in my “Pyrenean Geology,” pp. 169, Dulau & Co., completed to 1907. The Hippurite limestone having been classed and mapped as typically metamorphosed Cambrian, on the ground that my maps and descriptions are à priori inexact, I have recently been concerned with the rectification of the simultaneously asserted Triassic age of the gypseous marls, which I have found to be Tertiary and Cretaceous, from Biarritz to Cardona. Before 1868 the Hippurites of Gavarnie and Heas were already described as anomalous by Leymerie in his Manual and papers, and by Frossard in his “Guide du Géologue.” The only specifically determined specimen mentioned by Bresson is from “near the Hourquette d'Alans,” a point touching the never-questioned Cretaceous beyond the great fault, and situated at 600 metres above the anomalous sheet in question, as it is figured on Bresson's largest sections. The only fossil of his basal Ordovician I had long previously ascertained to be in a fallen fragment from a peak to the west, outside the rocks in dispute. His ‘fundamental section’ east of Gedre is a local accident due to a fault, and his section of the Cirque is wildly in contradiction to the real stratification, as well as his section of the Spanish slope of the pass of La Canao and the Hount Sainte. All these errors are corrected on his definitive map of the French Survey, and in the report of the meeting of the Société Géologique in the Pyrenees in 1906. At that meeting the theory founded by M. Carez on the contradiction of my description of Eaux Chaudes, of Bull. Soc. Géol. of 1893, was explicitly acknowledged to be baseless and untenable by that writer himself, as well as by all present.

The author refers to his work in former years among the High-level Plateau Gravels south of the Thames, chiefly in Berks and Surrey, the results of which were given in various papers from ten to twenty years ago.6 The present note may serve as a supplement to those papers, in which the conclusion was arrived at that the gravels in question were to be regarded as distinctly of riverine origin and, upon the whole, of Pliocene age.

Portuguese Nyasaland is the name given to the most northern part of Portuguese East Africa, lying between Lake Nyasa and the Indian Ocean. It is separated from the Tanganyika territory in the north by the River Rovuma and from the Portuguese province of Mozambique in the south by the River Lurio. The territory measures about 400 miles from east to west and 200 miles from north to south and has an area of nearly 90,000 square miles. This territory is now perhaps the least known part of the once Dark Continent, but while the writer was actually engaged in the exploration of this country in 1920–1, the Naval Intelligence Division of the British Admiralty published two handbooks, the Manual of Portuguese East Africa and the Handbook of Portuguese Nyasaland, which with their extensive bibliographies contained practically everything that was known of that country up to that date (1920). These handbooks make it unnecessary in this paper to give detailed accounts of the work of previous explorers.