Although the Coalbrook-dale Coal-field has received a large share of the attention of geologists, the progress of mining operations reveals new facts from time to time, enabling us to explain away some of the difficulties which have beset earlier writers.

With the increase of population and the simultaneous pollution of rivers in this country, the question of water-supply for the purposes of human life becomes every year a more serious one. Among the many schemes which have been advanced for the supply of London with water, it has been proposed by a high authority to bring the Bagshot Sands of the London Basin under requisition. These strata, covering, as they do, a considerable area at no great distance from the metropolis, and being for the most part of a porous character, would appear to form a convenient reservoir of water, since they contain stored up within them a large portion of the rain-water which falls on portions of Berkshire, Surrey, and Hants. The water obtained from these sands, either from surfacesprings or deep wells, is free from calcareous hardness, but is highly charged with salts certain of iron, which, by oxidation on exposure to the air, yield an ochreous red precipitate, the nature of which seems generally to be but imperfectly understood. The inconvenience, however, which results, in the turbidity of the water after no great exposure to the air, and the rapid corrosion of iron pipes in which it is conveyed, are facts with which all inhabitants of the Bagshot country are only too familiar. The fact that this property of water drawn from the Bagshot Sands varies greatly according to the portions of those strata which furnish it, does not however appear to be so generally known. Recent difficulties in connection with the water-supply of our own particular district have forced the matter upon my attention; and as I have been able to arrive at some pretty definite results from the investigations in which I have been engaged for several months past, it has occurred to me that, as forming a subsidiary subject to geological science, they may be of interest to readers of the Geological Magazine.

The general object of this paper is to draw attention to the apparently close connexion between the configuration of the surface in a glaciated country like Norway, and the disposition of the principal planes of division of the rocks, whether these planes be caused by stratification, cleavage or joints.

The Gangdese magmatic belt across the southern Tibetan Plateau is juxtaposed with the Indus–Yurlung Zangbo suture zone (IYS), and many mafic microgranular enclaves (MMEs) are exposed in the belt, thus providing a window for observing deep crust–mantle processes related to the Indo-Asian collision. The Nyemo intrusion is located in the middle part of the Gangdese magmatic belt and comprises host diorites with abundant MMEs. Compared with other parts of the Gangdese magmatic belt, the host rock of the Nyemo intrusion has a mineral composition similar to that of the MME, although differences are observed in chemical contents. To explore the genetic type of the MMEs and the deep processes of the Gangdese magmatic belt, the Nyemo intrusion is selected as the research object for this paper. Here, we report zircon U–Pb geochronological and whole-rock geochemical data for host diorites and MMEs, and electron probe data for hornblendes in diorites and MMEs, and combine mineralogy, petrology, petrogeochemistry and isotope geochemistry analyses. Research has shown that diorites in the Nyemo intrusion belong to the medium-K, metaluminous series. The light rare earth elements (LREEs) and heavy rare earth elements (HREEs) are significantly fractionated, and the LREE/HREE values are 5.77–7.71. The (87Sr/86Sr)i values of the diorites range from 0.704260 to 0.704287, and the εNd(t) values are from 3.73 to 4.17. The MMEs in the Nyemo intrusion have a limited range of SiO2 contents, are calc-alkaline with metaluminous affinity, and have relatively high contents of MgO (4.34–5.00 wt %) with Mg# (Mg2+/Mg2+ + Fe2+) values of 42.36–43.53, which is close to that of evolved basic magma. The contents of REEs vary from 108.87 to 120.59 ppm and show obvious Eu anomalies. The (87Sr/86Sr)i values of the MMEs range from 0.704680 to 0.704704, and the εNd(t) values are 0.35–3.74. The crystallization temperature of the hornblende in the diorite is 820 °C, the formation depth is 5.39 km, the oxygen fugacity is ΔNNO + 0.88 and the water content is 5.95 %. The crystallization temperature of the hornblende in the MMEs is 880 °C, the formation depth is 12.18 km, the oxygen fugacity is ΔNNO + 0.38 and the water content is 8.27 %. The Nyemo MMEs are formed by magma mingling, and originate from the partial melting of the depleted mantle, while the host diorite originates from partial melting of the juvenile crust with the addition of mantle material. The formation of the Gangdese magmatic belt is related to the Indo-Asian continental collision. The break-off of the subducted Neo-Tethyan oceanic plate triggered partial melting of the asthenosphere, which resulted in accumulation of the basaltic magma and then caused the partial melting of the juvenile crust with the addition of mantle material, thus forming a variety of granitic rocks and the large Gangdese magmatic belt.

In 1928 the Trustees of the British Museum purchased for the Geological Department the skeleton of a large Ichthyosaur then being prepared in the workshop of Dr. B. Hauff in Holzmaden. During its preparation the skeleton was, with the permission of the Department, studied by Professor F. von Huene, of Tübingen, who subsequently published and adequate description and figure of it, and who reached the conclusion that it was probably a new species. Since I consider that the specimen is undoubtedly different from the others so far described as Eurhinosaurus longirostris I propose here to review briefly its main characteristics under a new specific name. As von Huene has done the most important work on the genus it is with great pleasure that I name this new species in his honour.

Goniatite faunas characteristic of the principal Namurian stages are reported in many areas of the U.S.S.R. The faunas are listed, and a brief account of some recent systematic work is given.

A narrow layer of quartzite, emplaced within epidiorite by foldthrusting, is transformed to albite-trondhjemite aplite and contiguous zones of the epidiorite are enriched in biotite. By reference to six chemical analyses it is found that, with but small additions of potash these transformations can be accounted for by the combined processes of (a) mechanical mixing of the initial quartzite and epidiorite, and (b) metamorphic inter-diffusion between this mixture and the adjoining epidiorite.

The conclusions as to the stratigraphical relations of the volcano of Rhobell Fawr, north of Dolgelley, in Wales, which were arrived at by Mr. T. H. Holland and myself, have received kindly recognition from Sir Archibald Geikie in his Presidential Address to the Geological Society of London in 1891; and we may now consider that the great ring of Arenig volcanoes, Cader Idris, the Arans, Arenig Fawr, and Moelwyn, rose upon an area already shattered by sporadic Cambrian outbursts. After again visiting Rhobell Fawr in 1892, in company with Mr. Mervyn Marshall, I feel able to give some account of the rocks that build up that volcano and its outlying fort-like masses.

Many difficulties remain to be solved and much work to be done before we rest satisfied that we can understand how flint took the peculiar shapes and position in which we find it in the Cretaceous strata.

In a previous paper the writer briefly alluded to the evidence, as known from the deep borings in East Kent, afforded by the Palæozoic and Mesozoic rocks, of the operation of a posthumous axis of unrest, probably of Charnian affinity. This conception receives further support from a study of the special characters exhibited by the Wealden of East Kent and the nature of the unconformity between these strata and the Mesozoic and Palæozoic rocks underlying them.

Widely distributed Mid-Neoproterozoic mafic rocks of the Qilian – Qaidam – East Kunlun region record the tectonic evolution of the northeastern Tibetan Plateau. This study presents whole-rock geochemistry, zircon U–Pb geochronology and Hf isotopes for the Xialanuoer gabbros of the central South Qilian Belt (SQB). Zircon laser ablation – inductively coupled plasma – mass spectrometry (LA-ICP-MS) U–Pb dating indicates that the gabbros were emplaced at ca. 738 Ma, indicating they are contemporaneous with mafic magmatism elsewhere in the northeastern Tibetan Plateau. The gabbros have low SiO2, Cr and Ni contents and Mg# values, are relatively enriched in light rare-earth elements (LREEs) and depleted in high-field-strength elements (HFSEs; e.g. Nb and Ta), have no positive Zr or Hf anomalies and have relatively high Nb/Ta but low Nb/La ratios. These data indicate that the Xialanuoer gabbros formed from calc-alkaline basaltic magmas that were originally generated by the partial melting of an enriched mantle of type-I (EMI-type) enriched region of the lithospheric mantle, underwent little to no crustal contamination prior to their emplacement, and have within-plate basalt geochemical affinities. Combining these data with the presence of widespread contemporaneous continental rift-related magmatism and sedimentation in the North Qilian, Central Qilian, South Qilian, Quanji, North Qaidam and East Kunlun regions suggests that the northeastern Tibetan Plateau underwent Mid-Neoproterozoic continental rifting, which also affected other Rodinian blocks (e.g. Tarim, South China, Australia, North America and Southern Africa).

The tectonized and metamorphosed mudrocks within the Variscan accretionary prism of the Kaczawa Mountains in SW Poland comprise sedimentary mélanges together with more coherent stratigraphic units; some represent large olistoliths deposited in a submarine trench. We infer a trend of progressive near-surface stratal disruption in mud-dominated deposits due to dewatering that forms a continuum with subduction-related tectonic structures imposed on unconsolidated sediment during deeper burial. The assemblage of characters suggests that an accretionary prism environment can influence, and leave characteristic traces of, the total burial history of a trench succession.

Much attention has been paid to composite dykes and sills during the present century, and accepted definitions of the term “composite” centre about that of Daly (1933), who has stated that composite dykes are formed by successive injection of chemically differing melts into the same fissure which widens to receive them.

THE country described in the following notes comprises the area lying between latitudes 10° N. and 11° 30′ N. and longitudes 8° 45′ E. and 10° E., and is situated in the northern portion of Bauchi province and the south-eastern portion of Kano province, Northern Nigeria.

I have from my boyhood been intimately acquainted with Snowdon and its neighbourhood, and for some years past I have been investigating the geology of the district in a systematic manner. In doing this I have paid particular attention to the lake basins, and shall in the following pages give an account of some of my investigations as far as they have gone. I say as far as they have gone, because I hope in the future to make by means of a level more accurate measurements than can be made with a pocket aneroid; and I also hope that next Summer the lakes and tarns will be sounded either by myself or by someone else; for at present we know nothing about the depth of Llyn dur Arddu, next to nothing above that of Glaslyn, and very little about Llydaw, though that little is of great importance.

Three large pipes of brecciated Torridonian sediments set in matrices of calcite and calcareous mudstone occur on the island of Raasay. Previous work has shown that these structures may be due to explosive fumarole activity during the Tertiary volcanic episode. A recent study of the Torridonian stratigraphic succession has made it possible to demonstrate that there was considerable variation in the amount of vertical collapse of the local country rock caused by the explosions. In one vent local fracturing and brecciation took place with no downward movement; in another it is possible to show that Torridonian boulders tumbled at least 350 metres down into the throat of the fumarole. The amount of vertical collapse increases from vent to vent southwards towards the Cuillins volcanic centre.

These vents are of particular interest for two reasons. Though clearly of volcanic origin they contain no volcanic material. Secondly, the carbonate matrix of analogous structures is generally believed to be due to the hydrothermal solution of underlying limestone beds. The latter are absent in these examples and the carbonate material seems to be solely of volcanic origin.