If historical earthquake data are to be used in studies of regional seismotectonics, it is essential to include information on likely locational uncertainty. Contributory factors include both geophysical parameters and the social environment of the event. A reconstruction of how a recent earthquake might have appeared had it occurred 300 years ago is used to demonstrate the effects of documentary survival. Limits of uncertainty are estimated for two historical earthquakes (7 October 1690 and 28 November 1880) and shown to be large. It is recommended that such events should be shown on epicentral maps as areas rather than points.

During an investigation of the ‘Yellow Sands’ and Magnesian Limestone of Durham and Northumberland, several lenticular and irregular hollows or caverns, containing ‘Yellow Sands’ and light yellow marl, were noticed in the Lower Brecciated Magnesian Limestone at Trow Rocks, about one mile south of the Tyne (see Map, Fig. 1).

From time to time I have accumulated a large number of results obtained in identifying precious stones by means of their specific gravity. From these results I have selected about 70, which will be found arranged below. The observations have been made with care, and, where no temperature is given, at 15° 5 C.; an asterisk denotes those determinations in which a very accurate assay balance by Oertling was used, and in which the specimens were immersed in alcohol, not in water. In these latter determinations any error would be confined to the third place of decimals.

The South Dehshir Ophiolite, exposed along the southwestern margin of the Central Iranian microcontinent, comprises a mantle and a crustal sequence. This massif contains serpentinized peridotites, gabbros and diabase sheeted dykes cutting across wherlite, pegmatitic gabbro and plagiogranite, and is tectonically covered by radiolarites, pelagic limestones with Late Cretaceous microfauna and lavas. Under a microscope, the gabbros exhibit mesocumulate, adcumulate and hetradcumulate textures presumably formed in open magma chambers. Hypabyssal and lava samples show tholeiitic to calc-alkaline affinities, and their compositions cluster in the fields of arc or supra-subduction zone magmatism. Binary diagrams display compositional trends of magmatic differentiation, plotting away from the mid-ocean-ridge basalt (MORB) (tholeiitic) trend and following the arc (calc-alkaline) trend. Rare Earth element (REE) and spider diagrams display various enrichments at different levels. Moderate enrichment of the large-ion lithophile elements (LILE; Rb, Ba, Th, U, La, Sr) relative to the high-field-strength elements (HFSE; Nb, Ta) and slight depletion of Ti and Zr in some patterns may be attributed to variable influences of subduction components over the depleted mantle wedge. Elemental ratios display evidence for the contribution of both fluids and melt released from the subducted slab. Few patterns display ocean-island basalt (OIB) characteristics, possibly attributed to the involvement of local mantle plumes on the partial melting of the mantle wedge. This evidence indicates that the crustal rocks of the South Dehshir Ophiolite formed in a supra-subduction zone.

In the year 1878 there was a short controversy between us respecting these beds in the pages of this Magazine. Since that date we have both enlarged our knowledge of the beds at the junction of Chalk and Greensand, and recently we have had an opportunity of meeting at Seaton in Devon, and of examining the Whitecliff and Beer Head sections together. The result of this and of friendly discussion is that we have both modified our views and have come to an agreement on the most important points about which we differedin1878. Under these circumstances we think it will save trouble and facilitate future enquiry if we jointly express our present views on the subject so far as we are in agreement.

1. Chloritic Marl.—As far as we can ascertain, this name was first applied to certain beds at the junction of the Chalk and Greensand in the Isle of Wight It was subsequently adopted by Prof. E. Forbes, for a bed which occupied a similar position in Dorset, and has since been used for any bed lying at the base of the Chalk Marl and containing fossils and green grains.

In the last volume of the Geological Magazine the question concerning the origin of the Loess has been discussed by several authors in a minute and rather excited manner. Mr. Howorth has firstly expressed his opinion on that question in the Magazine for January and February, 1882, and he there combats the theory of the formation of the Loess as set forth by Baron Kichthofen (China, Bd. I., Berlin 1877). This distinguished geographer and geologist found himself compelled to explain and defend his theory in a detailed letter to the Editor of the Geological Magazine for July last, in which he enumerates and discusses the most important arguments of his theory.

The Permian fish-fauna of England has been studied by the present writer since 1932. In 1933 Dr. H. Aldinger, then working in Professor E. A. Stensiö's laboratory in Stockholm, informed me of the constitution of a fish-fauna from East Greenland which he was studying. The resemblances to the Marl Slate fishes were remarkable, and I found it extremely difficult, and in some cases impossible, to separate certain forms found in the two areas.

The petrographical and geochemical characteristics of some basic sills and dykes from Southern Rhenish Schiefergebirge are described. The dykes are generally more altered than the sills and are classified into two types according to their relation to the lead-zinc veins found in the area. The distribution of some trace elements in the sills and dykes is given and the nature and mechanism of alteration are discussed.

Mr. Osmond Fisher, in an article in the January number of this Magazine, entitled “Convection Currents in the Earth's Interior”, speaks of my views in a way that may give a false conception of what they are on the subject of overthrusts. He appears (inadvertently, no doubt) to credit me with a disbelief in the thrust-planes occurring in the North-West Highlands. I may say at once that I am one of those who admire the way in which a band of enthusiastic geologists have worked out the structure of this most difficult tract of country, and thoroughly believe in the correctness of their conclusions. The principal object of my little paper in the November number of this Magazine (1908) was to caution geologists not to push their new-born views too far in trying to account for structural difficulties by overthrusts. It must be remembered that the Moine thrust-plane has been proved to no more than 10 miles overlap, but may, of course, be much more. Incidentally, I thought the paper likely to elicit a correspondence helping the interpretation of the phenomena of overthrusts.

Pebble-Like aggregations of calcium carbonate have been described from certain lakes in the northern United States and southern Canada under such names as squaw biscuit, marlyte, and marl balls. The most northerly of the previous records of these structures in eastern Canada, known to the writer, cites them from Emerald Lake, a small Ontario lake in latitude 47 degrees. Structures of this type are known to be products of the growth activities of certain species of the blue-green algae. Those from Canandaigua Lake, New York, have the hardness of limestone and most geologists would be likely on casual examination to class them as flat water-worn pebbles of Palaeozoic limestone. Others, such as those found in Mink Lake, near Ottawa, Canada, are much softer and less compact than limestone.

Glauconite may be described as essentially a hydrous silicate of iron and potash, but of very variable composition, and generally containing varying proportions of other bodies, such as alumina, lime, and magnesia. It is found at different horizons in the whole geological series of rocks from the Cambrian up to the most recent Tertiary layers, and, indeed, is particularly interesting in being one of the very few silicates which are in actual process of formation on the sea-bed at the present time. The physical characteristics of glauconite grains are practically the same throughout the series, the normal colour being dark green, but sometimes being yellowish, greyish, or even almost red. These variations of colour, however, mean at least the commencement of decomposition. The size of the grains is usually about one millimetre in diameter, and although much larger masses are sometimes found these are merely agglomerations of the smaller grains. Under the microscope the grains appear quite homogeneous unless some foreign body is enclosed, or, as sometimes occurs, the commencement of decomposition gives a more or less zonary appearance to them.

Since the publication in 1887 of Dr. H. B. Guppy's book (1) very little has appeared on the geology of the Solomon Islands, and Cowper Reed's book (2) of 1921 is based on Guppy for this area. During the last four years a small representative collection of rocks has been sent to the British Museum (Natural History) and examined by Mr. W. Campbell Smith, to whom the author is much indebted for their identification.

Monograptus hipposideros sp. nov., a new Lower Llandovery monograptid, is described from Coal Pit Bay, Northern Ireland. With distinct “horseshoe” curvature and simple thecal shape it is similar to, and is compared with Monograptus cyphus s.l. Lapworth, M. gregarius Lapworth and M. leei Hsü.

Since the 1980s, the Upper Jurassic lithographic limestone of the Causse Méjean (southern France) has been known by local naturalists to yield fossils. However, until the beginning of the 21st century, this plattenkalk remained largely undersampled and scientifically underestimated. Here, we present the results of two decades of prospection and sampling in the Drigas and the Nivoliers quarries. We provide the first palaeontological inventory of the fossil flora, the fauna and the ichnofauna for these localities. The fossil assemblages show the co-occurrence of marine and terrestrial organisms. Marine organisms include algae, bivalves, brachiopods, cephalopods (ammonites, belemnites and coleoids such as Trachyteuthis), echinoderms, decapod crustaceans (ghost shrimps, penaeoid shrimps and glypheoid lobsters) and fishes (including several actinopterygians and a coelacanth). Terrestrial organisms consist of plant remains (conifers, bennettitaleans, pteridosperms) and a single rhynchocephalian (Kallimodon cerinensis). Ichnofossils comprise traces of marine invertebrates (e.g. limulid trackways, ammonite touch mark) as well as coprolites and regurgitalites. Given the exquisite preservation of these fossils, the two quarries can be considered as Konservat-Lagerstätten. Both lithological features and fossil content suggest a calm, protected and shallow-marine environment such as a lagoon partially or occasionally open to the sea. Most fossils are allochthonous to parautochthonous and document diverse ecological habitats. Similarly to other famous Upper Jurassic plattenkalks of western Europe such as Solnhofen, Cerin or Canjuers, the Causse Méjean is a key landmark for our understanding of coastal/lagoonal palaeoecosystems during the Kimmeridgian–Tithonian interval.

The oceans store a substantial fraction of carbon as calcium carbonate (CaCO3) and organic carbon (Corg) and constitute a significant component of the global carbon cycle. The Corg and CaCO3 flux depends on productivity and is strongly modulated by the Asian monsoon in the tropics. Anthropogenic activities are likely to influence the monsoon and thus it is imperative to understand its implications on carbon burial in the oceans. We have reconstructed multi-decadal CaCO3 and Corg burial changes and associated processes during the last 4.9 ky, including the Meghalayan Age, from the Gulf of Mannar. The influence of monsoon on carbon burial is reconstructed from the absolute abundance of planktic foraminifera and relative abundance of Globigerina bulloides. Both Corg and CaCO3 increased throughout the Meghalayan Age, except between 3.0–3.5 ka and the last millennium. The increase in Corg burial during the Meghalayan Age was observed throughout the eastern Arabian Sea. The concomitant decrease in the Corg to nitrogen ratio suggests increased contribution of marine organic matter. Although the upwelling was intense until 1.5 ka, the lack of a definite increasing trend suggests that the persistent increase in Corg and CaCO3 during the early Meghalayan Age was mainly driven by higher productivity during the winter season coupled with better preservation in the sediments. Both the intervals (3.0–3.5 ka and the last millennium) of nearly constant carbon burial coincide with a steady sea-level. The low carbon burial during the last millennium is attributed to the weaker-upwelling-induced lower productivity.