The Island of Arran has long been celebrated among geologists for the variety and extensive development of its igneous rocks. The basaltic group is well represented in its various forms of structure and modes of occurrence; the more highly silicated series by felsites and porphyrites, forming dykes and huge amorphous or columnar masses; while the glassy varieties are illustrated by dykes and veins of pitchstone. All these rocks may be readily studied in the small area comprised within the southern half of the island, the greater part of which consists of eruptive rocks, and sandstones of the Carboniferous period. It is among these sandstones that most of the igneous rocks have been intruded. Some, however, are evidently interbedded and contemporaneous, forming great sheets of melaphyre between the Carboniferous strata.

In taking my first walk over West High Down, near Freshwater Bay, in May of last year, I found that the ground had been ploughed up by traction engines drawing heavy guns to some new forts on the Needles Point, then in course of construction. Thinking that there might be some Neolithic implements turned up, I examined the ruts, when almost the first thing I saw was a Palæolithic implement. It was ovate in form, 3¼ inches long by 2⅜ inches broad, thin, very slightly twisted, well made and symmetrical though not elaborately finished, and ochreous and almost unabraded in condition. So far as I am aware, this is the first Palæolithic implement that has been found in the district.

Note.–The Fossils about to be described were sent to England in 1873 and 1874 by Heer R. D. M. Verbeek, Director of the Geological Survey of Sumatra, and are here published by the authority and with the aid of the Dutch-Indian Government.

It has long been recognized by geologists that rock-masses which have undergone movement, and have thereby been subjected to internal stresses, exhibit, as the consequence of the action upon them of such mechanical forces, unmistakeable evidences of having been greatly modified, alike in their mineralogical and in their structural characters. That the most complete and striking examples of such changes are to be found in the rock-masses which constitute mountain-chains—rock-masses which have actually been made to “flow,” and in so doing have been subjected to shearing movements of the most intense character—was clearly pointed out by Scrope, Darwin, Sharpe, Naumann, and Dana; all of whom referred the foliated structure exhibited by such rock-masses to this cause.

The pahoehoe and pillow lavas described show many common features of morphology. A finger-like or digital flow mechanism adequately accounts for the similarities although the growth mechanism of individual lobes is by markedly different processes. An important distinction is the time taken to develop a rigid crust and its subsequent expansion by fracturing and auto intrusion. This is rapidly achieved in pillow lavas but only occurs at a late stage in the pahoehoe forms. The main factors controlling the formation of these features are the environment of eruption, the volume of erupted material and the rate of eruption.

Attention has recently been directed, particularly by the writings of Boswell (1942) and Smithson (1941, 1942), to the instability of detrital minerals. In nearly all cases where etching of mineral grains has been described the rocks have been deposited under water, as members of a continuously sedimentary series.

IN the interior of Africa, in the high region of the Portuguese colony of Angola, in localities lying at an altitude of from 3,000–4,000 feet, where the soil consists of a thick layer of sand, clearly derived from the disintegration of the underlying sandstones, one constantly meets with peculiar and interesting out-crops of iron ore in the form of brown ironstone (limonite) of a spongy texture. This brown ironstone has in some places a greyish metallic colour, in places a reddish-brown, brown, brownish-yellow, or other tint characteristic of this hydrated iron oxide, but in structure it is different from all other varieties of this kind of iron ore. The entire mass is full of irregular cavities exactly like those in an ordinary toilet sponge or in pumices, and gives the impression of a ferruginous mass inflated with gases. It also recalls the unforged iron produced in the old-fashioned methods of “burning out” metallic iron direct from the ore used by ancient metallurgists.

In the GeologicalMagazine, No. VII., Mr. C. B. Rose described the Brick-earth of the Nar Valley. To the list of Fossils which he gave at pp. 11 and 12, we can now add some minute but interesting forms, namely, four Bivalve Entomostraca and three Foraminifera. The former (all new species), determined by Mr. G. S. Brady, of Sunderland, are—

The large collection of specimens of the various species of Trinucleus from British Ordovician beds which is available for study in the Sedgwick Museum offers unsurpassed opportunities for determining the characters of the members of this interesting genus as represented in the British Isles. The following notes have been compiled from a comparative study of this material supplemented by specimens from the Jermyn Street Museum and elsewhere. The frequent addition of specimens to the collection at Cambridge since Salter and McCoy's time have allowed for a more comprehensive and complete survey to be made than was then possible, though several doubtful points still await better material before they can be cleared up.

A small micromonzonite pluton intruding Miocene extrusives of the Marysvale volcanic field of southern Utah has undergone a sequence of explosive brecciation, syenite veining, rheomorphism, calcium metasomatism and zeolitization. Skarn-like occurrences of magnetite and Al-spinel-rich feldspathoidal rocks within the outcrop are of two main types: (1) an olivine-bearing variety with occasional REE-rich minerals (zirconolite) occurs as veins and seams in desilicated latite screens and xeno-liths.; (2) an aluminous, corundum- and hibonite-bearing variety with accessory zirconolite, perovskite and armalcolite occurs mainly as fillings to the micromonzonite breccias. The chemically disparate types are interpreted as having initiated as propylitic, and argillic/alunitic, alterations of latite country rock in the early hydrothermal system of the pluton. Subsequent intrusion of the micromonzonite to higher levels has incorporated these products into the igneous complex, in which they have experienced varying degrees of nephelinization, pyrometamorphism, rheomorphism and veining.

When describing the Scottish species Poteriocrinus scotocarbonarius, doubts were expressed about the propriety of assigning it to Poteriocrinus (Wright, 1937, p. 402, 1939–40, p. 17). Before creating a new genus, however, it was considered desirable to make an examination of one of the chief figured specimens of the genotype species P. crassus Miller and to compare it with P. plicatus Austin. Up to the present it has not been possible to do this, and such an outcome seems unlikely for some time to come. In view of the great amount of work that has been done on this and allied genera in recent years, it is now reasonably certain that our Scottish forms are quite distinct from any English or American species or genera hitherto described. Hence the new genus Rhabdocrinus now proposed. The name Poteriocrinus is now discarded in favour of the original Poteriocrinites (Bassler, 1938, Moore and Laudon, 1943). The genotype species was described by Miller in 1821. The specimen illustrated by him as fig. 1 on the plate opposite p. 69 is intended to portray a complete cup apparently from the right posterior side. It has a few columnals attached. According to this figure the radials have horseshoe-shaped facets. The Austins state that this figure is a restoration, and they give an illustration of the same specimen from the same position (Austin, T. and T., 1843–7, pi. 8, fig. 3c, p. 74). Here also the radial facets are not well shown. There is accordingly still a slight doubt regarding these structures on this specimen. On Miller's plate, however, are several figures of detached radials and on the plate opposite p. 67 is a diagrammatic representation of the complete cup of P. crassus. All these figures show radials with horseshoe-shaped facets and a distinct articulating cross ridge, the facets themselves only occupying part of the upper surface of the radials. This type of structure is taken as typical of the genus Poteriocrinites. In the new genus now proposed the facets are quite different in shape and occupy nearly all the upper surfaces of the radials with no trace whatsoever of a cross ridge. The pattern of the surfaces in fact consists of a series of fine crenulations or striations which cross the facets in a transverse direction, i.e. from front to back. In addition, some facets are characterized by little pustules and prominences which are more commonly observed near the centre and towards the back or interior surface of the facets. These features constitute the chief distinguishing character of the new genus. As to the family to which Rhabdocrinus should be assigned, it clearly does not belong to the Poteriocrinitidae as now defined (Moore and Laudon, 1943, p. 54, fig. 5), and since it is impossible under prevailing conditions to trace any known family to which it can be referred, the matter is left open at present.

The westward extension of the South Wales Coalfield in Pembrokeshire is of complicated structure and the sequence is very imperfectly known. This is particularly true of the west of the county, where the coalfield has been very little worked for many years. In the eastern portion of the county, between Haverfordwest and Carmarthen Bay, the Coal Measures consist mainly of shales which have been correlated with the Lower Coal Series of the main part of the South Wales Coalfield and which are not higher than the Pulchra Zone.

The great geological interest which attaches to the fossil remains of the Musk-ox or Sheep (Ovibos moschatus, Blainv.), found in British Pleistocene deposits, and the few instances hitherto recorded of their occurrence (together with a recent discovery brought to my notice), have suggested to me the desirability of a brief enumeration of them.

Pillows are described in various stages of production from small parent lava flows. The lavas flowed into water–laden sediments down to depths at which the latter were capable of supporting the weight of lava. Because of their lack of systematic relationship to tectonic axes, certain structures observed in these sediments are interpreted as pushing folds induced by the “intrusion” of lava flows. The direction of flow of the lavas was towards the north.

Only a few years ago it was looked upon as an article of faith among geologists, that the whole globe was once in a melted incandescent state, and that the conditions of temperature now prevailing on the surface of the earth have been in process of time produced by the slow gradual cooling of the once fused and glowing mass. It then appeared so natural that, in consequence of the earth’s internal heat, a tropical climate should extend from pole to pole, that no special weight was attached to the evidences of this fact which geology was at that time able to produce. The Dane Giesecke’s and the English Scoresby’s specimens of fossil plants from the east and west coasts of Greenland, evidencing a warm climate there, attracted so little attention, that neither they, nor the fossil remains of Saurians found by the famous Arctic traveller Sir Edward Belcher in the American Polar Archipelago, could be found in the museums to which they had been confided.

As a worker among the Lower Palæozoic rocks of Wales I have for some years devoted a good deal of time to the study of Tremadoc and Arenig rocks, and in common with others have therefore often wished to check the results attained in that district of great thicknesses and tectonic complication by reference to the thinner and more fossiliferous series of the undisturbed areas of Northern Europe. When, therefore, the Senate of the University of Cambridge granted me the Worts Fund for travelling scholars, and instructed me to study the interrelationships of the Tremadoc and Arenig Series in Scandinavia, I at once took advantage of the opportunity, and spent the months of May, June, and July in hammering over those rocks in the field.

The ancient Brachiopodous genus Siphonotreta is well known by its species occurring in the Ordovician and Silurian strataof Russia and Great Britain, and its peculiar pedicle opening hasbeen the subject of remark. The author is not aware that this genus has hitherto been reported from any Cambrian terrain, and, therefore, the greatest interest will attach to a form recently found in the lower beds of the St. John Group, which is nearer to Siphonotreta than to any other known genus.

The Chahmileh Pb–Zn deposit, located northwest of the Central Iran Zone, is a sediment-hosted Pb–Zn deposit in the ‘Yazd-Anarak Metallogenic Belt’. It is hosted in Middle Triassic carbonate rocks and is mainly controlled by NW-trending faults. The main ore minerals are galena and sphalerite with minor chalcopyrite, pyrite, and quartz, dolomite, along with minor calcite and baryte as gangue minerals. Cerussite, hemimorphite, wulfenite, mimetite, smithsonite, malachite and iron oxy-hydroxides are the main non-sulphide ore minerals. The main styles of mineralization are vein-veinlet, breccia, disseminated and replacement in association with silicification and dolomitization. Microthermometry of fluid inclusions in dolomite and quartz indicates that the ore precipitated from a warm to hot basin-derived saline fluid. Dolomite samples have δ13CVPDB and δ18OVSMOW values of −0.99 to +1.99‰ and +20.74 to +25.48‰, respectively, and are plotted in the marine carbonate rocks field. These isotopic values suggest that CO2 in the hydrothermal fluids mainly originated from marine carbonate rock. The δ34S values range from +6.3 to +8.2‰ for galena, +5.9 to +6.2‰ for sphalerite, +1.4 to +3.4‰ for chalcopyrite and +15.0 to +17.4‰ for bayite are compatible with a predominant thermochemical sulphate reduction process, and with sulphur sourced from Triassic seawater. Galena samples have a homogeneous Pb isotopic composition that is indicative of a continental crustal reservoir as the main source of lead and probably for the other ore metals. Based on geology, mineralogy, texture and fluid characteristics, the Chahmileh deposit is classified as a carbonate-hosted Mississippi Valley-type deposit.