[From a collection of stones obtained from the refuse-heaps of the Kimberley Mines by Mr. Louis Atkinson, a selection was made by Prof. T. Rupert Jones and, by kind permission of Prof. Bonney, was submitted to him for examination, in packets marked I.—VIII. and X. Specimen No. IX. was sent many years ago, as a traprock with garnets from the Vaal River, by Mr. Robert Crofts Jones.—T. R. J.]

The last two numbers of the Quarterly Journal of the Geological Society contain three communications concerning rocks which are, or are thought to be, Precambrian. Two of them are in direct attack on work of mine, and the third incidentally opposes some portion of it. The materials of any reply I may have to make are, for the most part, already published in my papers, but the bearing of these facts seems to require to be pointed out.

Taking the communications in order, the first is the Anniversary Address of the President. In this he deals, so far as my work is concerned, first with Anglesey. Sir A. Geikie states that he was not prepared by previous writings for certain results he obtained. He was much astonished to find in central Anglesey so striking a counterpart to portions of the old gneiss of the north-west of Sutherland and Ross.

Few spots on the face of the globe of the extent of Iceland could be mentioned where, within the same space, an equal number of volcanos could be found. In that island, too, many volcanic eruptions have occurred, which have been, perhaps, of greater magnitude than any others recorded as having taken place anywhere else on the earth. And yet the volcanos of Iceland are but imperfectly known, and, with the exception of two or three, not one of the rest has ever been scientifically examined. Hence the fact, that geological manuals so frequently contain most erroneous statements concerning this subject. A general uncertainty prevails as to how many volcanos have actually been in a state of eruption within historical times; dates are dealt with in a confused manner; and frequently mountains come to figure as volcanos which have never shown any signs of eruptive activity.

Some large metabasaltic pillows in the uppermost part of the Palaeoarchaean Hooggenoeg Complex in the Barberton Greenstone Belt, South Africa, exhibit flow-banded margins and homogeneous cores that have a different texture and compositional variation. The margins consist of millimetre to several centimetre thick alternating bands of pale green spherulitic and darker, conspicuously variolitic varieties of non-vesicular and aphyric metabasalt, previously inferred to be due to mingling of two different types of lava. The dark cores have sharp, aphanitic contacts with the flow-banded carapaces. They lack flow banding, have coarse-grained interiors and exhibit well-preserved primary textures with pseudomorphs after prismatic pyroxene set in a groundmass containing skeletal plagioclase. The compositional range of samples from these cores is unlike that of the flow-banded metabasalt but is similar to a 19 m thick lobate metabasalt flow ~150 m stratigraphically further up, at the local top of the Hooggenoeg volcanic sequence. The pillow cores are inferred to result from the later refilling of drained hollow pillows.

Petrofabric analyses of quartz c-axes have been made at four locations round a fold in a calc-silicate rock. The movement direction during the folding is deduced from the deformation of an older lineation. Two fabrics are present: the earlier, associated with the deformed lineation, is being replaced by a fabric associated with the formation of the fold. It is shown how the symmetry of the later fabric is related not to the axis of the fold but to the direction of the movement that produced the fold; and how the quartz c-axes lie on a conical surface, giving a small circle on a stereogram plot.

In Mr. Turnbull's collection from the Sholeshook Limestone of the Sholeshook Railway Cutting there is a small but perfect ‘horse-shoe’ limb of a species of Hiarpes—a genus which has not been previously recorded from this bed. The ‘horse-shoe’ is oval and rather elongate, and narrow in proportion to its length; the arms curve inwards gently, so that their acutely pointed posterior extremities are approximate. There seems to be a marginal, single row of large pits round the outer edge of the flattened limb, but the general surface is covered with very minute punctae. The inner edge of the limb is not well preserved. The arms extend backwards to about twice the length of the head-shield.

None of the time scales hitherto applied to the Greenland O18 curve is considered reliable. The logarithmic time scales were based on the false assumption of constant glacial dynamics. The latest time scale, based on a supposed constant 2400- years cycle, seems to be based on another false assumption of constant cycles. A chronology based on indirect dating therefore seems superior.

Nearly ten years ago it was my privilege to describe the British Cretaceous forms of this Family in the Geological Magazine. The Family was seen to be capable of subdivision into at least five well-marked genera, and to these a sixth very singular and remarkable one from Aix-la-Chapelle, and also represented at Blackdown, may be added. It was then that the Family reached its zenith, and in the still later Cretaceous rocks of Europe, as a flame burns brightest near its end, so some species suddenly assumed relatively gigantic proportions, and as suddenly became extinct. A few survived in America down to that much later period, the close of the so-called Cretaceous series on that continent. Only two types lived on to the present day and only one of these has ever since Cretaceous times been represented in our area.

Since 1857, the occurrence of a gigantic species of the Selachian family Rhinobatidæ in the Lithographic Stone of Bavaria has been well known, and three fine specimens are exhibited in the Munich Museum. No figure, however, appeared until 1887, when Dr. K. A. von Zittel published the illustration he has kindly allowed to be reproduced here; and the only detailed description is that of Wagner, written about thirty years ago. Quite recently, the British Museum has acquired the counterpart of one of the fossils in the Munich collection—a female individual in a remarkable state of preservation; and this is now exhibited in the form of a slab upon the west wall of the Gallery of Fossil Fishes.

So little is known about the geology of the Amazon that it seems worth while recording a few observations made during a recent journey up that river.

Certain amygdaloid textural features have been observed in a diopside-potash felspar rock within the Lewisian of the Island of Tiree; so far as the writer is aware, such features have not previously been noted in Lewisian rocks.

Evidence as to the genesis of these textures is sparse but they appear to have attained their present nature after the principal metamorphic events which have affected the enclosing rocks.

Although unwilling to admit that in the history of our Earth special and peculiar conditions have prevailed at any period since the first advent of organic beings, yet we cannot doubt, that during particular eras, circumstances favoured the development of special groups of organisms which, in consequence, flourished in greater perfection and numbers than the rest.

The Asenvågoya Conglomerate is a thin (c. 6 m) conglomeratic body composed of mass-flow deposits and enveloped by braided-stream sandstones and conglomerates. The section studied represents the proximal part of a small-radius alluvial fan built out from the basin margin towards a flood basin. The fan was possibly generated by escarpment creation, or rejuvenation, in response to syndepositional faulting along the basin margin, and comprises sand-matrix-supported and clast-supported, sheet-like conglomerates. There is an upward change through the sequence from stream flow and surging mass-flow, through fully turbulent mass-flow and sheet flow to cohesive mass-flow deposits and then a return of braided-stream alluvium at the top of the sequence. The fan wedge demonstrates the wide range of textures possible within a ‘mass-flow” system.

A previously undescribed series of outcrops which lies nearBishop's Castle, 3.2 km S of the Longmynd-Shelve Area of Salop (Shropshire), displays a relationship between the Western Uriconian tuffs, WentnorSeries ashy turbidites (both Pre-Cambrian) and Ludlow Series siltstones. This throws further light on the structure of the Pontesford-Linley Disturbance, indicating that, in the vicinity of the outcrops, a component of its movement may have been post Ludlow in age.

LAST year Mr. J. L. Bosqui gave to the Geological Department of the British Museum part of a fossil shoal of herrings found in a marine deposit of diatoms, now being worked for commercial purposes as “celite” in Santa Barbara Co., California. The species represented has since been named Xyne grex by Professors Jordan and Gilbert, who exclude it from the genus Clupea on account of its thicker enamelled scales, enamelled opercular bones, and strong ventral scutes. The matrix, examined under the microscope, proved to consist so completely of diatoms and other siliceous organisms that it seemed desirable to submit them also to special examination. I was therefore fortunate in enlisting the services of Sir Nicholas Yermoloff, whose extended studies of such organisms make his determination and discussion of these new fossils of particular value. His notes form an interesting supplement to the following short account of the deposit, which was given by Dr. Frank M. Anderson to Professor Jordan (op. cit., p. 14):—

Having the opportunity of revisiting Munich, I have drawn up a list of the fossils which formed the basis of the “Upper Cassian Zone,” erected by me in 1893. These fossils, when I discovered them in Falzarego Valley in 1891, were then for the most part unknown. The tuffs and breccias in which they occur had been referred by Loretz to the fossiliferous Raibl horizon of the Schlern Plateau, and by Mojsisovics to the much lower horizon of Wengen strata. I found, by careful collection from strata in position, that the fauna, in addition to a fair proportion of St. Cassian types and a few Raibl types, comprised a number of types common both to Cassian and Raibl horizons and a still greater number of species which had not been found elsewhere (Q.J.G.S., 1893, pp. 31, 44, 46, 47).

In 1850, Mr. H. W. Bristow recorded, on sheet 17 of the Geological Survey Map, the existence of “conglomerate” and “recent stone” at Portland Bill.—(See Plate XIV. herewith.)

Some remarks made at a meeting of the Cornish Institute of Engineers by Dr. R. H. Rastall directed attention to the possibility of platinum being found in the Lizard. In a paper upon “Ore Deposits of Igneous Origin”, Dr. Rastall pointed out that in the Lizard the local characteristics were favourable to the presence of platinum, although no definite information of its occurrence had been reported. Much interest was aroused locally by these remarks, and the writers resolved to investigate the alluvials derived from the altered ultrabasic igneous rocks of the Lizard Group.