THE history of the British Isles in the Pliocene has an important bearing on their glacial geology and on the origin of their existing geographical features. Physiographic evidence indicates that the Lower Pliocene was in Britain an epoch of depression, during which the sea covered parts of South-Eastern England, whereas the Middle and Upper Pliocene were marked by an uplift which excluded the sea from the British Isles, except in East Anglia and Western Cornwall. It is generally agreed that this uplift raised the low-lying plains that had been formed during the Lower Pliocene into plateaus from 500 to 1,400 feet above sea-level. The uplift lasted through a long period of time; and such a slowly rising land would naturally be greatly denuded by rivers. Plateaus and platforms due to the Pliocene uplift have been described by Dr. Mort for Arran and by Professor W. M. Davis for Snowdon; yet in their discussion of the present topography of those districts they attribute a very slight influence to stream erosion during the long pre-Glacial elevation.

Mr. G. W. Lamplugh and the late Mr. J. F. Walker published a paper in 1903 on a fossiliferous bed at the top of the Lower Greensand, exposed in sand-pits at Shenley Hill, near Leighton Buzzard. The bed in question presented points of considerable lithological interest and was remarkable for its rich brachiopodfauna. Its position above the “silver-sands” of the Lower Greensand and below a capping of dark “shaly clay”, ascribed by those observers to the Lower Gault, led to the conclusion that it belonged to the top part of the Lower Greensand. The discovery of its fossils was considered to throw welcome light on the faunal characters of the latest Lower Cretaceous rocks in England, represented in more southern counties by relatively unfossiliferous sands.

AT the present time most mining geologists appear to be in general agreement on the principle that primary ore-deposits are derived from igneous magmas. Furthermore, it is now almost universally recognized that the segregation and concentration of the metals and their compounds into payable ore-deposits is but part of a larger and more fundamental problem, namely, the differentiation of the igneous rocks, a problem which has exercised the ingenuity of petrologists for many years past and is still by no means solved. Unfortunately most of the speculations and theories put forward in explanation of these phenomena are in the main founded on facts and inferences derived from the study of the silicates; comparatively few petrologists have taken into account the behaviour of the oxidic and sulphidic compounds of the useful metals, which are commonly regarded in the light of rare and accidental constituents of the magma, rather than as having any particular bearing on the point at issue. The most notable exception to this general statement is Vogt, whose work on slags and ore-deposits is of an epoch-making character from the theoretical point of view, as well as of immense practical importance in smelting and blast-furnace practice. However, within the last few years great attention has been devoted by mining geologists to the subject of the genesis of ore-deposits, mainly because of its bearing on the question of persistence in depth or the replacement at lower levels of one ore by another, such as is known to occur in certain cases. It may be suggested, therefore, that the time has now come when it may be possible to attempt to combine the facts hitherto discovered along different lines of research into a coherent whole.

WHILE collating the plates in a recently acquired copy of the Revision of the Echini (A. Agassiz, 1872–4), I noticed with surprise a representation of complex ambulacral structure in “Echinobrissus” recens (pl. xiv a, figs. 3–4). A style of plate-grouping essentially similar to that in Echinonëus (tab. cit., figs. 7–8) is portrayed as affecting all the extra-petaloid parts of the five areas, and encroaching slightly on the distal parts of the petals. No reference to this unusual condition occurs in the text. As the proofs of my recent paper on ambulacral structures (Phil. Trans., B, vol. 209) were in my hands at the time, I was immediately impressed by the remarkable resemblance between “E.” recens and the Cretaceous Trematopygus—a correspondence by no means restricted to ambulacral plating, but involving all coronal features save the orientation of the peristome.

IN a recently published paper on the “Highest Silurian Rocks of the Clun Forest District, Shropshire” the present writer gave an account of an area where the series of “passage-beds”, marking a gradual transition from Silurian to Old Red Sandstone conditions, is well seen. The succession there is practically identical with that established by Miss Elles and Miss Slater in the Ludlow District. From November, 1918, to October, 1919, whilst engaged in a study of Belgian Tertiary rocks, I have had an opportunity of visiting some of the more important sections of the Gedinnian in the Ardennes and also of examining the palæontological collections at Brussels, Lille, and elsewhere. This work has thrown very considerable light on the English succession, and it seems desirable to give here a resumé of the conclusions reached.

OUR knowledge of the fauna contained in the Lower Devonian beds of England is extremely imperfect and unsatisfactory, partly owing to the scantiness of the material which has been collected, and partly to the poor preservation of most of the fossils themselves. The lists of genera and species given in the Survey memoir (Explan. Sheet 350) dealing with the Torquay district are not extensive, and in many cases the determination of the species or even the genera is open to doubt. Correlation in detail with the well-established and richly fossiliferous Lower Devonian of the Continent is almost impossible in such circumstances, but Kayser in 1889, on the strength of the palæontological evidence which he obtained on the spot, correlated the beds at Meadfoot with the Lower Coblenzian. The fossils which he collected and identified from this locality were the following Rhenish species: Zaphrentis oolitica, Rhynchonella daleidensis, Chonetes sarcinulata, Spirifera hysterica, Sp. paradoxa, Strophomena cf. Murchisoni, Pterinea costata.

IN the Geological Magazine for February, 1919 (pp. 59–64), one of the present writers, in collaboration with W. E. Alkins, described an exposure of a quartzose conglomerate on the north-west flank of Caldon Low. The conclusions arrived at in that paper were adversely criticized by F. Barke, Wheelton Hind, and A. Scott in a later paper in the same Magazine. These writers maintain that the conglomerate was not a contemporaneous deposit, but an assemblage of materials, analogous to that seen in the Weaver Sand-pits, south of the Ribden Mine, about one and a quarter miles away, which had filled up a solution cavity in the limestone and had become consolidated by the percolation of calcareous matter.

1. The occurrence of anticlinal folding during Jurassic times has been demonstrated by Mr. Buckman's detailed zonal work in the Vale of Moreton and in the North Cotteswolds. These anticlines are indicated on the map by marked bends in the outcrops of the Lower Jurassic formations.

2. Similar bendings of outcrops are seen at several localities in the Eastern and Southern Midlands, and the structure at one such locality—Melton Mowbray—has recently proved to be anticlinal.

3. Intra-Jurassic folding betrays itself by non-sequences and reduced thicknesses of Lower Jurassic zones along anticlinal axes. Such evidence suggests the existence of anticlinal structures in the neighbourhood of Banbury, Weedon, and perhaps also Market Harborough, in addition to the cases mentioned above.

4. Movement was probably almost continuous along some or all of these axes, at least from Rhætic to Bajocian times. Outcrops of post-Bathonian formations are not affected by the flexures, although the folding was perhaps renewed in later Jurassic or even Tertiary times.

5. Several of these lines of Jurassic folding probably follow the lines of earlier and more powerful movements. The bearing of such flexures on the structure of the Palæozoic floor is discussed.

6. Attention is called to a curious symmetry in the disposition of the Palæozoic formations on either side of a prolongation of the Pennine axis.

The diagnosis of this species given by Dr. Woodward in 1881 may be summarized as follows: Body with little or no signs of trilobation. Glabella oblong, with three pairs of lateral spines and three median spines, the anterior one apparently double. No evidence of cheek-spines. Eyes nearer genal border than in H. armatus, and rostrum more prominently developed. Thorax composed of thirteen segments with broadly expanded pleuræ; each axial ring with pair of widely separated spines. Pygidium imperfectly known. Total length of type-specimen 8 inches; breadth (measured along curve of thorax at widest part) 3¾ inches. Spines on thorax about 1 inch apart.

IT is common knowledge to all geologists interested in the Lower Eocenes of the southern part of the London Basin that, in the Oldhaven (Blackheath) Pebble Beds, pebbles of a brown quartzite are often to be found on searching amongst the rounded flints of which these beds are so largely composed. When geological parties visit sections exposing the pebble-beds of the Lower London Tertiaries, the search for these quartzites usually constitutes one of the items of the field-work to be done. A considerable number of these pebbles must, by this time, have been collected but, although their occurrence has given rise to a good deal of discussion and speculation, nobody appears, so far, to have undertaken a systematic examination of their characters and petrological affinities. The view has been propounded that the study of these pebbles would throw light on the question of the source of the material composing the Lower London Tertiary beds.

IN 1899 the Cambridge Exploring Expedition to the Malay Provinces of Lower Siam collected a few fossils and many rock-specimens at a place named Kuan Lin Soh, in the Patalung district. A small broken image of Buddha from the temple of Bah Nah containing some similar fossils was considered to have been quarried from the same beds, and it was believed that these specimens represented strata of Cretaceous age.

THE series of minute, adherent species of Brachiopoda brought together in the following discussion are usually assigned by American palæontologists to the genus Strophalosia, but recent writers have come to recognize the fact that, in America at least, the genus Strophalosia is a polyphyletic group. Dr. Stuart Weller, in his monograph on the Mississippian Brachiopoda (1914), all but recognizes the generic value of these minute shells when he points out the lack of harmony in the series of forms which he places in the genus Strophalosia.

A Point of economic importance, as well as scientific interest, has been brought out by a study of the occurrences of hæmatite in the Furness district of Lancashire and the neighbouring shores of the River Duddon in the Millom district of Cumberland; namely, that the origin and distribution of the ore-bodies, known as “sops”, is due, in large measure, to the physiographical conditions that existed in this area in post-Carboniferous but pre-New Red times. Future explorations for these profitable ore-bodies may be guided by a true appreciation of the conditions of formation, which are discussed, in somewhat scattered form, in the recently published Geological Survey Memoir on the “Hæmatites of West Cumberland, Lancashire, and the Lake District”.

LOCAL uplift and local sinking of the earth's surface have been fully demonstrated for past geological epochs. The amounts of these movements have generally been stated with reference to the present sea-level, and for the greater movements the statements of magnitudes are not seriously impaired by the fact that general sea-level itself has been shifting, upwards and downwards, through geological time. Among the causes for general or “eustatic” shifts of sea-level are: appropriate crustal movements whereby the volume of the ocean basin has been changed; delta-building and volcanic eruption on the sea-floor, the displacement of sea-water not being compensated by crustal sinking; volcanic addition of new water to the ocean; subtraction of water which becomes chemically bound during the alteration of rocks; glaciation on land, lowering sea-level by the abstraction of water from the ocean; deglaciation on land, raising sea-level; changes in the earth's centre of gravity and in her speed of rotation.

THERE has been great controversy as to whether or not there exist in Brazil diamond-bearing “pipes” such as are found in South Africa. That something of the kind should exist seems to be pretty well acknowledged, but any evidence in support of the discovery of a “pipe” has always been very meagre. The following observations made by the writer on a few mines in the neighbourhood of Diamantina, in the state of Minas Geraes, might be of interest on this somewhat vexed question.

ON the western side of Cross Fell lies a group of beds consisting of andesitic lavas and ashes, with intercalated beds of shale. The shales are tranquilly bedded, testifying to their having been deposited in quiet water. It has therefore been inferred that the igneous material is volcanic, and was poured out on a sea-floor. The beds were first described by Harkness, later by Goodchild, who gave the name “Milburn Group”, and subsequently by Professors Nicholson and Marr.

THE basement platform of Southern Eyre Peninsula consists of a series of igneous and metamorphic rocks of pre-Cambrianage. Rising from beneath the Mesozoic and Tertiary strata of the Nullarbor plains, they may be regarded as a south-easterly prolongation of the great pre-Cambrian Shield of Western Australia. The platform is for the most part within a few hundred feet of sea-level, and large areas of the region are covered by the products of long-continued weathering of the older rocks or by siliceous deposits of late Tertiary age. The best sections for geological study are those exposed along the coastline, and in the hilly areas of Hutchison and Warrow.

Mr. W. A. Richardson's paper in the December, 1919, number of this Magazine has furnished a very useful summary of the problem of the origin of flint, with some very interesting suggestions; but it cannot be allowed to pass altogether unchallenged.

In 1916 the writer published a list of the vertebrates of which remains had been obtained from the Pleistocene cave and fissure deposits of Malta. Early this year (1919) a few rather fragmentary remains were forwarded by Mr. G. Despott to the British Museum (Nat. Hist.) for identification. These are from the Ghar Dalam Cavern, from which a number of specimens have already been obtained. As some of the specimens lately received add to our knowledge of the fauna in question, it may be worth while to record the following notes.