IN an earlier paper a description of certain dolomites and calc-magnesian silicate rocks of the oldest group recognized in southern Eyre Peninsula—the Hutchison series—has been given.

For many years this portion of Egypt had remained a blank so far as its geological structure was concerned, and when the geological map of Egypt was issued by the Survey Department in 1910 this extensive area was deliberately left uncoloured. Efforts were made by the writer to interest the various parties which were mapping the topography of this region, but the fossils submitted by them only indicated the presence of beds of Upper Cretaceous age, including a facies identical with that developed in the Abu Roash hills near Cairo.

To the earthquake that ruined Lisbon on November 1, 1755, we may trace the great interest in the study of earthquakes which marks the middle of the eighteenth century, though valuable accounts of previous earthquakes had already appeared in the pages of the Philosophical Transactions. During the following year the Royal Society paid the same close attention to this earthquake that it did more than a century later to those of the eruption of Krakatoa. In 1757 an anonymous editor published The History and Philosophy of Earthquakes, in which he gave abstracts of ten memoirs by the “best writers on the subject”—Hooke, Woodward, Buffon, and Stukeley among them—followed by a summary of the observations on the Lisbon earthquake that had been communicated to the Royal Society. These are the principal sources on which Michell depended when he wrote his memoir on the cause and phenomena of earthquakes.

To illustrate the value of graphic methods when changes in a number of distinct structural elements are studied, examples may be taken from the Carboniferous corals. These are well suited to the purpose, because thin slices yield so much information and are easily measured. In Fig. 4 a diagrammatic section is shown of one of the most highly organized corals, which exhibits the following important structural units: epitheca, tabulæ, septa, dissepiments, tabellæ, lamellæ, columella.

AT the request of Mr. H. Woods, F.R.S., I have examined a small series of Echinoids belonging to the Sedgwick Museum, Cambridge, collected by the late J. F. Walker from the sand-pits on Shenley Hill, near Leighton Buzzard. Mr. G. W. Lamplugh has sent me four additional specimens from the same locality. The matrix seems to be the same in all the examples except D, and agrees absolutely with a sample of the Limestone-lentides sent for comparison by Dr. F. L. Kitchin. The age of this Limestone is a subject of controversy (see Geol. Mag., January—March, 1920), and a critical analysis of its fauna seems the only means of deciding the issue. Unfortunately, most of the Echinoids are very indifferently preserved so that specific determination is often doubtful, and in some cases impossible.

The object of the present communication is to place on record a section, apparently unique, in which the unconformity between the Millstone Grit and Carboniferous Limestone that exists in parts of South Wales and Monmouthshire is clearly displayed. The exposure was first examined at the suggestion of the brilliant worker who threw so much light on Lower Carboniferous problems, the late Dr. Vaughan. The writer had explained1 the attenuation of the Carboniferous Limestone Series in the Newport (Mon.) district as due to unconformable overstep by the Millstone Grit, similar to an overstep at this horizon that had already been observed near Haverfordwest, at the other end of the South Wales basin, by Professor O. T. Jones.1 The value of the Ifton section in demonstrating that this overstep was widespread was recognized, and photographs, two of which are here reproduced, were secured by H.M. Geological Survey. Since then the unconformity at the eastern end of the South Wales coalfield has been confirmed by the detailed examination of a large area by Mr. F. Dixey and Dr. T. F. Sibly,2 and has been found by the writer, in the course of work not yet published, to reach its greatest known extent in the Abergavenny district. Nevertheless, it seems desirable to describe the Ifton section because it is the clearest exposure known, in the whole of the South-West Province, of the unconformity between the Carboniferous Limestone and the Millstone Grit, and also on account of the remarkable inter-relations of the two formations which it reveals.

The dyke to be described in this paper has not hitherto been noticed in petrological literature, although the western part has been recorded on the map of the area by the Geological Survey. It exhibits, nevertheless, some interesting features and adds data to our knowledge of the minor intrusions of north-east England.

The Term “Cycle of Sedimentation” or “Cycle of Deposition” is not nearly so familiar in England as it is on the Continent. Whilst the teaching of the general principles forms part of most courses in geology, the application of these principles to actual successions in this country has been somewhat neglected. Attention has recently been drawn to the seasonal or rhythmic changes seen in some sediments, and to avoid confusion it is desirable to outline what is meant by the expression “Cycle of Sedimentation”.

Dr. Arthur Holmes has laid all petrographers under a debt of gratitude for his Nomenclature of Petrology, which worthily succeeds and replaces Löwinson-Lessing's Lexique Pétrographique. It represents an enormous amount of patient labour, and will provide an indispensable instrument of petrographic research. Its perusal has led the writer to consider several points in modern petrographic nomenclature which seem to need further discussion.

Since my papers on “The Superficial Deposits and Preglacial Valleys of the Northumberland and Durham Coalfield” 1 and “The Origin and Influence of the chief Physical Features of Northumberland and Durham” 2 were published, a great deal of detailed work has been done on the glacial phenomena in the two north-eastern counties by Smythe,3 Merrick,4 Herdman,5 Trechmann,6 and myself.7 As I have given much attention to this subject it may be of interest and value if I give a brief resume of my views, a general summary of the work done, and attempt to show the general sequence of the phenomena that have been described. My extensive study of the Drift in these two countries and elsewhere has convinced me of its complexity. I cannot, therefore, be dogmatic on any points, but will endeavour to show the general trend of my thoughts on the subject.

The apparent conflict in palæontological evidence is still more aggravated if the views of several able palæobotanists be taken into consideration. Plant-remains have been frequently found from the Shansian rocks in various parts of northern China. They amount to a copious flora. Numerous species are described by Newberry, Schenk, Abbado, Zeiller, Zalescky, and Yokoyama. In some cases these writers agree in assigning the flora to the Upper Carboniferous. The presence of Tœniopleris multinervis, which is said to have never been found in Europe below the Autunian stage, and a number of its allied species, such as Lepidodendron gaudryi, Calamites cf. leioderma, has, however, led Zeiller to conclude that the coal-bearing Shansian rocks in the Shan-si Province range from the highest Stephanian to the Lower Permian. Schenk also holds that the coal-bearing series of Kai-ping, eastern Chi-li, and that of Pen-hsihu, Manchuria, are of Permian age.

There appears to be a good deal of variation in the Lower Triassic succession of the different parts of Spitsbergen, even between Ice Fjord and Bell Sound, at which latter Gyronites nathorsti J. Böhm occurs in soft shales. The grey sandstones with a Lamellibranch fauna of Werfenian age from Axel Island, again, represent quite a different facies.

ABOUT twelve years ago Dr. R. H. Rastall and Mr. J. Romanes published an account of the Boulders of the Cambridge Drift. In this paper a list was given of the rock-types recognized at that time in the gravels of the Travellers' Rest Pit, situated about a mile north-west of the town of Cambridge on the Huntingdon Road. Since that time Professor Marr has paid much attention to this pit, among others, with special reference to the Palæolithic implements there found. He has embodied his results in two important papers. In the course of this work Professor Marr collected a number of interesting erratics, and the same pit has also been investigated by many geologists connected with the University, both members of the Sedgwick Club and others. During the last ten years, though the North Pit has been abandoned, the South Pit has been very actively worked for gravel, and has been greatly increased in size. In consequence of this a large amount of additional material has been collected, including many new types, while some of the older specimens, whose origin had been left indeterminate by Rastall and Romanes, have been now identified. Hence it is felt that the time has now arrived when these more recent results should be put on record.

The collections described by Mr. Spath were made during Sir Martin Conway's Expedition across Spitsbergen in 1896, and include also those then collected by Professor Garwood and presented by him to the British Museum of Natural History.

BEFORE we properly discuss the geology of China a few words on the geological work in that country will not be superfluous. Let us first of all ask the Chinese themselves if they, in the course of their intellectual evolution for thousands of years, have contributed anything valuable to our science. The inquiry into this point by the writer has so far been met by a negative answer. True, in ancient Chinese literature one often finds fragmentary suggestions and allegorical statements related to geology. As a typical example we may take the well-known expression “blue seas change into mulberry fields”. This sentence is much quoted by popular writers either for depicting the ephemeral state of worldly aflairs or for illustrating the slow, mighty change that persistently takes place on the earth. It is in the latter sense that it demands our attention. Again, there are a number of volumes both extremely ancient and comparatively modern treating of the drainage systems of China, and in some cases with rough indication of changes of the sea level. The descriptions of minerals like those in the “Bên-tsao-gang-mong” are certainly a record of incipient development of mineralogical study originated in China and by the Chinese; but as to the purpose, it was anything but geologic.

An account of the lithological succession of the rocks of the Avon Gorge was given at the Bournemouth meeting of the British Association in 1919, and a summary of the rock-characters mainly from the lithological aspect was published in the Geological Magazine (1919, p. 523). Further work has now been done, and a full account of the rocks is published in the current issue of the Quarterly Journal of the Geological Society. The following summary prepared for the above paper was considered redundant owing to the fact that the matter it contains is already incorporated in the text of the paper. In view, however, of the importance and accessibility of the Avon Section it is thought that a brief statement such as the following, in which the rock-characters are summarized firstly from a stratigraphical and secondly from a lithological aspect may be useful.

In a study of the Lower Devonian of the “Bassin de l' Eifel” the present writer established the following sequence in the Siegenian Beds (= Siegenerstufe of the Rhine) of the southern part of the Ardennes:—

Graphic methods for the comparative study of numerous observations and facts have long been in use in the exact sciences. They have also been used to some extent in those branches of the descriptive sciences which deal more particularly with the problems of heredity and variation. The purpose of the present paper is to sketch in outline a way in which they may be used in the morphological and systematic study of fossils.

The age of a concretion, relative to that of the parent-rock, must be either:—

1. Contemporaneous.—The concretion grew on the sea-floor at the same time, and at about the same rate, as the surrounding deposit was laid down.

2. Penecontemporaneous.—The concretion segregated more or less close to the surface of recently deposited sediment.

3. Subsequent.—The concretion formed after deposition had finished, and after the strata had largely consolidated, but, perhaps, before cementation had taken place to any noteworthy extent.

Of the rich collections of fossils made by Professors J. W. Gregory and E. J. Garwood, as members of Sir Martin Conway's expedition to Spitsbergen in 1896, only a few Labyrinthodont remains, so far, have been described; but through the kind offices of Dr. A. Smith Woodward, the writer some time ago was entrusted with the naming of the Cephalopoda in those collections. The Ammonites are of the greatest interest, both from a palæontological and a stratigraphical point of view; and in view of the impossibility of publishing, in the near future, a full description of the fauna, with the necessary number of plates, it is intended to give a short preliminary account of these Cephalopoda. It is matter for regret that other groups of invertebrate fossils, such as the Triassic Pelecypoda, or the Upper Jurassic Aucellids, could not be dealt with, and their detailed study, probably, would yield important results. Spitsbergen Vertebrata, on the other hand, always have received considerable attention.