Dr. F. W. Clarke truly observes in regard to the origin of chert: “No one process can account for all the occurrences of amorphous and cryptocrystalline silica, and each locality must be studied in the light of its own evidence.” (Data of Geochemistry, 1916, p. 544.)

The general features of the geology of Cyprus have been established by the work of Gaudry and of Bellamy and Jukes-Browne (1), (2); while the later researches of Professors Cullis and Edge (3) have added much to our knowledge. But in every case it has been recognized that many questions were left unsettled and many details remained to be filled in. In this connection the importance of the geological work which has been done during recent years on the neighbouring coasts of Asia Minor and Syria has been some what overlooked, though in view of the close tectonic relations between the mainland and Cyprus it deserves particular attention.

The experience of several years' teaching in the interpretation of geological maps has convinced the writer of the need for some more satisfactory method of classifying faults than has hitherto obtained.

In Teesdale and Weardale, at all exposures that have been examined, the Whin Sill is cut by a system of approximately vertical, sweeping, joint planes. These are distinct in general character from, and are on a larger scale than, the columnar jointing which is conspicuous in all vertical scars of Whin Sill. The pattern of the larger scale jointing on a horizontal surface varies with the depth within the sill; Fig. 1 shows diagrammatically the appearance at a depth of about 10 feet below the top of the sill; the inset Fig. 2, of the upper surface of the sill, shows how the joints have a more irregular course in the more rapidly cooled part of the dolerite. The joints do not usually pass from the dolerite into the adjacent sediment and Fig. 2 also shows a thin layer of baked sediment, attached to the outer surface of the sill, which the joint does not penetrate. The large scale jointing is often displaced by the small scale columnar jointing in a way that proves the large scale jointing to be the earlier. For the purposes of this paper, the early, large scale, joints will be referred to simply as the early joints. The walls of the early joints, for a distance of an inch or so, have been altered by hydrothermal solutions, to a rock which, although varying in composition with the distance from the joint, consists essentially of chlorite, quartz, and carbonate. The joint walls are usually about a quarter of an inch apart, and the space between them is filled with calcite and quartz. The calcite is present in greater abundance than the quartz which occurs in well shaped crystals of vein-quartz habit.

Jointing in rocks is a key to the strains and movements they have undergone. In rocks which have had a simple history we expect to find a simple arrangement of joint planes: in old rocks we expect to find evidence of several series of tectonic movements and hence complicated jointing. For example, in the Cambrian quartzite south of Dublin the joint planes appear to run in all directions with no obviously dominant trend. But if say fifty readings taken haphazard in one of the quarries are carefully analysed it becomes evident that the joints tend to lie in certain directions, which, if a graphical method is used, appear as “peaks” on the diagram. On examining other exposures it becomes clear that some of these peaks are of regional significance, for they recur on the diagrams for many or all of the quartzite quarries. The diagrams also show, what is not evident in the field, that in certain directions jointing is almost entirely absent.

A SUITABLE alternative title for the first section of this paper would be “Impossibilities and Geology”. In point of fact it deals more with other matters of a diverse kind than with its own proper subject as implied in the principal heading. The discussion of the theory of continental drift has now reached such a point that it is believed that the setting forth of a few useful analogies may possess some value. It is hardly too much to say that the present status of the controversy is that geological evidence continues to accumulate showing that lateral movement of continental masses has taken place, as is indeed admitted, either directly or tacitly, by many of the opponents of the Wegenerian theory, while mathematicians and cosmogonists continue to reiterate that such is impossible. Now the real meaning of this attitude is that the mathematicians and astronomers have not yet discovered a cause, which is not by any means the same thing as proving that there is no possible cause, a philosophical distinction which is very commonly disregarded. A similar state of affairs has existed several times before, even in some of the more important problems of quite modern geology.

In most systems of petrography the glassy rocks are treated in a very casual way. The names which are commonly given to them, such as obsidian, pitchstone, perlite, vitrophyre, and the like, afford no reliable indication of composition; and when a rock is partly crystalline and partly glassy, the composition of the glass is often assumed, quite unwarrantably, to be the same as that of the crystals. It is only in the Norm classification that vitreous rocks fall unfailingly into the same compartments as holocrystalline ones of similar chemical composition; and before any rock can be classified by this method, it is necessary to have a complete chemical analysis of it; which is, for many workers, a serious obstacle.

We have perhaps gone a little further into the detail of these five zones than is justified by the nature of this paper. But as we shall see later, unless the supreme importance of these east and west zones be fully appreciated, we should be at a loss to explain the peculiar arrangement of the several mountain ranges that swell forward towards the continental margin, as well as the succession of island arcs that border the continental mass of Eastern Asia.

On Sheet 339 of the One Inch (New Series) Map of the Geological Survey there is marked at Woolley, within the metamorphic aureole of the Dartmoor granite, between Bovey Tracey and Lust-leigh, a patch of “Permian” rocks. Upon inquiry the Director of the Geological Survey, Sir John Flett, informed me that this was an error and should have been marked as “Felsite”. As the rock constituting the outcrop presents unusual features and is very different from an ordinary felsite I feel that a description of it should be placed on record. Moreover, it appears to be a good example of a rather uncommon rock type.

In my account of the petrology of the Arnage district of Aberdeenshire, there appeared a description, figure, and analysis of a cordierite-spinel-hornfels from Gallowhill Brae, Arnage. This rock is composed almost entirely of cordierite, with only an accessory amount of spinel, biotite, and plagioclase. On the assumption that the analysis represented the composition of the sliced material, it was pointed out that in the cordierite of this rock, iron-oxides must replace much of the alumina and magnesia of normal cordierite.

Although raised beaches are common enough round the British coasts, the presence of such a beach on the north coast of Scotland merits description, were it only to put on record the occurrence of what is, I believe, the first undoubted example of its kind in this locality.

Mr. J. V. Harrison has entrusted me with the description of some fossil corals which be has recently collected in Trinidad. They include one remarkable coral which at first sight appeared to be Paleozoic, as its branches had a laminar structure resembling specimens of the Devonian Pachypora cervicornis in which the section has cut bands of corallites at different angles. Examination with a lens at once showed that the coral was septate, and that the resemblance to Pachypora was delusive.

Fifty years ago Charles Callaway collected some graptolites from the Shineton (Tremadocian) Shales exposed in Mary Dingle (south of the Wrekin, Shropshire); these he recorded as Dendrograptus sp., stating that he was unprepared to assign them “to any known species or to give them a new name”. The fossils were sent to Charles Lapworth who in 1879 (loc. cit.) wrote that they belonged to two different genera, Clonograptus and Bryograptus; the Clonograptus he later identified (loc. cit.) with reserve as C. rigidus Hall, whilst the Bryograptus formed a genosyntype for that then new genus. Bryograptus was defined by Lapworth about this time from two new species—(1) B. callavei, collected by Callaway from the Shineton Shales, and (2) B. kjerulfi, of which Lapworth had only seen the figures (Graptolithus tenuis) which Kjerulf had drawn from specimens found in the Alum Shales of Vaekkerö (near Oslo).

DURING recent years considerable progress has been made in the study of the palaeontology of the Coal-measures. Attention has been directed to the flora, and to the marine and non-marine faunas. Although it is undesirable to attempt a complete revision of the classification of the Coal-measures until further work has been carried out, it may be useful to indicate certain conclusions which appear to be in accord with present knowledge.

The melilite described below is an abundant constituent of a zone of reaction between dolerite and Chalk at the intrusion of Scawt Hill, Co. Antrim, Ireland. The melilite occurs both in the hybrid rock formed by assimilation of carbonate and as a constituent of the exomorphic contact zone. In the latter it is associated with spurrite, Ca2SiO4 (larnite), merwinite, spinel, and calcite. The following description applies solely, however, to the melilite of the hybrid rock.

Along the coast of North Cardiganshire, between Aberystwyth and Borth, numerous rock surfaces bearing “curious marks” have been found during the last few months. One such surface from this region has already been described, but except for a solitary fragment of rock from Transbaikalia this was apparently the only occurrence known anywhere until quite recently. The coast and inland exposures in the neighbourhood of Aberystwyth were explored at the time of the original discovery, but nothing of the same kind was found except a few indefinite traces; however, a more intensive search has now shown that these curiously-marked surfaces are by no means uncommon here.