During the long period of time comprised in the history from the Cambrian Period onwards, the slow and persistent evolution of plant and animal life went forward and left ample record in the rocks. To warrant a belief in organic evolution, we are no longer solely dependent on reasoning founded on existing organisms or on the facts of their ontogeny and distribution. As M. Marcellin Boule says in his work on Fossil Man, “… pour tout ce qui a trait à l'évolution des êtres organisés en général, le dernier mot doit rester à la Paléontologie quand cette science est en mesure de parler clairement. Les plus fins travaux anatomiques, les comparaisons les plus approfondies, les raisonnements les plus ingénieux sur la morphologie des êtres actuels ne sauraient avoir la valeur démonstrative des documents tirés de la roche où ils sont enfouis et disposés dans leur ordre chronologique même.” Although we are only too painfully aware of the innumerable chances that conspire to prevent an animal or plant from securing immortality by preservation as a fossil, the finding of better preserved material, the more skilful preparation of it for examination, and the application to it of refined biological methods, such as careful dissection and the serial sections of Professor Sollas, are giving us more complete and accurate knowledge than ever before. It may now be confidently stated that many of the most crucial links in the chain of evolving life are in our hands, that they actually lived in the past, and that their fossil forms show their relationship to their predecessors and successors. The time has come when Darwin's famous chapter on the “ Imperfection of the Geological Record ”, an apology written with the most balanced criticism and unbiassed judgment, should be re-written and revised.

The Aru Archipelago consists of a group of some eighty low islands which rise from the shallow sea between western New Guinea and Australia. They have been interpreted by Wichmann (1887, pp. 120–1) as the south-eastern members of an arc, to which he assigned also the Sula, Obi, and Misool Islands, and part of the south-western coast of New Guinea. This arc he regarded as the easternmost of three arcs at the eastern end of the Banda Sea. This view has been adopted, amongst others, by Koto (1899, p. 97, pl. i). The Aru Islands consist, according to the account in Verbeek's “Molukken Verslag” (1908, pp. 9, 464–5, fig. 420), of an almost horizontal limestone plateau, which has been broken by uplift into more than eighty pieces.

It must inevitably happen sometimes that an author does not quite convey to his readers the whole of his own conception of a subject. It may be perhaps that certain objects in his mental picture are to him so obvious as to be unworthy of emphasis, and he is apt to forget that to his readers no part of the picture is, in the first instance, obvious. From the recent paper by Messrs. A. K. Wells and S. W. Wooldridge (“The Mechanism of Sedimentation Cycles”, Geol. Mag., Vol. LX, December, 1923, pp. 545–50), it is evident that I have failed to convey, to them at least, the whole of my conception of the Anglo-Franco-Belgian Basin. I apologize, therefore, to readers of my Introduction to Stratigraphy for any lack of clarity, and I should like to thank Mr. Wells and Mr. Wooldridge for bringing the matter into the light of day and allowing me an opportunity of stating very simply my ideas, all of them already published, on the geography of the Anglo-Franco-Belgian Basin in Eocene times. Perhaps had my critics, before rushing into print, read pages 278–9 of my book as well as page 267, the occasion would never have occurred.

The main conclusions of the paper may be briefly stated thus:—

1. The deposits, which are of neritic facies, possess a characteristic and peculiar mechanical and mineralogical composition, differing therein from any other British deposit.

2. They exhibit a general constancy in grade from the Dorset coast to the Cotteswolds. Within this limit they conform to two chief types containing respectively 40 to 50 and 60 to 80 per cent, of the very fine sand grade (greater than 0·05 and less than 0·1 mm.). No variation of mechanical composition with hemeral change can be observed.

3. The sands are blue and glauconitic in depth. At the surface they are decalcified and are yellow and brown as a result of oxidation. Minerals such as pyrite and pyrrhotite occur only in depth.

4. The mineralogical composition indicates an abundance of highly angular brownish-pink to colourless garnets (possibly derived from rocks like those of the Lizard), but few red or purplish-red varieties; also of micas (including a pseudo-uniaxial, pale-green to colourless variety), together with chlorite, chloritoid, kyanite, staurolite, orthoclase, and microcline.

5. Tourmaline is only moderately common and is always the grey-brown variety.

6. The abundance of titanium-minerals is characteristic of the deposits. Red and yellow varieties of rutile and sagenite-webs are exceedingly abundant, and anatase, brookite, and sphene are locally so. A reciprocal relation may exist between the occurrence of sphene, ilmenite, and the oxides of titanium.

7. Epidote and glaucophane are rare.

8. Chlorite, chloritoid, glaucophane, kyanite, and staurolite increase in quantity as the deposits are traced southwards.

9. A change in lithology and mineralogy sets in as the deposits are followed north-eastwards into the Midlands and Yorkshire.

10. The sands differ markedly in petrology from the various Palæozoic rocks of Wales and the West Country, from the Trias, and from the Cretaceous and Eocene of Devon and Dorset.

11. The Ordovician, Domerian, Toarcian, and Aalenian of Normandy and Brittany have been examined petrologically for purposes of comparison, but show little resemblance to the sediments under discussion, having been derived locally from the Palæozoic and pre-Cambrian rocks.

12. It is concluded that the Lias–Inferior Oolite sands have been derived from the south or south-west, notably from rocks like those of western Brittany.

13. The rise of the Mendip axis was not sufficiently complete at this time to cut off the supply of sediment from the south or south-west. The deposits north and south of the ridge have the same general character.

In some recent papers dealing with Tithonian ammonites, the writer included zonal schemes of the higher Jurassic, up to what he considered the topmost horizon, namely the privasensis zone. The correlation of the Mediterranean ammonites with those of the “boreal province” or Pavlow's “Aquilonian” was also discussed. Since this author had recorded “Aquilonian” Craspedites and Garniericeras from the Speeton Clay and Spilsby Sandstone, the inquiry naturally led to a revision of the ammonites of the Neocomian of Yorkshire and Lincolnshire. A critical examination of the ammonite horizons at the Jurasso-Cretaceous border-line seemed specially invited because in our most recent textbooks Yorkshire strata obviously well up in the Cretaceous are still included in the Jurassic; and it was also deemed useful to link up the table of Tithonian ammonite zones, above referred to, with that of the Aptian, given by the writer in a paper on the “Ammonite Horizons of the Gault and Contiguous Formations”.

Shortly after the appearance of my paper on “ Some Cretaceous Echinoidea from Jamaica ” (Geol. Mag., Vol. LX, 1923, p. 199) Dr. C. T. Trechmann returned from a further visit to the Island, bringing with him a considerable collection of Echinoids. These he has entrusted to me for examination and report, possibly with the hope that the Cretaceous specimens might induce me to change my heretical opinions as to the horizon present! Once again I have to express regret that I can only repay his kindness by expressing views similar to those previously given, and this time with far greater precision than before.

I have for several years paid attention to glacial phenomena near Coniston, and some of my observations seem to be worth recording.

All students of the Thulean (Brito-Arctic) province of igneous rocks will be interested to learn of the landing effected on the islet of Rockall in June, 1921, by Dr. Charcot, of Antarctic fame, at the instigation of Professor A. Lacroix, of Paris, who has recently described the new material thus obtained. The writer believes that an account of the results so far achieved will be welcomed by British workers.

This small, though extremely interesting area of Carboniferous Limestone is situated about 4 miles north-east of Bridgwater and ¾ mile north-east of the village of Cannington.

For several reasons it has attracted a large number of workers. Fossils are scarce (at first the mass was thought to be unfossiliferous), and hence for a long time the “Devonian or Carboniferous” question of age was a bone of contention. Also, the final acceptance of its Avonian age showed that productive Coal Measures were probably deposited in the area between the Mendips and the Quantock Hills.

Remains of arthropods are among the rarest of fossils in the Coal Measures. Rare as they are, however, they have been recorded in some numbers from nearly all the principal coalfields, including those of the British Isles, the Continent of Europe, and North America. But of the larger British coalfields, that of Northumberland and Durham appeared till recently to be conspicuously poor in fossil arthropods.

An examination of sections of the silicified wood from the King's Arms Pit, Tiptree, revealed at once that the structure was of the Dadoxylon type, and the absence of growth rings strongly suggested affinity with the Palaeozoic woods included in that genus, many of which are allied to Cordaites rather than to the araucarians. Among known silicified woods, a close comparison was possible only with those from the Corley (Enville) Group of the Midlands, now regarded as probably Upper Carboniferous, and not Permian.

A few years ago Mr. Carruthers described an aberrant coral, Cryptophyllum hibernicum, from the Lower Carboniferous of Bundoran, Donegal. Cryptophyllum occurred in the Lower Calp shales, which are considered to be about at the horizon of Vaughan's C2 to S1 beds. Another aberrant genus, Heptaphyllum, also from the north-west of Ireland—Lower Carboniferous shales, Sligo—forms the subject of this paper. Cryptophyllum is remarkable, first for the manner in which the earlier major septa appear—irregularly, and nearly simultaneously, instead of regularly, and in consecutive pairs, as is typical for Rugose Corals; and also in the development of only five septa instead of the normal six in the earliest growth stages. Heptaphyllum, as its name implies, develops seven septa in the young corallum. It resembles Cryptophyllum in having an early aseptate corallum, and in the way in which the earlier septa appear.

1. The comparatively shallow Chalk Seas of the Northern Hemisphere owed much of their clarity to their situation in a geographical belt where matured desert figured as the typical associated continental form.

It was hoped that this section would have been presided over by Dr. C. W. Andrews. He had, indeed, accepted the invitation of the Council to become President, but the state of his health later compelled him to resign. His untimely death has deprived our science of a widely travelled and most talented geologist and a vertebrate palaeontologist of world-wide distinction.

My attention has recently been called to some very interesting comments on the problem of the delimitation of the Silurian and Devonian systems, which were made by Dr. Elles in her Presidential address to Section C of the British Association at Liverpool. I am so heartily in agreement with all the principles of the modern classification of strata, as laid down by Dr. Elles, that it seems of advantage to recall very briefly how closely these principles are adhered to in using the Ludlow Bone-bed as the local base of the Devonian in England.

During the course of a recent excursion of the Cambridge Sedgwick Club to the Coniston District, under the guidance of Professor J. E. Marr, important evidence was obtained upon the relationship of the Coniston Limestone Series to the Borrowdale Volcanic Series. A visit was paid to the area south-west of Torver Beck, when, after Professor Marr had pointed out the marked difference between the strike of the Coniston Limestone and that of the underlying Borrowdale rocks at High Pike Haw, the actual strongly discordant junction was located by Professor O. T. Jones and the writer. This was found to be one of unconformity and not a fault, and was traced by the party for some distance.

From time to time during the last fifteen years the specimens described below have been put into my hands for determination and description. In the hope of obtaining better specimens, which would explain more fully their structure and affinities, the publication of any notes on them has been repeatedly deferred, but further delay seems undesirable.

It is hardly necessary to point out how very important it is that those on whom falls the onus of naming a rock should decide which is the most fitting name only after very careful consideration. Some there are who profess to be above the petty worries of nomenclature, and from these only a loose application of rock names can be expected. This is liable to mislead those dealing with problems of petrogenesis, who are justified in assuming that those competent to carry out geological research are also competent to apply correct names to their discoveries. That this is often not the case can be easily demonstrated from quite recent papers. The difficulty arises from two causes: the lack of a system of rock classification which in any sense approaches the ideal, and a desire for brevity. Concerning the first difficulty it is sufficient to say that little advance in placing the nomenclature of rocks upon a firm and common basis is possible until one universally recognized system of rock classification is in use. It is still open for investigators to choose, without any set standard, which of several variable characters of a rock should be the criterion upon which the systematic position of the rock depends. Thus, one writer places mode of occurrence before micro-structure, while his neighbour deems it wise completely to ignore mode of occurrence and makes micro-structure the deciding factor.

The diversity in mineral composition of metamorphic rocks can be regarded as the resultant of two independent variables, first of the ultimate composition of the rocks, and secondly of the grade of metamorphism, or the particular pressure-temperature conditions under which the rocks have arisen. It is clear that these two variables may well form the basis of a classification of rocks of metamorphic origin.

The present paper deals briefly with the historical aspect of the boundary between the Pendleside Series and the Millstone Grit Series in the Roches district and surrounding country of North Staffordshire some 4 miles north-east of Leek; and particularly with the term “ Farey's Grit ”. It seems to me probable that the difficulties as to limitation and classification of these divisions of the Carboniferous System are by no means limited to the small area with which I am familiar. The substance of this paper is derived from the works listed at the end, and has formed itself as a result of attempts to map the rocks in detail.