After the expiration of twelve months, Mr. A. R. Hunt, who was present at the meeting of the British Association at Belfast, has published in your September number a criticism on my address. His paper deals with a variety of matters with which I need not concern myself. His remarks on tourmaline have reference to another author, and not to anything I have written on that subject. He also passes strictures on what he calls “incidental geology,” but as he includes Lord Kelvin and Canon Bonney with me in his condemnation, I can only congratulate myself on being in such good company.

The objects of this note are three: (1) to call attention to the essential chemical similarity between laterite and bauxite; (2) to offer a theory for the formation of laterite in the moist tropics; (3) to suggest an explanation for its spontaneous dehydration.

(1) Laterite has generally been referred to as a ferruginous clay; but if the term clay is restricted to substances having a basis of hydrous silicate of alumina, this definition is incorrect. The alumina in laterite exists, as it does in bauxite, in the form, of hydrous oxides. Kaolin must thus be removed finally from the list of weathering products; it is formed generally, perhaps exclusively, by the action of subterranean vapours on aluminous silicates. This conclusion necessitates a re-examination of many so-called argillaceous substances; many doubtless include the kaolin already existing in the kaolinized aluminous silicates before they are exposed to the weather. But it is probable that some of the red clays of past geological ages, formed under subaerial conditions, contain free hydrous oxides of alumina; and for those that are shown to contain hydrous silicate of alumina, it would be well to test the possibility of a secondary reunion of aluminic hydrate and free silicic acid.

(2) To account for the fact that an aluminous silicate undergoes a more complete disintegration under tropical conditions than under the deep-seated and presumably high-temperature conditions of kaolinization, the writer suggests that laterite is due to the agency of lowly organisms, possibly akin to the so-called nitrifying bacteria.

Plutonic rocks of acid composition are very extensively developed in Africa south of the Equator. These rocks present many features of interest, and, especially under the microscope, many minerals may be recognized besides the usual quartz, felspar, and ferromagnesian constituents. Thus the granite of Cape Town itself is remarkably rich in accessories. Tourmaline, in particular, is very abundant in places. In thin sections it is of a yellowish brown colour frequently bordered and zoned with pale blue, while some crystals show alternate bands of yellow and brown. Cordierite also appears to be sometimes present in the normal granite. It may be quite fresh and almost indistinguishable from quartz, while in other cases it is entirely replaced by the yellowish micaceous ‘pinite’ pseudomorphs. The intermediate stages of the alteration are well shown, while it is interesting to note that it seems to have crystallized sometimes before and sometimes after the felspar.

At Towan Head and in the cliffs of Fistral Bay, near Newquay, there is seen, at a few feet above high-water mark, the remains of the Pleistocene Raised Beach. This consists of pebbly beds associated with ancient blown sands, sometimes of considerable thickness. Above this series of deposits comes the Head or Rubble Drift, formed during a greater elevation of the land. These beds have been fully described by many authors—De la Beche, W. A. E. Ussher, Sir Joseph Prestwich, and others. While capping the Head and Raised Beach, and on the top of the cliff, there is a series of more recent Æolian sandy beds.

About a year ago my friend Professor Dobbie, of the University College of North Wales, drew my attention to the remarkable experiments of Sir W. Roberts-Austen (whose premature death we must lament as a very great loss to science) on the diffusion of solid metals, suggesting that they might have some geological application. The phenomena referred to in this paper, in which I have been very keenly interested ever since my work as a Geological Surveyor in Eastern Sutherland, occurred to my mind at the time as a probable case; but after some reflection certain difficulties began to appear, and I put the subject aside for a while. The very suggestive address of General McMahon to the Geological Section of the British Association at Belfast has reawakened my interest; and it seems to me worth while to put forward some considerations on the matter, somewhat speculative indeed, but which may perhaps be of service in stimulating research on a fascinating though difficult subject.

An easy walk from Lourdes through Lésignan, Paréac, Orincles, Leyrisse, and Bénac, to the return station of Ossun, traverses the entire outcrop of the Upper Cretaceous Flysch, lying between the abrupt uprise of the Cenomanien limestone at Lourdes and the Danien that skirts the Tertiary plain towards Tarbes. The age of this Flysch is admitted; every objection regarding it has been successively abandoned; and its appearance, composition, and characteristic fucoids are as typical at Lourdes as at any point within fifty miles on either side. By insensible gradations it passes repeatedly from fresh marly shale with characteristic fucoids into micaceous schists that have been classed as Cambrian. Portions of a sandy character acquire vivid colouring and pass insensibly into a rock indistinguishable from decomposed granulite, while preserving their original bedding. Such changes occur on either side, or on the prolongation, of extensive lenticular intrusions of solid granite, which cross the indicated route between Paréac and Orincles and between Orincles, Visker, and Bénac.

In High Teesdale, on certain hillsides, the structure of which is in most respects clear, the observer is struck by the disappearance of some, generally constant, limestone which ought naturally to occur. The limestone most usually missing is the Great Limestone, which, with the exception of the Melmerby Scar Limestone, is the thickest of all in the dale. Though the ground is almost free from peat and drift, and plainly shows the banks formed by the Four Fathom Limestone and Firestone, there is yet perhaps neither bank nor ‘shake-hole’ (swallow-hole) to represent the Great Limestone. In the cases referred to the difficulty cannot be accounted for by supposing that the limestone along its outcrop is thrown out by a fault, for the outcrops of the beds above and below can be followed round the hill without interruption.

In the course of conversation with Professor J. Park, the Director of our School of Mines. I first heard of the occurrence of a gigantic pedunculated Cirripede in certain Tertiary deposits on the east coast of the North Island of this colony. I then wrote to Mr. T. F. Cheeseman, the Curator of the Auckland Museum, in which some remains were exhibited: in answer to my request, Mr. Cheeseman very generously loaned me these remains, and the following notes are founded on them. I will here express my thanks to this gentleman for the readiness with which he has, in this and other instances, complied with my request for the loan of specimens out of his museum. But these few fragments do not represent all that is known of the animal; for I understand that abundant material, collected by Professor Park during his geological survey, is entombed in boxes in the Colonial Museum at Wellington, and Professor Thomas, of Auckland, also possesses, as he informs me, a fair supply of valves, collected by himself.

I have, however, not been able to examine either of these collections. And although the present contribution is very incomplete, yet I hope that it will stimulate the possessors of better material to supplement or correct my remarks; at any rate, it will serve to direct the attention of European geologists and zoologists to the existence in late geologic times of a Cirripede remarkable chiefly for its gigantic size, far surpassing any member of the group hitherto, known to science.

The above paper, read before the Geological Society on the 27th May last, having just reached my hands, with the discussion, I trust you willallow me to make some observations thereon, not having been present on the occasion. As my name does not appear once throughout the paper it might at first sight be considered unnecessary, if not impertinent, for me to take any direct notice of its contents. I must therefore ask permission to state the reasons for this communication as briefly as may be, and they may be summed up in a single sentence—that, being responsible as the officer of the Survey who carried out the geological mapping of the Cotteswold Hills and of the outlying Bredon Hill, I cannot allow reflections on its accuracy to pass unanswered.

Some time ago my friend Mr. Jukes-Browne asked me to examine some sand, with a view to ascertaining whether it was derived from Dartmoor. Dartmoor quartzes have so many specific characters that it is often easy to say that a quartz is not derived from that region; but owing to the fact that quartz-veins have not been studied, it is usually impossible to say whence various sands have in fact come.

A Good deal has been written on the permanence of ocean basins, but about the permanence of river valleys I have never noticed any discussion. The causes which tend to maintain the existence of a river valley are indeed obvious and simple; probably this simplicity and obviousness are the very reasons why so little has been said. Yet even if superfluous it may be interesting to bring together some of these causes, such at least as have come into my mind.

What actions can even temporarily obliterate a channel cut into the surface of the land? Submergence followed by re-elevation: what will that effect? During submergence sediment may be deposited. If this be deposited as a mantle of equal thickness over the whole bottom, the surface on re-elevation would have the same shape as before; hills and valleys would reappear of equal relative heights and depths. Probably, however, the amount of sediment would be greater in greater depths: more would be deposited in valleys than over hills. Then on re-elevation the surface would appear with features smoothed down, but not obliterated. Where a valley had been, a valley would again be; less deep, but with a fall in the same direction, tributaries in the same position, and the same catchment basin as before. Rain and rivers would resume their old courses and their old work; the valleys would be the same as before. Imagine even the most improbable case of a sedimentation such as should bury hills and valleys alike; let every feature vanish as a path is hidden beneath a sheet of snow; even then the valley would reassert itself.

While appreciating and agreeing with the valuable work done by Dr. Irving and Professor Hull, dealing with the New Red rocks of South Devon, as set forth in their papers on this subject in the Quart. Journ. Geol. Soc., there is only one point in which I differ from these authors; it is in relation to the rocks forming the base of the Keuper in this area.

In the last of these papers both authors agree to regard certain breccias occurring at the mouth of the river Otter, and again at the mouth of the river Sid on its eastern side, as the basement beds of the Keuper.

The basement breccias of the river Sid section, as explained by them, are the Otterton breccias again brought up, and repeated by the fault which occurs at the Chit rock, where the sandstones on the east side of the fault are brought up against the Keuper marls on its west side.

The breccias near the mouth of the Otter have been described by Dr. Irving as calcareous or dolomitic breccias, or conglomerates, which I think quite a correct description of these beds. This description, however, certainly does not apply to the alleged breccias on the left bank of the Sid, to which I shall presently refer.

The Otterton breccias or conglomerates have been traced inland by Dr. Irving to various localities, all of which I have visited and have found correctly described. The breccias in the inland localities are, however, all along the strike of the Otterton Beds, and not in any case, along the strike of the alleged breccias said to occur in the Sidmouth section.

In the recently published volume of the Memoirs of the Geo-logical Survey of Scotland, “The Geology of East Fife,” by Sir Archibald Geikie, it is argued that since the time when the 100 feet terrace was under the level of the sea there has been no depression of the land in the Firth of Tay, only “a continuous chronicle of gradual, if intermittent, uprise” (p. 321); also that “no trace has survived of any late deposit overlying the peat, so that we cannot be absolutely sure of the position which this sheet of vegetable matter would occupy if all the Post-tertiary deposits of the district could be grouped in chronological order ” (p. 318).

In the face of this statement by such a high authority it seems to be very desirable that the details of a section in post-Glacial beds, exposed in digging the foundations of the new Post Office in Dundee, should be recorded in the pages of the Geological Magazine.

The present notes are based on field observations made in 1900. The section described is now obscured.

Corundum is abundant in the gem-bearing gravels of Ceylon, but with the exception of the case here described no localities are known where it occurs in sitû; the present occurrence is therefore of considerable interest, although not very satisfactory in itself.

Crystals of corundum were found in the surface soil on a piece of land known as Tenna Hena, and situated east of Kandy, and three-quarters of a mile north-east of Talatnoya bridge. The exact spot is shown in a map accompanying a paper on the crystalline limestones of Ceylon (Quart. Journ. Geol. Soc, 1903, vol. lviii, pl. xiii). A small excavation had been made, and a few pounds of corundum extracted and sold for use as emery, before my visit to the spot. All the rock exposed was decomposed, and crumbled in the fingers, being in a condition resembling sand. I therefore carried on an excavation for two months, hoping to reach hard rock suitable for microscopic examination, but although a depth of about 30 feet was reached, no sufficiently hard rock was found.

At the corundum pit the ‘beds’ of granulite dip northwards at a high angle. A conspicuous soft yellow micaceous band 7–3½ inches wide marks the position of the sapphire-bearing zone. The sapphires occur in fair abundance in a less decomposed felspathic rock occupying a few inches on either side of this yellow micaceous band in the upper part of the shaft, but on the south side only in the lower part. The associated types of granulite are chiefly acid leptynite.

In the collection of Mr. Alfred Brown, of Ariwal North, there is a fairly complete skull of a moderate-sized Stegocephalian which differs very considerably from that of any form hitherto described. The specimen is in a sandstone matrix. Owing to a crack produced by weathering practically all the cranial bones adhered to the counter slab when an endeavour was made to display the remains. The sculpturing of the bones is thus hidden, but the sutures are for the most part distinctly seen. Fig. 1 represents a slightly restored view of the upper side of the skull. The most striking features are the great breadth of the skull and the relatively advanced position of the orbits. In these respects it makes a slight approach to the condition found in the American genus Diplocaulus. There is no distinct notch in the post-temporal region, as in most Stegocephalians, and there are no ‘epiotic’ cornua. There are two rudimentary cornua on the posterior cranial border, but they are formed by the so-called ‘supra-occipital’ bones. In the middle line between the frontals and nasals is a median bone, probably an ethmoid. I fail to detect a supra-temporal element as distinct from the quadrato-jugal, which is of large size.

After transferring the collections to the new building in the year 1892, more than ten years work was necessary to finish the arrangement of 251 cases, which occupy seven large rooms. Now nearly all this labour is completed, and those who are interested in palæontology will be glad to learn some details as to the general arrangement of the Museum.

In the Geological Magazine for June of this year I proposed the new specific and generic names Anthracosiro woodwardi for a Carboniferous Arachnid represented in the British Museum by a single specimen (No. 1551) from Coseley, near Dudley, that formerly belonged to the collection of Mr. Henry Johnson. A further communication from Dr. Friĉ, of Prague, drew my attention to three additional specimens, with the same history, numbered 1554, 1555, and 1556, and ticketed Eophrynus, sp. nov. No. 1555 is the under-side of a scorpion, without the tail; the others are referable to the genus Anthracosiro.

Concerning the origin of the Mosasaurs three altogether different views exist: G. Baur regarded the Mosasaurs as highly specialized aquatic Varanoids; Boulenger is inclined to trace their origin back to the Neocomian Dolichosaurs; and Osborn, in a recent paper, doubts that Varanids and Mosasaurs sprang from a common stem, and regards the latter as “a very ancient offshoot of the Lacertilia.” Some Lacertilia found in recent years in the Lower Cretaceous of Dalmatia, and not yet fully compared with the Mosasaurs, will, I believe, throw fresh light on this subject. Among the fossil Lacertilia found in Dalmatia two types can be distinguished, namely, Dolichosaurs and Aigialosaurs, the former including the genera Dolichosaurus Owen, Pontosaurus Gorjanovic-Kramberger (= Hydrosaurus lesinensis, Kornh.), Acteosaurus Meyer, and Adriosaurus Seeley; the latter, Aigialosaurus G. Kramberger, Garsosaurus Kornh., Opetiosaurus Kornh., and perhaps also Mesoleptos Cornaglia.

The following notes were made during the little time I was able to devote to leisure while staying at Camborne in order to study the methods there employed of mining and dressing the tin-bearing rock. They therefore deal only with places within easy reach of that town.