The last two numbers of the Quarterly Journal of the Geological Society contain three communications concerning rocks which are, or are thought to be, Precambrian. Two of them are in direct attack on work of mine, and the third incidentally opposes some portion of it. The materials of any reply I may have to make are, for the most part, already published in my papers, but the bearing of these facts seems to require to be pointed out.

Taking the communications in order, the first is the Anniversary Address of the President. In this he deals, so far as my work is concerned, first with Anglesey. Sir A. Geikie states that he was not prepared by previous writings for certain results he obtained. He was much astonished to find in central Anglesey so striking a counterpart to portions of the old gneiss of the north-west of Sutherland and Ross.

Very little is known in England of the Tertiary deposits of South Africa. Some marine beds are found, as at Bathurst, where the limestone is full of teeth of Carchadon and Lamna, and shells of Turritella Ostrea, Donax, and Lucina. The shells are preserved in the Albany Museum. I was informed that these beds are 300 to 400 feet above the sea. The teeth shown to me in their worn, polished, yellowish tone rather recalled the condition of Red Crag fossils.

In a recent excursion the Liverpool Geological Society visited Norber Brow, near Austwick, to inspect the celebrated perched blocks of Silurian rock lying upon the Carboniferous limestone plateau. The visit was made in very appropriate weather during a storm of hail which added a weird element to the scene and heightened by contrast the blackness of the Silurian blocks. Since returning home I have re-read Prof. McKenny Hughes' interesting paper on the subject, and find that generally speaking my notes and measurements are in accord with his. The angularity of the perched blocks, so different to the rounded and striated erratics of the Boulder Clay Plains of Lancashire and Cheshire, and the absence of Boulder Clay, is very striking, and inevitably suggests their transportal by glacier ice probably at the last phase of the glacial period.

It is now fifty years since Charpentier told us that the heaps of Northern boulders which stretch across the plains of Prussia and Saxony mark the ancient limits of the great glacier of Scandinavia, and that the smaller debris met with farther south represents the stuff carried on by the torrents that escaped from the margin of the ice. All this he explained to his incredulous contemporaries, and now after half a century of debate, in which every other conceivable mode of accounting for the phenomena has been tried, it seems to he agreed on all hands that he was right—right in every particular—but, strange to say, it appears to be now generally forgotten that he was the man to whom we owe the first sketch of this explanation.

Among the many valleys of Daghestan that are interesting to the geologist there are none more remarkable than the channel by which the river Sulak passes through the chain of Cretaceous and Jurassic mountains which borders Inner Daghestan. Just above the entrance of this defile the four rivers Koissu unite in one stream, which in a series of cataracts tears through a stupendous chasm some fifteen miles in length, cutting the huge ridge almost at right angles to its axis.

These notes are in continuation of my former paper “On the Probable Origin of some Slates” (Geological Magazine for June and July, 1890). Since its publication I have endeavoured to obtain a little further knowledge of the constitution of the fireclays of the Coal-measures, which I regard as so well calculated to throw light on the origin of many slates, and especially I desired to get, if possible, a little more evidence as to the supposed regeneration of mica in them, in connexion with the intimately associated question of the rutile-needles.

Several species of Vertebrata are now known to be common to the Upper Lias of the neighbourhood of Whitby, Yorkshire, and the corresponding formation so widely developed in parts of Würtemberg and Bavaria. The recent discovery of another link between the two faunas in question thus seems to be worthy of placing on record. Moreover, the latest comparisons render it possible to assign to the fossil under consideration a more precise specific diagnosis than has hitherto been published; and the announcement of the discovery may lead to the recognition of other specimens besides those in the British Museum, with which alone as yet the present writer is acquainted.

In 1835 M. Charles Léveillé described a peculiar and extinct univalve shell under the name Porcellia, which he had discovered in the Carboniferous Limestone of Tournay in Belgium. Since that time the right of this name to stand has never been questioned, notwithstanding the fact of its pre-occupation by Latreille in 1804, for an Isopodous Crustacean genus, and which he rendered Porcellio. As the retaining of two names so nearly alike, differing only in their terminal letter, must constantly lead to confusion in Natural History nomenclature, it becomes necessary to suggest an alteration, and Léveillia is therefore proposed to take the place of Levéillé's genus Porcellia.

The Tonga or Friendly Islands in the South Pacific Ocean seem to have received hitherto no attention from geologists, and I can find no published information as to their geological constitution beyond the simple record of the existence of volcanoes and coral-reefs. The material of these brief notes was mostly collected by Mr. J. J. Lister, M.A., during the cruise of H.M.S. Egeria in 1889; and, through the courtesy of Captain Wharton, R.N., F.R.S., Hydrographer to the Admiralty, I have had the opportunity of examining a few additional specimens collected by Captain C. F. Oldham, R.N., Commander of the Egeria, in 1890. In view of the general account of the islands which Mr. Lister is preparing, I notice here only such points as arise directly from an examination of the specimens.

Among the vertebrate remains discovered by M. Houzeau de Lehaie in the “Craie brune phosphatée” of Ciply, is the crown of a large tritoral tooth, of unusual form and somewhat difficult of determination. A study of the reptilian teeth from the New Jersey Greensand in the Philadelphia Academy of Sciences has, however, suggested to the writer a plausible explanation of the specimen; and a brief notice of its characters may perhaps lead to the discovery of more satisfactory evidence of the animal to which it pertains.

I have lately been favoured by Dr. W. Dames with a separate copy of a communication made by him to the Neues Jahrbuch für Mineralogie, etc., dated Berlin, 18th December, 1890, in which he points out that in my Catalogue of Fossil Cephalopoda, British Museum (Nat. Hist.) part i. (1888) I have (following Eichwald) wrongly referred a certain “smooth” species of Endoceras from Reval in Esthonia, to the Orthoceratites vaginatus of v. Schlotheim,—a ribbed species.

The most remarkable earthquakes of the year 1890 were those felt in the district round Inverness between November 15 and December 14. These have been described in a separate paper. The remaining earthquakes were of comparatively slight intensity. Two or three were felt during the night of June 25–26 within a very small area to the north-east of Leeds, and one at least in Kintyre on July 24. Several slight shocks at Invergarry and Feddan, in Inverness-shire, complete the list so far as known to me, with the exception of a doubtful shock at Tulliallan in Perthshire on January 6.

It is hardly necessary to do more than refer here to the two supposed earthquakes felt on January 7 at and near Chelmsford. In a letter to “Nature,” I have given the evidence in full; and it appears to me sufficient to show that they were merely the reports of one of the great Woolwich guns.

Amongst the many useful tables given in Prof. Prestwich's “Geology”is one on the expansion and contraction of ice under variations in temperature (vol. i. pp. 139 and 183). The table in question is abbreviated from one of greater length, which was published in the year 1845 by Carl Brunner von Wattenwyll in the Annales de Chimie et de Physique, 3me ser. tome 14, pp. 369–378, under the title of “Expériences sur la densité de la glace à différentes températures.” The author of the paper referred to made an extensive series of observations upon the contraction of ice under various temperatures below the freezing-point; and he proved conclusively that, under these circumstances, the contraction of ice exceeds that of all other solid bodies that had (up to the date of the paper) been studied in this connection.

When examining the Glacial drift at Nevin, Carnarvonshire, I observed in a banded silty clay occupying the top of the cliff of drift at a point between Porth Nevin and Porth Bodeilias, an excellent illustration of my theory of Normal Faulting.

The bed in question consisted of an extremely finely laminated silty clay, sometimes called book-leaf clay, the laminations being grouped in ribands about half an inch wide and six inches apart, of lighter and darker colours, presenting a striped appearance very conspicuous from the shore. In the upper part of the bed the bands were continuous, though a little wavy : the lower part of the bed, as far as it was visible above the talus of sand, was faulted as shown in the accompanying diagram (Fig. 1). These faults simulated in a remarkable manner sections of faulted coal-fields which have been drawn from actual mining exploration and measurement.

It has long been known that certain deposits of Lower Cretaceous age lay between the Gault and the Purbeck group in the Vale of Wardour, but the absence of any good open sections, along the tracts where they reach the surface, has hitherto prevented geologists from ascertaining the exact nature and succession of the beds.

Dr. Fitton, whose account of the Vale of Wardour is wonderfully good and accurate, distinctly recognized the existence both of Wealden and Vectian (Lower Greensand), stating that certain sands, containing traces of marine shells, occurred beneath the Gault and above the clays which he regarded as Wealden.

I am aware that in describing a new apparatus for separation by heavy liquids, I am adding another item to a list which is already a very long one. My only excuse is that this particular form has the advantage of being easily and cheaply constructed from ordinary chemical apparatus, and yet has most of the advantages of Thoulet's comparatively expensive form.

Crystalline rocks containing neither felspar nor olivine have received but little or no attention, except from one or two American geologists. Dr. G. H. Williams has recently drawn attention to these rocks, of which he proposes to constitute a family of Pyroxenites coördinate with Rosenbusch's family of Peridotites; and has described from Maryland and North Carolina a type consisting entirely of monoclinic and rhombic pyroxenes, to which he gives the name Websterite. The occurrence of a similar rock in Northern Italy seems worth recording. Our specimens were collected by Mr. E. J. Garwood.

It is needless to recapitulate, for the information of the readers of the GEOLOGICAL MAGAZINE, all the incidents which are known to accompany the formation of new land by rivers, or to repeat the descriptions which have been given of the more remarkable instances of them, such as those of the Nile, the Mississippi, the Ganges, the Rhone, the Po, and the Danube. These have been scientifically discussed long ago, by Lyell in his Principles. The object of this paper is rather to suggest how a careful collation of such facts as may be learned in connexion with the formation of modern deposits at the mouths of great rivers, or in great estuarine areas (such as the Wash), which receive a number of streams from widely-extended inland catchment-basins, may throw light upon the history of older formations of the same kind, and more especially of those of Tertiary times, during which many important changes were wrought in the physiography of the continent of Europe.

I do not think geologists who have studied the Himalayas will be disposed to agree with Mr. Howorth (ante, pp. 97–104, 156–163) that those mountains have come into existence since the time when the Mammoth flourished in Siberia. It is quite possible that the Himalayas are higher now than they were in Pliocene or even in Pleistocene times; but the geological evidence, so far as it is known, is, I think, in favour of the view expressed by Mr. R. D.

As a sequel to my recent paper on new specimens of Dendrerpeton, I have thought it desirable to reproduce by photogravure, for comparison, the type specimen of Hylonomus Lyelli now in the collection of the Geological Society of London. The reproduction (Plate VIII.) is of the natural size, though less distinct than in the original. Though the bones are scattered, this specimen enabled me, by measuring the separate bones and adding the cuticular scales found on other specimens, to restore the animal in my “Airbreathers of the Coal Period.”