It may be of interest to the readers of the Geological Magazine to know that the specimens collected by Mr. H. E. Strickland during the years 1835–6 in the Ionian Islands, the Bosphorus, and the neighbourhood of Smyrna are now preserved in the Sedgwick Museum, Cambridge.

Edrioaster bigsbyi was first made known by E. Billings in June, 1854, and was referred by him, though with some doubt, to Agelacrinites. He gave no specific name, but regarded his fossils as identical with the specimen found by Bigsby at the Chaudière Falls and described by G. B. Sowerby in 1825 (see Study III), and as “almost identical with A. Buchianus” of Forbes, 1848 (see Study II). This series of papers by Billings contains several important observations and reasonings not reproduced in those later more official publications of his to which alone subsequent writers seem to have gone for information. From the original account it is clear that the specimens there called Agelacrinites were the same as those which Billings described in 1857, under the name Cyclaster bigsbyi. The misapprehension that caused Billings to apply to his new species the trivial name bigsbyi has already been dealt with in Study III; the species has nothing to do with the specimen found by Bigsby. In 1858 Billings discovered and pointed out his error, and, realizing further that the generic name Cyclaster had been taken by G. Cotteau for a sea-urchin a few months before his own use of it, he redescribed the species under the name Edrioaster bigsbyi. The independence of the genus itself was denied in 1860 by E. J. Chapman, who referred the species back to Agelacrinites. The textbook writers, however, generally accepted Edrioaster, and no change was made in either name or description until Professor Haeckel in 1896 thought fit to alter the name to Edriocystis.

The special interest of the island of South Georgia depends on the evidence it promises as to the geological history of that part of the Southern Ocean which lies south of the South Atlantic. According to the well-known views of Professor Suess, South Georgia is on a continuation of the mountain line of the Andes, which at the southern end of South America bends eastward along the northern margin of Drake's Sea and continues 30° to the east, where it turns southward; it completes a great horseshoe-shaped course by passing through South Georgia and returning westward through the South Orkneys to Grahamland.

Of the Cirripedes obtained by the late Mr. F. Mockler from the Chalk Marl of Cambridge, two species, Zeugmatolepas mockleri. Withers, and Calantica (Titanolepas) tuberculata, Darwin, sp., have already been described and restorations given. The remaining material consists entirely of disconnected valves, and among these are (1) a number of valves referable to Pollicipes glaber, F. A. Roemer; (2) a few valves of P. rigidus, J. de C. Sowerby, together with some valves of a new species which is probably related to P. rigidus; (3) an important series of valves belonging to several species of Scalpellum allied to S. arcuatum, Darwin, and S. fossula, Darwin; and (4) some valves that do not belong to any of the species already mentioned, and which it will be convenient to describe here.

This boring, though confined to the Kimeridge Clay, is of some interest, partly because it has proved the thickness of that clay to be much greater than it was supposed to be in this part of Wiltshire, and partly because it has yielded a species of Aporrhais or Harpagodes which has not previously been found in England.

Everyone knows that ice floats in water, is able to carry some amount of materials attached to it, and if lifted by rise of the water-level is able to lift them with itself. Lyell describes this in the Principles (ch. xvi, xxxi), and probably it is mentioned in every textbook. But ice is also able to lift attached materials without rise of the water-level. It requires no tides, no floods; it can lift without external aid, by its melting alone.

When a crust of ice 1 foot thick has formed on a sheet of fresh water it floats with its upper surface about an inch above water-level, its lower surface about 11 inches below. If by any cause this ice-crust is melted over its upper surface, the products of melting flow off, the upper surface sinks a little, but the lower surface rises through about eleven-twelfths of the thickness melted off. Take an ice-floe uniformly 6 feet thick: its lower surface will be floating, if the water be fresh, at about 5½ feet below water-level. Suppose it reduced by melting over the upper surface till only 6 inches thick, the lower surface will now be about 5½ inches below water-level; this lower surface will accordingly have risen more than 5 feet. If any objects or materials were attached to that lower surface they will have risen with it: they will have been lifted. This is undeniable and obvious. It is undeniable and obvious that ice is able to lift materials by simple melting, independently of any other power or action.

One of the drawbacks of working in a distant land is that the valuable help of the friendly critic is rarely available, and that, therefore, however strongly the truth of conclusions arrived at may be felt by oneself, it is impossible to expect readers in England to accept without reserve statements that may with perfect justice be said to require corroboration by other observers. I have felt the force of this consideration particularly in the case of the clays of the Malayan Gondwana rocks, which I have described in more than one publication; and as the conclusions in those descriptions are so far removed from what was to be expected in a country where recent alluvium was until quite lately believed to be the most important formation, it is, I think, advisable to place on record in some detail any corroborative evidence that may be brought to light. An additional reason for this course is the constant change in the mine-sections owing to mining operations, and also to the rapidity with which sections weather.

In my account of the Lower Carboniferous rocks of the North-West of England, published in 1912, I figured an organism, probably the thallus of a calcareous alga, which plays an important part as a rock-builder at the base of the Seminula gregaria sub-zone in Westmorland and Lancashire. More recently, at the meeting of the British Association in Birmingham, I pointed out the need of some distinctive name for this important form, and suggested for it the generic name of ‘Ortonella’, from the village of Orton, near Tebay, in the neighbourhood of which this fossil is specially abundant. Two other structures were mentioned at the same time which occur constantly in microscopic sections of the Lower Carboniferous rocks of the North-West of England and elsewhere. The first of these was alluded to under the general descriptive term ‘festoon structure’, and the other was referred to Gurich's somewhat obscure genus Spongiottroma. In view of the zonal value of these organisms in the North-Western Province and the probability that they will be found to be widely distributed in the Lower Carboniferous rocks elsewhere, I propose here to give a somewhat fuller description of these forms than could be attempted in the limits of a presidential address.

Early in the year 1913 the Copenhagen Museum of Mineralogy and Geology issued a report upon a most interesting deep boring in the Chalk at Gröndal, just outside Copenhagen. The results are so striking in respect to the thickness of chalk passed through that it appears desirable to bring them before the notice of English geologists. The estimates of the thickness of the English Chalk which are considered to be the most reliable are those given by Rowe from measurements of the various zones in the Isle of Wight and Dorset. These are approximately as follows:—

In certain geological horizons where there is evidence of continuous deposition of salts from the waters of inland basins, gypsum and anhydrite are found closely associated, while in other similar horizons gypsum may occur with apparently no trace of anhydrite. Some Upper Silurian occurrences in North America, the Lower Carboniferous of Eastern Canada, and the Zechstein of Northern Germany are illustrative of the association of both minerals, while in more recent gypsum horizons anhydrite seems to appear less frequently. Even in the one horizon anhydrite is found to be of only local occurrence. In New York and in Michigan the Salina formation contains both gypsum and salt deposits, but practically no anhydrite. In Manitoba, on the other hand, in an Upper Silurian formation which cannot be definitely correlated with the Salina of New York, but which is at any rate of approximately the same age, gypsum and anhydrite occur in the most intimate relationship.

The Speeton Clay of Yorkshire is of considerable interest, as it is the chief marine representative of the Lower Cretaceous formations in England. It has been the subject of important papers by Professor J. W. Judd, F.R.S., and Mr. G. W. Lamplugh, F.R.S., while the palæontology of the Cephalopoda and Lamellibranchiata has been respectively worked out by Professor A. P. Pavlow and Mr. H. Woods. Mr. C. G. Danford has also contributed to our knowledge of the beds. The Microzoa, however, have never been examined, and the present paper gives the results of an investigation of the Foraminifera of the deposit.

The geological importance of this boring lies in the fact that it is the deepest which has yet been made in the Bovey Basin, that the site is nearly in the middle of that basin, and that it is evidence of the great depth of the syncline or trough in which the Bovey deposits lie. Although it did not reach the base of these deposits it is highly desirable that we should know the exact depth to which it was carried, as it is the only means of estimating the minimum depth of the basin.

The fossils which form the subject of this notice were obtained from the slates exposed in the excavations for the foundations of the “Pengelly” Lecture Hall, which was added to the Museum of the Torquay Natural History Society in 1894. They were collected by Mr. W. J. Else, the late Curator of the Museum, and were examined by the late Rev. G. F. Whidborne, who published some account of them in the Geological Magazine for 1901, p. 533.

When Mr. Whidborne's paper was published I was not specially interested in the details of the geological structure of Torquay, but since then I have paid much attention to these local details and have collected fossils from all existing exposures. I was consequently surprised to find on reference to the note published by Mr. Whidborne that he had regarded these fossils as a Lower Devonian assemblage, in spite of the fact that the Museum is in close contiguity to a tract of Middle Devonian Limestone, as shown on the map of the Geological Survey published in 1898. Moreover, he quoted a statement made by the late Mr. A. Somervail regarding the stratigraphical position of the slates which is entirely incorrect. It is not true that in ascending the Torwood valley from The Strand one passes over a descending series of rocks. The beds underlying The Strand are shaly slates, which dip northward under limestone, and the same slates run up the valley to and a little beyond the Museum; they are then succeeded by limestone which crosses the valley in a south-east direction, and about 100 yards higher up this is faulted against slates which are believed to be of Lower Devonian age.

The controversy which has raged round the problem of the Eoliths seems little nearer a satisfactory solution than it was upon the publication of Sir Joseph Prestwich's papers of 1889, 1891, and 1892. The present article is an endeavour to place certain sceptical considerations before the readers of the Geological Magazine.

There are three exposures of the horizon of the zone of O. pilula on the Dorset coast—at Ballard Head, Arish Mell, and Middle Bottom. Dr. Rowe's description of the Ballard Head section is so unattractive, and the section itself so inconvenient for access and study, that I put it aside to be attempted only if I had time to spare after working out the others, which has not yet happened. Of the other two, that at (or rather under) Middle Bottom is so much the better that I take it first.

The recent discussion on the origin of the Himalaya, initiated by Colonel S. G. Burrard in his paper “On the Origin of the Himalaya Mountains”, has centred in the theories of isostasy and mountain compensation advocated by the Rev. O. Fisher and Mr. J. F. Hayford.

In his latest contribution to the subject Colonel Burrard states very clearly the problem of isostasy now requiring solution—

“Continents and mountains have been found to be compensated by underlying deficiencies of density; how has this condition resembling hydrostatic equilibrium arisen upon a solid globe of rock?”

In a recent paper I have advanced reasons for believing in the existence in the earth's crust at a certain depth, at present unknown, of a highly garnetiferous shell of rock, for which the name infra-plutonic zone or shell is suggested. This zone is situated at such a depth that pressure becomes a dominant factor in mineral transformations, the accompanying high temperature ensuring a sufficient degree of molecular mobility. It is suggested that under the influence of these high pressures (and temperatures) reactions will ensue between the various ferromagnesian silicates—micas, amphiboles, pyroxenes, olivines—and anorthite felspar, with the formation of garnet as a characteristic mineral: the reason assigned is that a reduction of volume accompanied by an absorption of heat is thereby effected, it being accepted that the garnet-forming reactions are endothermic.

If one can accept the philosophical necessity for the existence of this infra-plutonic shell, then some theory of isostasy seems logically to follow, with the garnetiferous plastic-solid shell as the cushion upon which the isostatic adjustments of the earth's crust have their foundation.

In the year 1911 Mr. Griffith and I proposed to recognize in Hants three divisions of the Chalk intervening between the zones of Marsupites testudinarius and Belemnitella mucronata, and then known as the zone of Actinocamax quadratus. These divisions we were not jointly prepared to treat as more than subzonal. In the year 1912 I defined the lower and middle divisions very closely and described them in detail, and demonstrated that the upper boundary of the middle division was a strongly marked break. This break I regarded as of zonal importance, and I therefore separated the lower and middle divisions from the upper as subzonal divisions of a new zone of Offaster pilula. I was also able to say that the features of the new zone in Hants were exactly reproduced in the Sussex cliffs and to cite as presumptive evidence that it was equally recognizable in Wiltshire a statement by Dr. Blackmore that the divisions proposed in 1911 held good round Salisbury. The object of this paper is to trace the new zone in detail in the more accessible cliff sections of the old zone of A. quadratus in the South of England.

The shell-bearing gravels of the county of Wexford have become so well known on account of their fossil contents that the boulder-clays associated with them have received scanty recognition. Very diverse statements have been made in regard to thè position of the gravels in the succession of superficial deposits, and they have, frequently been confused with the 'marl' which was extolled by early writers upon agriculture. Nearly all the references to the manurial value of such materials in Co. Wexford refer to this marl, that is, to a shelly and calcareous boulder-clay. The gravels, however, have been commonly styled 'manure gravels' by geologists, and R. J. Griffith, as far back as 1836, distinctly states that the shells are sometimes so very numerous “that the gravel is raised for manure”.

The rocks of this series form an interrupted belt along the southern border of the Highlands from Stonehaven on the east to the island of Arran on the west, and they appear again on a more extensive scale in Ireland. In Scotland the series consists of cherts or jaspers and shales, sometimes associated with limestones and with some peculiar igneous rocks. The age of the series has been for years a matter of controversy. Many geologists have held that these rocks are of pre-Cambrian age, but Messrs. Peach & Horne in their volume on The Silurian Rocks of Britain (Mem. Geol. Surv., 1899) remarked on the close resemblance of the rocks of this belt to some of the Arenig rocks in the Southern Uplands of Scotland, and the belt has been marked on the Geological Survey maps as doubtfully Lower Silurian.