In the September number of this Magazine Mr. T. O. Bosworth raises some questions with regard to the zoning of the Lower Chalk in general, and of Cambridgeshire in particular. As I am responsible for the subdivision of the Lower Chalk of this country into zones I suppose the matter concerns me more than anyone else.

The town of Yass, N.S.W., is situated on the Southern Railway about 190 miles from Sydney. It is the centre of one of the most picturesque districts to be met with on the journey from Sydney to Melbourne. The surrounding country is a veritable geological and palæontological paradise for the collector, who may depend upon turning up some new and interesting specimens every trip he takes to the district. The town itself is built on the Upper Silurian rocks, which about two miles distant, at a bend in the Yass River known as Hatton's Corner, offer to the palæontologist one of the most prolific collecting-grounds in Australia. Amongst the first to investigate these rocks were the Rev. W. B. Clarke and Mr. C. Jenkins, whose work was followed by a survey in 1882 by the Mines Department. Further good work was done by Mr. John Mitchell whilst stationed in the district; but even at this late hour there is a large amount of interesting work awaiting completion.

During the Spring meeting of the Yorkshire Geological Society at Pateley Bridge it was suggested that, as a first step towards the zonal classification of the Lower Carboniferous rocks of Yorkshire, it would be desirable to determine the horizon of the basement beds at Ingleton as compared with the Avon sequence. As the Yorkshire Naturalists Union had arranged a meeting at Ingleton for May 12–14th, the geological route was arranged so as to include as many exposures of the basement beds as possible. The result of the observations made then and during subsequent visits is the subject of this communication.

The Eleidæ are a very natural family of extinct Polyzoa, remarkable for exhibiting characters relative to both the groups Cyclostomata and Clieilostoraata. It is not, however, the affinities of this with other families that are here considered, but a means of determining by zoæcial characters the reptant ‘ species’ within the group; the validity of the ‘genera’ forming it; the occurrence in England of one of the ‘genera’—Semimultelea— hitherto unrecorded from Britain; the description of a new species of this ‘ genus’; and the phenomenon of local groups of zoæcia having characters differing from those of the rest of the zoarium.

Some time since Mr. John T. Stobbs, F.G.S., obtained a very well-preserved impression in clay ironstone of the wing of a Neuropterous insect from the rich plant-bed at Foley, near Longton, North Staffordshire, which he very obligingly submitted to me for study. The geological horizon is that of the “Peacock Marl” (i.e., the marl overlying the Peacock Coal), and it therefore comes from near the top of the workable Coal-measures.

The object of this paper is to suggest some modification of the present zoning of the Lower Chalk.

That silica appears as a constituent mineral of igneous rocks in two distinct phases, viz. quartz and tridymite, has been known for some time. The writer is not aware that any explanation has been offered which would indicate the conditions determining the appearance of one or the other in a cooling fused rock-mass. He now proposes to describe certain experiments made with a view to explain why it is that though the free silica generally appears as quartz, yet occasionally, as in certain trachytes, it crystallizes out as tridymite.

The last few years have inaugurated a new era in the history of the South African diamond deposits, inasmuch as rich bodies of diamantiferous ground have been located at great distances from localities which have previously been worked successfully. The group of which the Premier Mine is the best known member is the most striking example of this extension of area, but the centre of gravity of the diamond-mining industry seems to be gradually shifting northward, and the opening up of the interesting deposit of the Somabula Forest, so far north of any other known occurrence, foreshadows the development of an important branch of the industry in the Cinderella of the South African provinces, as Rhodesia has been not inaptly termed.

Professor Suess has somewhat recently stated his belief that the waters of all geysers and boiling ‘pulsating’ springs and of some mineral springs are of ‘hypogene’ or direct magmatic origin (Abstract Geog. Journ., vol. xx, p. 518). I am unfortunately unable in this backwater of science to verify the abstract by reference to the original (Gesell. Deutsch. Naturforscher und Aertze, 1902). With his belief, however, several prominent Continental and American geologists have expressed their concurrence, and some have indeed amplified the hypothesis to cover the origin of metalliferous deposits near igneous contacts. For example, W. H. Weed (Trans. Amer. Inst. M.E., vol. xxxiii, p. 746) says: —

Until recently very little attempt has been made to classify the reptilian fossils of the Karroo Beds according to their geological horizons. Seeley recognised certain zones—(1) the zone of Mesosaurs, (2) the zone of Pareiasaurs, (3) the zone of Dicynodonts, (4) the zone of specialised Theriodonts, and (5) the zone of Zanclodonts. While the order of these zones is correctly given they do not cover the whole period, and the third zone is an unnatural one.

Between Crotty's Lough and Coumshingaun a long spur of the Comeraghs juts out eastwards for about a mile and a half with an average height of 1400–1500 feet. On the south side this projecting ridge descends rather steeply to a stream at its base, which heads at a height of over 2,400 feet on the lofty plateau between Coumgorra and Coumshingaun; it runs down the mountain-side in a narrow gully over bare rock and reaches the foot in a series of picturesque waterfalls. No glacial débris occurs in this ravine, but on the lower ground the stream flows over the margin of the moraines belonging to Coumshingaun and runs eastward as the River Ire to join ultimately the Clodiagh.

Attention has lately been called by M. Marcellin Boule to the production in cement-mills in the Commune of Guerville, near Mantes, of all the more characteristic forms of Eoliths, and of these he has given photographic reproductions. The evidence for the necessarily artificial shaping of Eoliths had for many years been questioned by him, because he had found chipped flints of this character in the midst of Oligocene or Miocene beds in Auvergne and in the Velay; and it seemed imprudent to infer the existence of man in those early stages of the Tertiary period in the absence of osteological evidence.

In estimating the maximum load which pressed upon the northern type of Glacial (Dwyka) Conglomerate in Prieska, Cape Colony, I assumed that the calculations of Sir Wyville Thomson and Bernacci were correct, and that the greatest column of ice that could exist on the earth's surface was from 1,400 to 1,600 feet high. This limit, however, is by no means accepted by European glacialists, who, though they do not go as far as Dr. Croll in assuming thicknesses of 120,000 feet, yet see no reason why there could not have been ice-sheets 5,000 feet thick. The publication of Captain Scott's narrative of the voyage of the “Discovery” has given us certain definite data from the Antarctic which enable the case for the 1,600 feet maximum to be put with more confidence, and I will endeavour in the present paper to state the main lines of the argument. The question is of importance not only to us in South Africa with our two Palæozoic ice-ages, but to all geologists, as it affects the problem of the earth's equilibrium. To give a recent example, Professor Penck, in describing the Bodensee, discusses whether the weight of ice pouring down from the Alps in a sheet 3,600 feet thick may not have had some effect in producing a sinking in the earth's crust.

In view of the vigour with which the investigation of the English Chalk is at present being carried out by amateurs, resulting in the accumulation of large numbers of fossil specimens which give rise to difficulties of nomenclature, the publication of a key to aid collectors in determining the specific position of members of one of the largest Cretaceous genera of the phylum Polyzoa does not seem inappropriate.

Pendleton lies on the north-west side of Manchester and within the borough of Salford, and is traversed by the well-known Pendleton or Irwell Valley fault, a fault which has been traced for more than twenty miles from the neighbourhood of Bolton to that of Poynton in Cheshire. The fault is still slowly growing, for, on February 10th, 1889, a slip near Bolton gave rise to an earthquake of intensity 6, felt over an area of about 2,500 square miles. Small superficial movements may also be taking place close to Pendleton, though here probably aided by mining operations. Within the last seven years there have been local shakes on three occasions, namely, February 27th, 1899, April 7th, 1900, and November 25th, 1905. The materials for the study of the first two of these shakes are not quite sufficient to determine the boundaries of their disturbed areas with accuracy. The areas appear, however, to have been approximately circular in form and about four or five miles in diameter. In both cases the intensity of the shock was 4, or nearly 5. In 1899 the centre of the disturbed area was about half a mile north of Pendleton and a short distance on the north-east or downthrow side of the Pendleton fault; in 1900 it lay a mile or two farther to the south or south-south-east of the former centre.

Although many of the nodular bodies met with in sedimentary rocks which were formerly held to be concretions or simple aggregations of mineral matter have since been found to be due to the work of minute animals or plants, there is yet a more numerous class of true concretions which were undoubtedly formed by chemical reaction in the surrounding water and sediments; the resulting precipitation being often deposited upon nuclei of organic origin, as fish, woody fragments, or shells. Occasionally these nodules were of subsequent formation to the deposit in which they occur. In nodules which include organic remains, the segregation was accelerated by the partial decay of the included organic fragments.