It seems to be curiously difficult to obtain fair treatment for the theory of a continuously cooling earth and its consequence, the thermal contraction theory of mountain formation. After Davison and Darwin had calculated the available compression of the earth's crust on Kelvin's theory of the cooling of the earth, and obtained a result that was at any rate of an order of magnitude consistent with the observations then available, Osmond Fisher made a revised comparison, which amounted to supposing the mountains formed by compression all powdered and spread out uniformly over the whole surface of the earth; the thickness of the resulting layer was naturally very much less than the actual height of known mountains. So far as I have been able to trace, nobody protested against the assumption that the thickness of the material after it had been redistributed in this way was directly comparable with the height of the mountains as actually distributed, and Osmond Fisher's view seems to have been universally quoted as the last word on the subject. Even long after my rediscussion of the whole question in 1916, making allowances for the additional data provided by radioactivity, had again led to a result agreeing with observation within the uncertainty of the data, it was almost completely neglected in the literature of the subject, while Osmond Fisher's work retained undisputed pre-eminence.

The purpose of this note is to place on record the occurrence of the soda-bearing amphibole, riebeckite, in a particular type of dyke-rock in the Shetland Islands. To explain its field-relations a brief sketch of the general geology of the group is necessary.

The sand described in the following notes was dredged from the mid-channel of the river at the following places:—Swale Nab, Dunsforth, Aldwark Bridge, below Linton Lock, and Beningbrough. Two samples were also obtained from the Nidd at points 100 and 200 yards respectively from its confluence with the Ouse. For comparative purposes sand from the banks and alluvial flat of the Swale above Ainderby Steeple is likewise included.

Some of us are old enough for our geological infancy to have been nourished on books which were written at a time when the “Silurian System” was threatening to annex the whole of the Lower Palaeozoic Rocks. Most of us welcomed Lapworth's arrangement, which now seems to have won general approbation. In the interim, however, the following compromises were proposed:

Neither of them has been widely adopted. It is to be noted that De Lapparent's proposal of “Gotlandian” was made because he had already made use of “Silurian” as an inclusive designation. His selection of the term was of course founded upon the fact that the beds in question are finely developed in Gothland.

The Geological Survey has recently formed a very extensive collection of the dyke-rocks of Galloway. This collection was made mainly by Mr. Robert Eckford, and, to a less extent, by Mr. Wm. Manson. One or more specimens were taken of practically every dyke shown on the original 6-inch field-maps. Since there are over 500 collected dykes in Wigtownshire alone, the size and importance of this collection is apparent. A dyke-suite of this magnitude, so thoroughly collected without the personal bias of the petrographer, supplies unique material for study. By the kindness of Sir John S. Flett, F.R.S., Director of H.M. Geological Survey, I have been permitted to investigate that part of the collection coming from Wigtownshire. This Wigtownshire portion consists of considerably over 1,000 rock-specimens, nearly 200 of which have been sliced. In this present paper I propose to give an account of the distribution and petrography of one group—the mica-lamprophyres—of the Wigtownshire dyke-rocks.

Professor Gregory, in a very interesting paper published in the Transactions of the Faraday Society, has advanced various arguments against the theory of the magmatic origin of the Sudbury nickel deposits and has quoted several authorities as opposing that theory. His brief account of the subject presents, unintentionally of course, only one side of the controversy in regard to those ores, and lest the deservedly great authority of his opinion should seem to settle the question, I wish to place before English geologists an outline of the arguments on the other side.

In April, 1925, while mapping the coastal plain of the Red Sea south of Berenice for the Egyptian Government, I came across a remarkable example of columnar structure in sandstone, an illustration of which is shown in the accompanying photograph.

During the summer of 1918 a party under the direction of Mr. Hamlin Brooks Hatch carried on field studies in a section of the property of the Reid-Newfoundland Company in Western Newfoundland. A number of features of general scientific interest were noted, among which was faulting of the Appalachian type. The writer is indebted to Mr. Hatch for permission to publish this phase of the results of the latter's investigations.

Ammonites are comparatively common in the Cenomanian or Lower Chalk, become rarer in the Turonian or Middle Chalk, and are very scarce in the Upper Chalk. On a former occasion, when pointing out that while ammonites were unknown from the Micraster cor-testudinarium Chalk of England, they occurred in the same Chalk in the north of France, the writer was inclined to attribute this absence or scarcity to limited horizontal distribution of the ammonites. The possibility, however, of there being gaps in the Chalk succession, for example at the horizon of Actinocamax plena, at the Chalk-Rock, in and above the cor-anguinum zone, etc., cannot be denied. The zone of Micraster cor-anguinum is not quite so barren as the zone below, but the only ammonites hitherto known from it are doubtful examples, probably referable to Parapuzosia. One impression, on an oyster, of part of the ventral area of a large specimen, possibly of P. corbarica Grossouvre sp., was collected by Mr. Dibley in the London-Portland Pit at Northfleet, Kent, and Dr. Rowe recorded probably comparable Parapuzosia (“ammonites of the leptophyllus group”) from Dorset and Yorkshire.

The following article includes a description of the larger Foraminifera of the Upper Ranikot Series of Sind in Western India. The specimens examined consist of a collection made by Mr. D. Dale Condit and by myself in the winter of 1923, as well as material kindly loaned by the Indian Geological Survey. I wish to thank the directors of the Whitehall Petroleum Corporation for permitting me to make use of the specimens collected during a geological reconnaissance undertaken on their behalf. Of the specimens figured those loaned by the Survey have been returned to Calcutta, and the remainder placed in the Sedgwick Museum, Cambridge.