THE leading problems presented by igneous rocks are:—

(a) the nature and sources of the primary magmas;

(b) the mechanics of magmatic intrusion and emplacement; and

(c) the processes which have brought about the manifold diversity of igneous rock-types.

A RECENT communication from Mr. E.H. Davison relating to the possible age of the “ Lundy Island granite ” is interesting as affording several points of contrast with the results of detailed researches in structural and petrological characters of this some-what inaccessible island in the Bristol Channel, which the author has been carrying out for some time.

THE problem of the formation of the larger masses of granite is receiving considerable attention by geologists at the present time, and it is hoped that the following observations and surmises regarding the granites of Southern Rhodesia may be of more than local interest. Southern Rhodesia forms part of a typical Pre-Cambrian shield and consists, apart from younger formations, of about 74,000 square miles of granite and gneiss intrusive into 13,000 square miles of older rocks. The area has undergone tremendous denudation, which took place mainly during the Pre-Cambrian, and the structures exposed, therefore, are different from those seen in regions where only the peaks of granite masses have been uncovered.

At the outset I wish to thank Mr. H. B. Maufe for permission to draw from the store of information, much of it unpublished, which he has collected in the Geological Survey Office at Salisbury, and also for having the accompanying illustrations drawn in the office. This information includes both petrological and structural data, but it is only the structural aspect of the problem which it is intended to discuss here.

THE present paper gives a general account of the larger foraminifera from the Santa Elena Peninsula in south-west Ecuador, with descriptions of three new species. All the material except that from the Guayaquil Limestone was obtained from the concessions of the Anglo-Ecuadorian Oilfields, Limited, to whom my thanks are due for permission to publish these results.

IN his interesting paper entitled “ The Petrography of the Hunstanton Red Rock”1 Dr. R. H. Rastall arrived at conclusions regarding the relation of the Red Rock to the strata below and above it which are strikingly at variance with the result of our own examination of the series exposed in the well-known cliffsection at Hunstanton.2 While we considered that the Red Rock has no connection with the underlying Carstone, though resting on it with apparent conformity, and that the junction between these contrasted, beds marks a stratigraphical gap of great magnitude, we found no reason to recognize a break between the top of the Red Rock and the overlying Chalk. Dr. Rastall, on the other hand, impressed by the fact that there is a certain gradation and an appearance of conformability between the Carstone and the Red Rock, took this as showing continuity between these deposits; while the appearance of a physical break at the top of the Red Rock seemed to him to contradict our view that the top bed of the Red Rock and the Chalk above (“ Sponge Bed ”) are inseparable geologically.

AN interesting collection of Tertiary fossils has recently been sent me for determination by Mr. C. P. Manglis, Manager of the Mitsero mines in Cyprus, who has collected them from the neighbourhood of these mines. Mitsero village stands near the head of a valley running down the north side of the Troodos mountains to the plains of Morphou and is described by Messrs. Cullis and Edge (1, p. 38) as standing on volcanic rocks close to the junction of the pillow-lavas with the overlying marls and limestones, while “ behind it is a bold sedimentary escarpment breached by the valley just mentioned and culminating in Koroni Mountain (2,140 feet), 1½ miles to the westnorth-west ”. The Koronia Limestone, the outcrop of which on the Evrykou road the author visited in 1929 (2, p. 443), occupies the top of the escarpment, as shown on a map sent to me by Mr. Manglis of the immediate district (scale, 1: 10,000) from the village of Kato Moni on the north-west to the village of Mitsero on the south-east. The position and age of the Koronia Limestone have been uncertain owing to the lack of definite fossil evidence, though the author (2a, p. 251) was inclined to put it in the Miocene rather than the Pliocene on the strength of a species of Cerithium which he discovered in it. The majority of the fossils in Mr. Manglis’s collection come from this limestone and provide ample evidence of its Miocene age.

THE Carlingford-Barnave district falls within the boundaries of Sheet 71 of the Ordnance Survey of Ireland, and forms part of a broad promontory lying between Carlingford Lough on the north-east and Dundalk Bay on the south-west. The greater part of this promontory is made up of an igneous complex of Tertiary age which has invaded the Silurian slates and quartzites and the Carboniferous Limestone Series. This complex has not yet been investigated in detail, but for the purposes of the present paper certain references to it are necessary, and these are made below. The prevalence of hybrid-relations and contamination-effects between the basic and acid igneous rocks of the region is a very marked feature, and because of this it has been difficult at times to decide which types have been responsible for the various stages of the metamorphism.

AS it is unlikely that we shall have an opportunity of collaborating in further work on the Pleistocene deposits of the Cambridge area, we wish to add some short notes to our earlier work.

THE late Dr. Vaughan, in 1905, established the age of the sand-stone lying above the Whitehead Limestone of the Forest of Dean as of upper Seminula age, and not, as had been supposed, as the equivalent of the Millstone Grit. Later, in 1912, Dr. T. F. Sibly described the sandstone as “ composed very largely of pure quartz sandstones, often coarse-grained and friable. Conspicuous bands of quartz conglomerate occur: some clays and shales are intercalated, with the sandstones: and some haematite deposits are developed ”. The same author described the structure of the Forest of Dean coalfield and noted the perfectconformity of the Dry brook Sandstone on the Whitehead Limestone and the overstep of theCoal-measures. The latest description of the sandstone, and the one which is most complete, is given by Dr. Sibly in his work on the ironstone of the Forest of Dean. His description reads “ Red, white, and mottled red and white sandstones compose the bulk of the formation. The rocks are mainly friable, but compact and even quartzitic rocks occur. In the north-east seams of quartz conglomerate are numerous. In the south-west bands of gritty limestone and dolomite develop ”.

IN the January number of this Magazine there appeared a rejoinder by Messrs. Kitchin and Pringle to observations published by myself on their reading of the stratigraphical position of the Hunstanton Red Rock and its relation to the beds above and below. Since the following is intended as an answer to this, it is almost inevitable that it should be written in the first person. For this unavoidable egotism apologies are offered to readers.

HAVING already published a brief description of the accessory minerals of the granite in the neighbourhood of Dublin (1928) it had been the writer’s intention to make a study of the whole of the Leinster Granite giving special attention to the accessory minerals. As circumstances prevent the completion of this plan the following account has been drawn up, describing work done upon an area which extends from Dublin Bay to the neighbourhood of Aghavannagh, a distance of about 30 miles (compared with a range of 12 miles in the original paper) or nearly half the total length of the intrusion.

THE study of recent sediments has yielded important data bearing on the extent and conditions of deposition in ancient seas, but the collection of similar data relating to the ancient continents is more difficult. However, one may find in marine deposits some indirect evidence of the constitution of the neighbouring continents. The effect of the proximity of deserts on the composition of recent marine deposits does not appear to have been studied. With a view to collecting data bearing on this particular point, I have made an examination of the deposits of the Red Sea.

THE published amount of precise geological information concerning the relatively recent volcanic islands in the southern part of the Red Sea is remarkably small, being restricted, to the writer’s knowledge, to a single paper on Perim Island (1); even in this case the visit and the collection of specimens were made by one who was apparently not a geologist.

DURING the International Excursion for the study of the Pre-Cambrian held in Finland, July-August, 1931, a visit was paid to the outcrop of Bothnian conglomerates near Jaakkola, Suodenniemi, west of Tammerfors (Tampere). The excursion to Jaakkola was led by Professor Sederholm and Mr. Mikkola.

IN recent years great progress has been made in the correlations of the Glacial deposits with the culture stages of the Palaeolithic period. In particular the recent papers of Professor P. G. H. Boswell (1) and Dr. K. S. Sandford (15), whilst adding considerably to our knowledge, have at the same time brought out the inherent difficulties that arise in any attempt to correlate the culture stages with the sequence of glaciations.

THE geological formation in the district around the ancient village of Worth Matravers (Geological Survey Map, “ Swanage,” Sheet 343), situated about ¾ mile from the Dorset coast, consists of Lower and Middle Purbeck Beds (Upper Jurassic). A considerable portion of these beds has been removed by denudation, with the result that the Upper Purbeck division has not been preserved near the coast, except westward at Worbarrow Bay and Lulworth Cove, and eastward at Swanage, the exposures at these localities being due to the high northerly dip. The Portland Stone immediately underlying the Purbeck Beds forms a line of inaccessible sea-cliffs extending from Winspit, one mile south-south-east from Worth Matravers, to Durlston Head, 4¼ miles in a direct line eastward.

THE finding of a small pebble of fine-grained quartz-dolerite in an exposure of the Upper Brockram in George Gill, near Appleby, by Professor Arthur Holmes in 1925 and its identification with the rock of the Whin Sill led to the direct establishment of the timeof injection of the Whin Sill and related dykes as post-Carboniferous and pre-Upper Brockram (1928, pp. 532–4). Since 1925 parties of students from the Durham Colleges’ Department of Geology have made each year a careful search for similar pebbles not only in the George Gill exposures but in a number of others in the Brackenber Moor neighbourhood. These efforts have not been rewarded with any success until the present year, when a party under my guidance made a thorough examination of the George Gill Brockram and Mr. A. R. Leathley, of Hatfield College, had the good fortune to hammer out a pebble of doleritic aspect.

IN the course of a general survey of the Glacial deposits of East Anglia it has been found necessary to investigate the mineral content of a large number of samples of the well-known “Chalky Boulder-clay” over a considerable area of Norfolk and Suffolk.