The following article originally appeared in the Times Trade Supplement of August 28 last. It is here reprinted with some small additions by the courtesy of the proprietors of that Journal.

AMONG the Echinoids from the Limestone Lenticles of Shenley Hill (Leighton Buzzard), sent to me from the Sedgwick Museum, Cambridge (see Geol. Mag., Vol. LVIII, 1921, p. 57), one specimen of the many Pyriniform examples at once attracted attention by its preservation, relatively large size, and superficial resemblance to Holectypus. A brief comment on the specimen (No. 3 of the series) was made in the note already cited; further and more detailed examination, preceded by removal of matrix, has revealed additional features of much interest. Though averse to diagnosis of new genera or species based on single specimens, I have felt compelled to adopt that course in this case, in default of acquaintance with any described types to which the Shenley Echinoid could be assimilated. It is quite likely that other specimens, congeneric if not conspecific, may exist in collections; according to their preservation or the idiosyncrasy of individuals they may be labelled Holectypus, Conulus, or Pyrina with equal probability. It is even possible that some of the numerous species of Pyrina (including Pseudopyrina and Globator), already described, may be referable to the genus here introduced; but more details of morphology than are often supplied in systematic diagnoses and figures are needed before order can come out of the chaotic series of Cretaceous Echinonëidæ.

The tooth, of which a photograph (half-size) is reproduced, was found during Easter, 1916, by the late Mr. W. Harrison, of Selly Oak, Birmingham, who kindly lent it to the writer. Though similar finds are fairly common, this tooth by its form is of rather special interest, and so the writer thinks merits description.

THE origin of chert has of late been discussed with renewed activity, especially in American scientific journals. Difference of opinion centres mainly round the question of the source of the silica; whether it is of direct inorganic origin, or the result of the solution and redeposition of organic silica. Further points at issue relate to the age and formation of the chert; whether it is an original deposit contemporaneous with the country rock, or a metasomatic replacement of the latter and therefore of later age.

1. Thirty-six species of Foraminifera are recorded from various localities in the Hartwell Clay and associated beds. 2. The assemblage of species is characterized by:— (a) the abundance of rotulate Cristellarians of Lower Cretaceous type, and of Cristellaria fragraria. (b) the common occurrence of Vaginulina harpa, a Jurassic type. (c) the rarity of arenaceous, and the absence of porcellanous forms. 3. The Foraminifera from the Hartwell Clay are compared with those from other deposits in the Aylesbury district, and with those from foreign deposits of similar age. 4. The relative abundance of glauconite is a point of similarity between the Hartwell Clay and beds hitherto regarded as Kimmeridge Clay.

IN the course of a journey from El Obeid to Jebel Marra, in Darfur, Captain Hubert Lynes collected a number of the rocks from the volcano of Dereiba and from various other points on the route, shown in the map (Fig. 1). The rocks of this area have not been described hitherto. The following notes give a brief description of the nature of the country, with petrological details of the rocks collected.

THE features of the Glacial deposits and associated phenomena just discussed are in general so clear that most observers would arrive at the same conclusion regarding them, but there are some other features about which, either due to their controversial nature or the conflicting character of the evidence, there is not yet such general agreement. These are (a) the evidence for interglacial Periods in the Drift of these counties, (b) the raised beaches of East Durham, (c) the origin of the leafy clays, (d) the explanation of the distribution of fragments of certain rocks —Flint, Chalk, Magnesian Limestone—in the Superficial Deposits.

Black and white shading is frequently employed in geological maps and sketches, but there is a remarkable absence of uniformity in the means by which different strata have been represented.

In the most westerly working of Peldar Tor Quarry, in the northwest district of Charnwood Forest, a basic dyke is intruded into the porphyroid. Professor T. G. Bonney1 briefly described the dyke in 1915. The intrusion shows a remarkable laminated margin, and the present paper is chiefly directed to a consideration of this feature.

CAPPING many of the hill-tops of the Buchan district of Aberdeenshire there are extensive spreads of gravel containing pebbles of white quartzite and of flint. Their north-western limit is on the Delgaty estate, near Turrifi, where, at an elevation of 350–400 feet, there is a small patch of quartzite gravel a mile and a half to the north-east of the town. Nearly eight miles to the south, on Windyhills, two miles north-east of Fyvie, a more extensive outlier occurs. These two patches are shown in Fig. 1. The Windyhills spread is nearly a square mile in area, and it occupies the summit of a low flat-topped ridgo at an elevation of 370–400 feet. Like the Delgaty gravels, it is evidently the remains of a deposit formerly much more extensive and reduced greatly in area by denudation. It consists mainly of white quartzite pebbles, flint pebbles, and white clayey sand, and its resemblance to the Delgaty gravels is so close that no doubt has been entertained that they belong to the same period and formation.

During the last two and a half years I have been engaged in the study of the Cornish Veinstones in the field and in the laboratory by microscopic and other methods, and have come to the following conclusions:—

The following paper is an attempt to contribute to the solution of the problem of mountain building. It is here suggested that the folding of mountain ranges may be produced by the frictional drag of moving portions of the asthenosphere, and that these movements may be convective and result from its unequal heating by radio-active elements.

IMMEDIATELY east of Bloxham Station is a cutting through the Marlstone and basement beds of the Upper Lias. The Liassic deposits are now for the most part hidden by vegetation, but when the line was made and for some years subsequently large numbers of fossils—principally ammonites—were collected from them. Several geologists have published particulars concerning the section. The writer has in his collection a number of ammonites from here, which have been examined by Dr. A. E. Trueman. The object of this communication is to place on record the result of his examination.

A Small stream forms the boundary between the Parishes of Wensley and Winster, on the north-west of the former; and here abouts its bed, in the Limestone Shalc; is probably about 30 feet above the Carboniferous limestone. On the Winster side, the shales form a oded slope (Whites Wood) rising 100 feet in about 200 feet, and on this side the shale is quite normal and of the black colour usual in the lower beds of this formation. On the Wensley side the ground rises more gradually, and the actual bank of the stream averages not more than about 10 feet in height. Here, an altered shale is exposed and can be traced (through the activity of moles) in the fields behind.

1. Garnet gneisses of sedimentary origin are described from the oldest group of sediments recognized in Southern Eyre Peninsula, South Australia. The high-grade metamorphism which these rocks have undergone has resulted in the development of felspar, garnet (almandine), sillimanite, and green spinel. 2. The mineralogical association of these constituents is described, and their genetic relations are discussed. 3. A sedimentary origin of these gneisses is attested by their interbanding with undoubted sediments, their mineralogical composition, and lastly by chemical analysis. 4. In the garnet gneisses developed in the Grenville series of North America, notably those of the Adirondack region, and in the province of Quebec, these para-gneisses find their most striking analogues.

THE unique type-specimen of Hylonomus wildi, a small amphibian from the marine roof of the Mountain Four-feet Mine of the Lower Coal-measures at Trawden, near Colne, Lancashire, is now in the Manchester Museum, No. W 1222.

Occurrence of the Oil.—The oilfield of Jaba and those of Rawalpindi and Fatehjang are identical from the stratigraphical point of view. At Jaba, too, the oil is to be found in the contact zone between the Nummulitic limestone and the younger gypsiferous clays of the Upper Nummulitic. These gypsiferous clays represent a bed well adapted to favour the accumulation of oil, wherever they cover the limestone at a moderate inclination. The oil issues only from the limestone, but the cellular limestone, too, may be oil-bearing in depth. It may be pointed out that cellular limestones of the same character accompany the oil-shows at Gunda, the main oil-spring in the neighbourhood of Fatehjang.