Speculation as to the causes of the great intrusions known as batholiths is coeval with petrology as a science. Daly says that batholiths are “the least understood of all the intrusive bodies. If they were truly understood there would be no ‘problem’ of the igneous rocks”.1 This, no doubt, puts the matter too strongly, but there is nevertheless much truth in the statement, and the “problem” is of the greatest importance in petrogenic theory.

There are two specimens of Bellerophon in the collection which may be co-specific—one is fairly well preserved, though a little distorted, and the other is worn.

The Upper Gondwána (Rajmahál Series) beds near Madras are divided into two groups, the lower of which has been named from Sripermatúr, a town 25 miles west-south-west of Madras, and a well-known locality for fossil plants. The group is composed of white and pale buff-coloured shales containing plants, at least 10 feet in thickness, resting upon sandstones, grits, and micaceous sandy shales, at least 15 feet in thickness, whose base is not seen, but which probably rest on the gneiss. Silicified wood occurs in some of the gritty beds. The other fossils occur in the shales, and consist of plant and animal remains. The latter are poor, and comprise two or three indeterminable species of ammonites and several lamellibranch bivalves.

The forms which Mr. Davidson in his invaluable Monograph has included under T. ovoides, are so various that it would be possible to refer the shells figured in the plate to that species, but since T. trilineata, from the Inferior Oolite, and T. lata and T. ovoides, from drift-blocks—which I shall endeavour to show are of the very latest Jurassic horizon—are very different in many respects, I prefer to give a new name to this form, which may find its place near T. ovoides and T. simplex. The specimen drawn, Fig. 1 and la, is from the collection of Mr. Roper of Lowestoft, who obtained it, with another specimen, from a gravel-pit at Thorpe in Suffolk. It has the general simple form of T. ovoides, but is remarkable for its great size. The imperforate valve is flattened in the mesial line, whilst the perforate valve is deep and raised into a well-pronounced keel in the mesial line extending from the beak; the foramen is small. The specimen figured is longer than the other in Mr. Roper's collection, which has the shorter, squarer form of Fig. 2, resembling T. simplex. This fine Terebratula may be known as T. rex.

It has been claimed that the hinge of one of the two major recumbent folds of the S.W. Highlands is exposed near Ben Lui. In this paper it is claimed that the form of the outcrops permits the existence of this recumbent fold only if the fold-axis plunges towards the south-west. Evidence is given that the plunge is in fact towards the west, and on this basis a profile has been constructed to illustrate the observed geometrical relationships of the rocks.

A fenestrate bryozoan species recently collected from the Visean of County Fermanagh, Ireland, appears to correspond in all respects with Retepora nodulosa Phillips, from a similar horizon in Yorkshire. The last-named form was never satisfactorily defined or illustrated, the original type material is lost, and after being neglected for many years the name was declared a nomen dumium by Miller (1961). It is now recognized that, because of the presence of biserial carinal nodes, the species properly belongs in the genus Minilya, Crockford, 1944. It is here redescribed on the basis of a neotype from Fermanagh.

In the Geological Magazine for July, 1871, Plate VIII. pp. 289–294, I published an article on the above subject, giving my views of the appendages of Trilobites, and reproducing the figure of Asaphus platycephalus, Stokes, showing traces of eight pairs of locomotory appendages, discovered by Mr. Billings in the Trenton Limestone, city of Ottawa, and described and figured by him (in Quart. Journ. Geol. Soc. 1870, pp. 479–486, and plates xxxi. and xxxii.). I also appended a note to Mr. Billings's paper (op. cit. 1870, pp. 486–488) on a palpus of Asaphus from the same locality, which is as follows:—“Having been requested by Sir William Logan to examine the Trilobite sent over by Mr. Billings from Montreal, I was led to compare it with certain specimens in the British Museum collection, presented by Dr. J. J. Bigsby, F.R.S., some years since.

The true test of the classification adopted for European sedimentary formations is to endeavour to apply it in distant parts of the earth. It will then be seen whether the classification in question is real, or whether it is founded on local and accidental peculiarities of the rocks in a particular region.

Shells with the external aspect of Bouchardia have been known for some time from the New Zealand Tertiary (Oamaruian), and were first described by Hutton in 1905 under the names of Bouchardia rhizoida and B. tapirina. The correctness of this generic ascription was doubted by von Ihering, who stated that the shells lacked the characteristic external form of Bouchardia. In this, however, von Ihering was mistaken, probably owing to the unsatisfactory nature of Hutton's figures, for these species agree externally with Bouchardia in the very characters which he supposes they lack, viz., the very sharp beak ridges, the more or less straight sides, and the presence of a longitudinal cord over the suture of the deltidial plates. The most characteristic external feature of the shell of Bouchardia is that the sharp beak ridges unite in an apex dorsally of the foramen, i.e. the foramen is epithyrid. In Hutton's supposed Bouchardiæ the foramen is permesothyrid, but almost epithyrid.

Calcareous algae in limestones of the Permian Chihsia Formation near Nanjing, China, are preferentially replaced by quartz. Replacement postdates both cementation by sparry calcite and also neomorphic alteration of the original skeletons to sparry calcite. It is thus diagenetically relatively late. The original replacement silica could have been massive opal CT, opal CT lepispheres, or quartz. Lepisphere-like bodies occur in a few specimens. Megaquartz rims represent later overgrowths on the silicified skeletons. Although the original ultrastructure of the algal skeletons is not preserved, the preferential silicification allows fine details of the skeletal morphology of the algae to be observed and the distribution of silica indicates the style of replacement which has probably occurred. In some specimens it is possible that dissolution of the skeleton was followed by void-filling by silica, including the possibility of lepisphere formation. But in other cases in situ replacement, probably by massive opal CT or quartz, is reflected by the replacement of the outer parts of calcite crystals by silica. This process produces a network of silica, and as it proceeds the calcite centres of the grains become progressively smaller until silica replacement is complete. Sponge spicules may have provided the most important silica source for replacement. It is proposed that water-insoluble organic films surrounding matrix grains, and now preserved as bituminous material, protected the matrix from replacement thus promoting selective late diagenetic silicification of these fossils.

It has long been recognized that, in early Eocene times, while the “Calcaire de Mons” was being deposited in the Belgian area, large tracts of the Upper Chalk were removed by denudation from the south-east of England. The true extent of the unconformity between the Chalk and our oldest Eocene strata is now to be seen only where the Eocene cover yet remains. Even where the Chalk is so covered, the unconformity must have been accentuated to some extent in consequence of the solvent action of percolating carbonated waters, the evidence of which is familiar to us as “pipes” in the Chalk filled with Eocene strata, and the persistent bed of unworn, green-coated flints (“Bull-head” Bed) which everywhere occurs between our lowest Eocenes and the Chalk; but such secondary action is likely to have been more or less uniform throughout the whole area beneath the Tertiary cover.

The Christianburg and Akyma deposits afford excellent examples of the highly aluminous or bauxitic type of laterite formation. They here occur as parts of a residuary deposit derived from the decomposition in situ of an igneous rock, probably a porphyrite or a tuff, an almost pure quartz-sand, and masses of bauxite containing in the more aluminous varieties from 92·6 to 94·4 per cent. of the hydrates of alumina and in the ferruginous ones 64·6 per cent. of the hydrates of alumina with about 24 per cent. of the oxides and hydrates of iron.

It has not hitherto been clearly made out in what way these Carboniferous patches are related to each other. Some have considered it doubtful whether the three former are in any way represented in the Coalbrook-dale Field. The prevailing impression is, I believe, that the Clee Hill Fields are quite distinct in point of age from any of the Coal tracts surrounding them, and were formed in a depression sufficiently low to receive the Millstone Grit which we find to be wanting in the extensive Coal-fields to the East and North-east, except, let me observe, along the Western margin of the Coalbrook-dale district, where it is not well developed, but still represented. Eastward of that margin, however, it thins out rapidly, and gives way to the Silurian flooring of that Coal-field.

Dolomite is common in parts of the Chalk Group of North Sea petroleum reservoirs. The stratigraphic distribution, microtextures, and stable isotope ratios of dolomite vary both within and between four of the North Sea chalk fields examined in this study, the Eldfisk and Tor of the Norwegian Sector, the Dan Field of the Danish Sector, and the Machar Field of the United Kingdom Sector, indicating that the conditions favourable for dolomitization occurred at different times and places in the North Sea Central Graben. Dolomitization in all of the examined fields occurred late during diagenesis, after significant compactional grain breakage. Dolomite precipitation in the Eldfisk, Dan, and Machar fields occurred in modified sea water, which had Σ18O values between the assumed Cretaceous/Tertiary seawater value −1 and +8‰ (SMOW). The enrichment in 18O was probably the product of calcite recrystallization at elevated temperatures in a low water/rock ratio system. The timing of dolomitization varied with respect to organic diagenesis; dolomite precipitation in the Eldfisk Field coincided with bacterial methanogenesis whereas dolomite precipitation in the Machar Field probably coincided with bacterial sulphate reduction. The magnesium in the dolomite may have been derived from the neomorphism of high magnesium calcite to low magnesium calcite.

So far as the writer is aware, no sodic or “contaminated” rocks have been recorded from Iceland, and it was thought that an examination of some black sand collected by Dr. L. Hawkes, and kindly supplied by him, might reveal the presence of minerals from such rocks.

The geological succession of the rocks of the N’Changa District is so typical of that of the Northern Rhodesia Copper Belt as a whole, and indeed of much of the Colony of Northern Rhodesia, that it is felt that a summary of the sequence of events which together make up the geological history of the district may serve as a contribution to the geological literature of the general Northern Rhodesian field. For a fuller account of the details of the petrography and mineragraphy of the rocks and ores of the N’Changa District reference should be made to Bancroft and Pelletier (1929), and Jackson (1932).

About ten years ago, when studying the drifts of East Yorkshire, Mr. G. W. Lamplugh counted and roughly classified the larger boulders of Flamborough Head and other selected localities on the coast. This work has been continued by members of the Hull Geological Society, who have up to the present time recorded nearly four thousand boulders, of twelve inches and upwards in diameter. To avoid possible error, arising from the moving beach and other causes, only the boulders actually in place in the clay were noted, or such as had obviously recently fallen from the cliffs. The whole of the coastline from Spurn to Flamborough has been surveyed in this way, and also portions of the coast north of Flamborough as far as Saltburn. The lists thus prepared have been published from time to time by the Hull Geological Society and by the Erratic Blocks Committee of the British Association.

The very uniform trend of all these ridges will have been noted, but my previous remarks on the general strike of the foreshore chalk require considerable modification. The whole of the chalk so far exposed may be divided into four sections. Each of these comprises an exposure in or close to the cliff of what appears to be the highest part of a ridge running down the beach in a direction from 10° to 30° south of east (and sinking as it goes) to about the half-tide level. Here three of them (the exception being the brickfield chalk) turn and run for some way roughly parallel to the shoreline, and then resume their original direction and run out to sea. The brickfield chalk only varies from this plan by running out to sea with practically no change of direction on the way. Except where a ridge is running up to the cliff, the substratum of the beach is invariably glacial clay down to about half-tide level. Here it is either banked against what appear to be vertical faces of chalk or else (between the foreshore exposures.) disappears under the sand. It has never been seen to run out to sea, and every time a fresh bit of the foreshore below the half-tide level is cleared of sand it is chalk that is revealed. In the case of the section attached to the north bluff there is below the half-tide level a continuous mass of chalk with perfectly regular bedding exposed for at least 1,000 yards along the shore, and directly opposite the north bluff I have myself seen chalk continuous from the foot of the bluff for over 200 yards straight out to sea (except about 20 yards close up to the bluff, which, however, are covered by Mr. B. B. Woodward's letter in the October (1905) number of the GeologicalMagazine), the regular sequence of the beds being only broken by one fault. The section attached to the ridge coated with a sheet of flint is a good second in size, showing chalk in regular sequence for a length of over 400 yards, and maximum (exposed) breadth of about 45 yards.

We here propose a new kinematic picture of central Sicily based on the results of detailed field mapping of the region, combined with structural analyses and the interpretation of the available literature subsurface data. Our study focused on the tectonic boundary of a structural depression, the Caltanissetta Trough, which is now filled with allochthonous terrains resting on the deep-seated inverted African palaeomargin units. Our data refer to the tectonosedimentary evolution of the thrust-top basins, from Late Tortonian to Quaternary times. The study points out the occurrence of regional E–W-oriented dextral shear zones, cutting the NE-oriented trends of the thrust belt. This new evidence would confirm the major role of the E–W trend in the tectonic inversion of the external portions of the Africa palaeomargin in Sicily. Our results could contribute to a better understanding of the location in Sicily of the tectonic lineaments accommodating the hundreds of kilometres of lateral displacement, caused by the Late Miocene–Quaternary Tyrrhenian Basin opening to the north of the island.