The South Qinling block, a segment of the Yangtze craton involved in the Qinling–Dabie orogen, is critical for understanding the tectonic evolution of eastern China. However, the tectonic setting of the South Qinling block and the northern margin of the Yangtze block during middle Neoproterozoic time has long been the subject of debate, with two distinctly different models (continental rift or volcanic arc) proposed. Here, a comprehensive study of zircon U–Pb geochronology and geochemistry has been carried out on the Chengwan granitic pluton from the Suizao terrane in the South Qinling block. The granites are monzogranite and syenogranite in lithology, and are mainly composed of potash feldspar, quartz, plagioclase and biotite. This suite has long been regarded as a Palaeozoic magmatic pluton, but zircon U–Pb ages of 809 ± 9 Ma and 816 ± 4 Ma are obtained in this study. The granites are metaluminous to strongly peraluminous with high alkali contents, and exhibit highly fractionated features, including high SiO2, low Zr/Hf ratios, rare earth element tetrad effects and enrichment of K and Rb. They show Hf–Nd isotopic decoupling, which may be genetically related to their petrogenetic process. Based on the geochemical features and the positive εHf(t) values of the zircons, it is indicated that the granites may have been derived from partial melting of juvenile tonalitic rocks by biotite breakdown under fluid-absent conditions. The Chengwan granite geochemically belongs to the A2-subtype granites, suggesting that it might have formed in a post-orogenic tectonic setting. The highly fractionated A-type granite in this study may represent extensional collapse shortly after the collisional events in the South Qinling block, and thus indicate a tectonic regime switch, from compression to extension, as early as middle Neoproterozoic time. Integrating our new data with documented magmatic, metamorphic and sedimentary events during middle Neoproterozoic time in the region may support a continental rift model, and argues against arc models.

The mid-Oligocene sediments forming the Beacon Cottage Farm Outlier at St Agnes, Cornwall, have a stratigraphical and geomorphological importance which is out of all proportion to their modest residual bulk (some 300000 m3). During 1986–8 61 holes were sunk into the area surrounding Beacon Cottage Farm; many penetrated the Palaeozoic floor beneath the outlier. Collectively, these show that the outlier mostly covers rotten granite and Killas. The sub-Oligocene unconformity is uneven and varies in altitude by at least 20 m. The local Bovey Formation succession comprises two members: Basal Sand, which is often pebbly, and sandy silts, known commercially as Candle Clay, the whole totalling a maximum of 8.9 m. There is indirect evidence either that slopes on the rotted Palaeozoic floor locally exceed 45° or that several post-mid-Oligocene faults affect the outlier. We conclude that the Beacon Cottage Farm sediments probably represent aeolian, colluvially and fluvially redistributed rotten rock residues, formed locally during a break in the long period of late-Palaeogene subtropical weathering and pediplanation. The outlier is considered in relation to the geomorphological evolution of the Cornubian Massif.

The determination of the stability conditions of chlorite, especially the stability temperature between 500° and 700° C. by B. W. Nelson, D. M. Roy, R. Roy, and H. S. Yoder complements the conclusions arrived at from the microscopical study of the interstitial chlorite in the diabase-minverite series of south-west England. These disprove the assumption that the chlorite generally originates from metasomatic reaction or devitrification of a glassy residue. Considering the formation of chlorite at a late stage of solidification, an explanation of its genesis is attempted on that basis. Possible effects on the petrologic evolution are discussed.

The chlorite taking part in the filling of amygdales and pseudoamygdales has formed preferentially by replacement of carbonates. Variation in form, degree, and associated products is exemplified. The appearance of a liquid carbonate phase, ascertained by P. J. Wyllie, O. F. Tuttle, and R. I. Harker in the system calcitewollastonite-water at temperatures between 640° and 680° C. seems to be realized likewise under natural conditions, and to provide a basis for the understanding of certain phenomena, especially in reaction zones.

Except in containing small nodules of phosphate of lime, the Chalk shows no structural change where it terminates in the Ely section, but passes down almost imperceptibly into a dark greenish layer, and rests on it at an angle of about 35°. This greenish band, scarcely a foot thick, is full of nodules of phosphate of lime, and consists largely of glauconite. It is the Upper Green-sand, with Ammonites auritus, Terebratula biplicata, Dentalium ellipticum, and the usual local features. Nowhere can the passage of one rock into another be more marked than that of the Upper Greensand of this district into the Chalk. Conditions have changed a little with physical geography, but nothing suggests any break in time. About Cambridge the section is exactly the same; the Chalk just above is often flaggy, contains a few green grains, a little phosphate of lime, and the commoner Greensand fossils mixed with those of the Chalk. Sometimes, however, there are some 10 or 12 feet of dark greyish-green marls above the Upper Greensand. They are separated by sharp lines of bedding from the Chalk, are very local, and perhaps only indicate a trifling denudation of the Gault.

The following account of the genus Syringothyris is the result of work undertaken at the suggestion of Professor T. F. Sibly, and is intended as a preliminary to a revision of the British species of that genus, which I hope to present at some future date.

Twenty-One years ago Dr. Flett in a valuable paper (Trans. Edin. Geol. Soc, vol. vii, 1897) described an exceedingly beautiful hypersthene andesite from the volcanic series of the Lower Old Red Sandstone at Dumyat in the Western Ochils. In the following brief communication I propose to give a short petrographic account of a strikingly similar rock that has occurred to me in the field in a more easterly portion of the same range of hills and which is of the same geological age.

The Ballachulish “ granite ” has been well known to petrologists for many years through the writings of Sir J. J. H. Teall, while more recently Mr. E. B. Bailey has described both the igneous rock and its associated contact phenomena in the Geological Survey Memoir for Sheet 53 (Scotland).

Lough neagh is one of the numerous lakes possessing a few species, either identical with or differing but slightly from true marine forms living in the present seas. The idiots of Lough Neagh are the pollan, Coregonus pollan, and the shrimp, Mysis relicta (a near relative of the marine Mysis oculata). They have been described by Dr. R., F. Scharff and Professor W. Dakin and Miss M. Latarchie.

In the course of investigations amongst the Microzoa from the Gault of Copt Point, Folkestone, some Forarainifera came under my notice, which are hyaline representatives of the usually arenaceous type Webbina. These forms are remarkably similar in external appearance to those of the arenaceous group, but microscopical examination of the test under a high power reveals the finely tubulated structure characteristic of the hyaline type.

As in the previous notes (Geol. Mag. Decade II. Vol. VII. No. 10, p. 447, 1880), so in the present, it is deemed desirable to give in the first instance a complete list of all the examples of the groups under consideration, which have hitherto been recorded, and then, having examined each critically, finally to give a corrected list.

During the early part of 1899 extensive excavations were made on the south side of Tooley Street, Bermondsey: just east of Shand Street, and on the site of Nos. 156–164, Tooley Street. The spot is about 250 yards from the present bank of the Thames. The whole area was excavated to a depth of about 10½ feet from the level of the pavement; below this, trenches and holes for the foundations were dug to a further depth of 6 to 8 feet. The section on the south side of the excavation is here given.

The relations of the various rocks of the district lying to the North and South of Nuneaton have already been discussed by Prof. Lapworth from the data afforded by investigation in the field. He put into my hands many specimens of the different rocks for the purpose of microscopical examination. I have also received specimens from Mr. W. J. Harrison, and have collected some myself. Mr. J. J. H. Teall has also placed at my disposal a number of slides which he has had prepared from material of his own collecting.

The claims of the sea as a denuding agent have been much disputed of late years; the meteoric and fluviatile theories of denudation have been revived; and the glacial theory has been extended, so as to encroach on what was once generally admitted to be the legitimate province of the sea. But, as a forgetfulness of, as well as too much reliance on, the power of the sea to modify, may become a fertile source of hasty and false generalization, it is well that the importance of waves, tides, and currents, as denuding causes, should be re-asserted, and attention directed afresh to the more striking monuments they have left behind them in regions removed from their present theatre of action. These monuments present an unmistakeable resemblance to the cliffs, buttresses, walled inlets, pillars, needles, &c., now in course of being formed by the sea; and in explaining them, the old principle of sound theorization —similar effects are referable to similar causes —is not to be set aside by overstraining the capabilities of any theory which will merely account for the phenomena.

Recumbent shear folds and their related structures in the Mylor Slates are briefly described. It is concluded that folding has been produced by subhorizontal shearing stresses acting in a northwesterly or south-easterly direction.

As shown by his paper on “The Age of the Rocks and Topography of Middle Northern Iceland” (Geol. Mag., LXXV, 1938, 289–296), Dr. Hawkes realizes the great change of view concerning fundamental features of Icelandic geology necessitated by my discoveries in North Iceland of Pleistocene metamorphic glacial deposits. In fact, the changes involved seem to him so great that he finds the whole thing incredible, and he rejects what he terms my hypothesis. In this incredulity, I think, is to be found the reason for his being unable to repeat for himself some observations I made on the eastern side of Fnjóskadal. That I should have been mistaken is, I think, out of the question; a typical “striated pavement” is something a geologist of some experience cannot be mistaken about. In Skridugil I exposed a surface which quite definitely exhibited traces of glacial action. That “similar deposits” to those overlying the pavement “are found at various horizons in the older Tertiary Series of Iceland” (Hawkes, op. cit., p. 293) is unknown to me. The name “Skridugil” was given to me by a man who may not have understood to which locality I was referring.