It is well known that the crushing teeth of the Pycnodont fishes as a rule are arranged with striking regularity upon the bones which bear them, the vomer in the upper jaw and the splenials in the lower jaw. They are disposed in longitudinal series, gradually increasing in size backwards, and there is only one genus satisfactorily known (Mesodon) in which there is any marked tendency towards the frequent disturbance of this linear arrangement.

Alternation of morphogenetic systems conditioned by wide swinging of climatic belts equatorward and poleward has been used to explain otherwise puzzling relict forms in many regions. A characteristic finely dissected landscape relief prevalent in some middle-latitude regions is in strong contrast with smoothed, coarse-textured, whalebacked, relatively featureless relief in others, notably western Europe, which are now in the humid-temperate zone. This latter is believed to be relict from the periglacial regimes of Pleistocene ice ages. In New Zealand where the former landscape type is typically developed, there has also been quite strong “periglaciation”, and in Europe running-water erosion cannot but have operated to some extent in interglacial ages. It appears that the periglacial smoothing has been pushed to the extreme limit in Europe but that its effects have been neutralized in New Zealand by the vigour of dissection in the alternating warm ages. Periglacial smothering, or “fossilization”, of fine-textured relief, which has been followed by renewed fine dissection, is very common at Wellington, New Zealand. The reasons are not clear why running water should have been (and should still be) more efficient in dissecting the New Zealand landscape than that of Europe, so that the relict periglacial landscape remains intact in the latter region.

This paper presents a comprehensive study of the zircon geochronology, geochemistry and Sr–Nd isotope geology of Devonian mafic rocks developed in the East Kunlun orogenic belt, northern Tibetan Plateau, and reveals their mantle sources, petrogenesis and geodynamic implications for continental exhumation. The zircon geochronology of typical samples indicates that these mafic rocks crystallized at 406∼408 Ma. They can be classified into two different groups based on petrographic observations and geochemical compositions. Group 1 rocks exhibit low TiO2 and FeOt contents and Nb/Y ratios and have enriched mid-ocean ridge basalt (E-MORB)-like compositions with slight negative Nb and Ta anomalies. However, Group 2 rocks have distinctly high TiO2 and FeOt contents and Nb/Y ratios, comparable to typical Fe–Ti-rich mafic rocks worldwide. All the samples exhibit weak enrichments in light rare earth elements, Nb and Ta relative to the primitive mantle. Based on geochemical and isotopic studies, Group 1 rocks are suggested to be derived from depleted asthenospheric mantle that was metasomatized by c. 3–5 % continental crustal components, while Group 2 rocks originated from partial melting of enriched lithospheric mantle. The high contents of Fe, Ti and Nb for Group 2 rocks could be attributed to a high degree of olivine crystallization under low fO2 conditions with delayed nucleation of Fe–Ti oxides. Combining those results with other geological data, we conclude that slab break-off was the key factor causing exhumation of eclogites and triggering flare-up of the Devonian magmatism, and that continental collision or continental subduction may have initiated at 431∼436 Ma.

The age of the youngest part of the Sholeshook Limestone Formation is reconsidered in the light of recent advances in knowledge of Ashgill trilobite faunas. A low Rawtheyan (Zone 5) age is suggested and correlations are proposed with Ashgill rocks in the SW Berwyns and with part of the Swindale Limestone Formation of Cross Fell. The Cautleyan/Rawtheyan boundary is a level at which faunal changes are sufficiently pronounced to permit reliable and precise correlation.

The discovery of species of Kootenia and Bailiella known from the Middle Cambrian of western Newfoundland (“Pacific Province”) and southeastern Newfoundland (“Atlantic Province”) in limestone within volcanic rocks near New World Island, eastern Notre Dame Bay, is the first demonstration of the presence of Cambrian in the volcanic belts in North America, and also shows the mixing of forms from the two provinces.

The discovery of an active oil seepage in Corallian sandstones at Osmington Mills, near Weymouth, led in 1937 to an examination of the adjacent Poxwell or Moigns anticline by geologists of the D'Arcy Exploration Company, a subsidiary of the Anglo-Iranian Oil Company, Ltd. The investigations, carried out by Dr. C. T. Barber in the earliest stages, and subsequently by the junior author, consisted of surface mapping assisted by pits, trenches, auger holes, and shallow bore-holes, and culminated in the drilling of a test well in the crestal area of the anticline. This note summarizes the more important information obtained with regard to stratigraphy and tectonics.

A new enantiornithine bird is described on the basis of a well preserved partial skeleton from the Upper Cretaceous Qiupa Formation of Henan Province (central China). It provides new evidence about the osteology of Late Cretaceous enantiornithines, which are mainly known from isolated bones; in contrast, Early Cretaceous forms are often represented by complete skeletons. While the postcranial skeleton shows the usual distinctive characters of enantiornithines, the skull displays several features, including confluence of the antorbital fenestra and the orbit and loss of the postorbital, evolved convergently with modern birds. Although some enantiornithines retained primitive cranial morphologies into the latest Cretaceous Period, at least one lineage evolved cranial modifications that parallel those in modern birds.

One of the world’s most notable intraplate volcanic regions lies on the eastern Australian plate and includes two age-progressive trails offshore (Tasmantid and Lord Howe seamount chains) and the world’s longest continental hotspot trail (Cosgrove Track). While most studies agree that these chains formed by the rapid northward motion of the Australian plate over a slowly moving mantle source, the volcanic output along these trails, their plate–mantle interactions and the source of the magmatism remain unconstrained. A geophysical mapping and dredging campaign on the RV Southern Surveyor (ss2012_v06) confirmed the prolongation of the Lord Howe Seamount Chain to the South Rennell Trough, ∼200 km further north than previously sampled. Radiometric dating of these new samples at 27–28 Ma, together with previously published results from the southern part of the chain, indicate straightforward northward motion of the Australian plate over a quasi-stationary hotspot as predicted by Indo-Atlantic and Pacific hotspot models. A peak in Lord Howe Seamount Chain magmatism in late Oligocene time, also seen in the Tasmantid and Cosgrove trails, matches a 27–23 Ma slowdown of Australian plate motion. The average magma flux of the Lord Howe hotspot is estimated at 0.4 m3 s−1, similar to rates of crustal production at the South Rennell Trough prior to cessation of spreading in middle Oligocene time, supporting a potential genetic relationship to this spreading system. In addition, plate tectonic modelling suggests that the seamounts and plateaus in the Coral Sea may host the earliest evidence of plume activity in the area.

The Midland Valley region of Scotland contains the world's largest known development of igneous rocks carrying primary analcite. These rocks have been described in several publications during the last fifteen years, and some new rock-types have been defined.

Study of profiles, perpendicular to the fold-axes, shows that the folding is disharmonic. Nearly every s−surface is one of décollement. In some exposures the quartzites are reduplicated by superposed recumbent-folds without infolds of other material. The contacts are tectonic and not stratigraphic. Incipient boudinage is frequent, and nearly all surfaces show well-developed b−lineation.

The Middle Jurassic of Yorkshire consists of non-marine strata, known collectively as the Estuarine Series, and several intercalated marine bands. The non-marine beds have the characteristics of deposits formed as a delta rather than in an estuary, and are, in fact, strongly reminiscent of the Coal Measures in their general appearance. In the coast section, where they are admirable exposed, which are usually due to the presence of false bedded sediments replacing the normally parallel bedded strata. Thick wedges of sandstone replacing the Dogger, and sometimes part of the Upper Lias too, have been described by Dr. Rastall and Fox-Strangways. They are particularly noticeable when they interrupt the top seam (i.e. the Dogger) in the iron mines, where they are called “freestone baulks” by the miners. The same phenomenon is better known in the Coal Measures, where the term “washout” is used for a mass of sandstone suddenly replacing coal. Although there are several objections to the term “washout”, it is used here since it had become so well established in Coal Measures geology.

The Zagros hinterland fold-and-thrust belt is located in the central portion of the Zagros Thrust System and consists of the exhumed basement windows associated with NW-striking and NE-dipping flexural duplex structures that contain in-sequence thrusting and related folds. Mylonitic nappes of the basement were exhumed along deep-seated sole thrusts of the Zagros Thrust System. Lattice preferred orientation (LPO) c-axes of quartz show asymmetric type-1 crossed girdles that demonstrate a non-coaxial deformation under plane strain conditions. Based on the opening angles of quartz c-axis fabric skeletons, deformation temperatures vary from 425±50°C to 540±50°C, indicating amphibolite facies conditions. The estimated mean kinematic vorticity evaluated from quartz c-axis of the quartzo-feldspathic mylonites (Wm = 0.55±0.06) indicates the degree of non-coaxiality during mylonite exhumation. The estimated angle θ between the maximum instantaneous strain axis (ISA1) and the transpressional zone boundary is 17°, and the angle of oblique convergence is 57° in the M2 nappe of the basement involved. This indicates that the mylonitic nappe was formed by a combination of 62% pure shear and 38% simple shear during oblique convergence.

The age of a concretion, relative to that of the parent-rock, must be either:—

1. Contemporaneous.—The concretion grew on the sea-floor at the same time, and at about the same rate, as the surrounding deposit was laid down.

2. Penecontemporaneous.—The concretion segregated more or less close to the surface of recently deposited sediment.

3. Subsequent.—The concretion formed after deposition had finished, and after the strata had largely consolidated, but, perhaps, before cementation had taken place to any noteworthy extent.

Granulite-facies metamorphism recorded in NE Mozambique is attributed to three main tectonothermal events, covering more than 1400 Ma from Palaeoproterozoic – early Palaeozoic time. (1) Usagaran–Ubendian high-grade metamorphism of Palaeoproterozoic age is documented in the Ponta Messuli Complex by Grt-Sil-Crd-bearing metapelites, estimated to pressure (P) 0.75 ± 0.08 GPa and temperature (T) 765 ± 96°C. The post-peak P-T path is characterized by decompression followed by near-isobaric cooling. (2) Irumidian medium- to high-pressure granulite-facies metamorphism is evident in the Unango and Marrupa complexes of late Mesoproterozoic – early Neoproterozoic age. High-pressure granulite-facies is documented by Grt-Cpx-Pl-Rt-bearing mafic granulites in the northwestern part of the Unango Complex, with peak conditions up to P = 1.5 GPa and T = 850°C. Medium-pressure granulite-facies conditions recording P of c. 1.15 GPa and T of 875°C are documented by Grt-Opx-Cpx-Pl assemblage in mafic granulites and charnockitic gneisses of the central part of the Unango Complex. (3) Tectonothermal activity during the Ediacaran–Cambrian Kuunga Orogeny is recorded in the Mesoproterozoic gneiss complexes as amphibolite facies to medium-pressure granulite-facies metamorphism. Granulite facies are documented by Grt-Opx-Cpx-Pl-bearing mafic granulites and charnockitic gneisses, reporting P = 0.99 ± 13 GPa at T = 738 ± 84°C in the Unango Complex and P = 0.92 ± 18 GPa at T = 841 ± 135°C in the Marrupa Complex. This metamorphism is attributed to crustal thickening related to overriding of the Cabo Delgado Nappe Complex, and shorthening along the Lurio Belt during the early Palaeozoic Kuunga Orogeny.

One nearly complete specimen of the new Oscillatoriaceae-like filamentous microfossil Doushantuonema peatii gen. et sp. nov. is described from the Sinian (late Precambrian) of western Hubei Province, China. This constitutes the first reliable record of the Oscillatoriaceae-like filaments in the Precambrian rocks of China.

A study of Devonian faunas from North Cornwall shows that a considerable area of beds hitherto regarded as Upper Devonian are of Middle Devonian age. Goniatite localities at Trevone Bay and Portquin correlate with the Upper Maenioceras Stufe of Germany: other localities within the area mapped as Grey Slate by the Survey are also Middle Devonian. Only the area marked as Purple and Green Slate by the Survey has yielded Upper Devonian goniatites.

A freshwater and land molluscan assemblage from an Ipswichian stream channel at Maxey, Cambridgeshire, is discussed. The presence of Belgrandia marginata and Vallonia enniensis suggests that summer temperatures may have been somewhat warmer in the Ipswichian period. The assemblage represents the silting processes under relatively quiet water conditions, possibly in a side channel or backwater of a meandering river system.

One of the characteristic features of the warmer and intertropical regions of the globe, is the presence in abundance of those highest forms of Crustacea, the Shore- and Land-crabs.

On no branch of geology has there been more imaginative writing than upon metamorphism. Some speculations have, indeed diverged into the humorous. Keen-eyed observers, with vision capable of piercing through miles of solid rock, have described to us those processes of subterranean cookery by which Pluto has converted sandstones and shales into granite, metamorphic schists and porphyries. If water was used, the rocks were “stewed”; if not they were only “baked” or perhaps “melted.” Furthermore, it was declared, and text-books submissively taught, that rocks of almost every epoch have sometimes undergone these mystic changes: In North America, some metamorphic schists were “Triassic” while in the European Alps we had granite and gneiss of “Eocene” age. In Britain, men were more moderate, and we were not asked to extend our faith beyond the limits of the Palæozoic formations. The evidence on which these conclusions were advanced was mainly of two kinds. A metamorphic rock associated with unaltered beds was proved to be of the same age as the latter, because either it overlay or passed into them. Thus, as an illustration of the former, the newer gneissic rocks of the Northern Highlands were said to be Ordovician, because they rested on Ordovician limestone and quartzite. Murchison saw the gneiss lying on the top of the limestone or the quartzite, and he said that the upper beds were the younger. Everybody believed him, except Nicol, who died discredited and disheartened. Now, we know that Nicol was right, and the great authority, misled by superficial appearances, was wrong.