The majority of Dicellograptus species have stipes which spiralled to a greater or lesser extent; this explains continuous variation of axial angle found in several species and many anomalous features of flattened or partially flattened specimens. The effects of variation in thecal style along the stipe are distinguished from those produced by variable orientation of the rhabdosome during flattening and by later tectonic distortion. It is concluded that Dicellograptus probably lived with stipes pointing upward and that the rhabdosome rotated in a horizontal plane due to eddies created by the non-directional ciliary activity of radially dispersed zooids in order to improve feeding efficiency.

A brachiopod fauna is described from a marine horizon within the Dartmouth Beds at Bull Cove, Cornwall. The fauna indicates a Middle or Late Siegenian age and aspects of the palaeoecology are discussed. The Lower Devonian succession of south Devon and north Cornwall is discussed and the terms Meadfoot facies and Standon facies are proposed to replace the Meadfoot Beds and Staddon Grits of the old terminology.

Successive early Upper Devonian deposits penetrated in the Willesden No. 1 Borehole, along with their associated fossils, bear testimony to changing environments attributed to movements of the shoreline. The inferences drawn from these, and from marine-influenced deposits and faunas of similar age encountered elsewhere in the concealed strata, reinforce and refine the concept of a discrete Frasnian marine transgression. The event was probably linked with a similar, mid-Frasnian, movement in northern France.

Marine fossils have been recovered from the Downtonian–Devonian sequences of nineteen boreholes in southern England, most of which include strata referable to the Frasnian or early Famennian. A revised, Frasnian, age is suggested for deposits encountered in the Brightling Borehole and part of the Bolney succession. Upper Devonian strata with marine faunas are recognized in the Ashwell, Little Chishill and Northbrook boreholes, and late Silurian or very early Devonian at Lakenheath.

Overbank deposits of the Narrator Brook, exposed by the excavation of a drainage ditch, are described. The deposits, which consist of coarse (sand and gravel), fine (silt and clay) and peat units, were laid down in a floodbasin environment. The coarse units are interpreted as crevasse-splay deposits, rather than being classified as floodbasin sediments along with the fine units. Three stages of development in the evolution of the floodbasin are identified. The first stage is represented by the development of peat at a time when the area was not subjected to flooding, the second by deposition of the fine and coarse sediment units and the third by an upper peat horizon. No precise date for the formation of the deposits is at present available, but it is thought that they may be the result of man's activity in the catchment.

Sand grains enclosed in gypsum crystals which grew in otherwise uncemented sand commonly, either float in the gypsum, or, are arrayed in sand-bearing and sand-free zones in a manner which indicates that they were displaced during growth of the gypsum. Corroborative evidence of displacement of included sand grains is found in some sandy gypsum crystals from coastal sabkhas in Abu Dhabi, U.A.E. In these crystals, dust particles which formerly coated the sand grains are strung out as festoons behind the grains and thus record the directions and extent of the displacement. The direction of displacement was outwards, normal to the traces of what had been former crystal faces. The displacement also involved some pivoting of elongate grains which now lie with their long axes in the direction of movement.

A summary has been made of the distinguishing lithological features of four sedimentary groups long recognized from the Lower and Middle Old Red Sandstone (Devonian) of the Northern Highlands of Scotland. This has led to recognition of the groups in unfossiliferous outliers to the W, permitting the correlation of these outliers with the main outcrop.

The Sulitjelma Gabbro, occurring as a member of the Sulitjelma Ophiolite Complex, and typical of the ophiolite suite in its petrography and geochemistry, is cut by a vein of trondhjemite (plagiogranite). The previous identification of the vein as an offshoot of a continental potassium-rich granite, the Furulund Granite, is wrong. Therefore the Rb-Sr isochron age of 413±34 Ma, obtained from the granite, cannot be taken as the age of intrusion of the Sulitjelma Gabbro.

Reidentification of the macrofossils from the lowest Dinantian limestones of Lilleshall, northeast of Telford, indicates that these beds are older than previously reported and that they can be correlated with the early Tournaisian Hastarian Stage. The conodonts recovered confirm this age and are characteristic of the Siphonodella–Polygnathus inornatus Assemblage Biozone. This reassessment affects the Dinantian palaeogeography of the Midlands of England and the early Tournaisian coast-line in the Lilleshall area can be redrawn further to the north than it has usually been placed.

Thin beds composed mainly of quartz and albite occur interstratified with epiclastic rocks in a thick marine Early Permian sequence in the eastern part of the New England Fold Belt, eastern Australia. The sequence has suffered very low grade regional metamorphism and the quartz-albite rocks retain few primary textural features. A pyroclastic origin for these rocks is argued on the basis of inherited sedimentary characters and their distinctive mineralogical and chemical composition, and it is suggested that they accumulated as glass-rich ash-fall tuffs. The present chemical composition of the quartz-albite rocks suggests the tuffs may have initially altered to zeolitic assemblages. Similar quartz-albite rocks, perhaps misidentified as chert or siliceous siltstone, probably occur in other low-grade metamorphic sequences, the progenitors of which accumulated adjacent to active magmatic arcs.

Computer-enhanced Landsat images reveal a 65 km arcuate lineament linking the concealed fault zone beneath Wadi Al-Batin to the central Arabian graben and trough system. Detection of the link allows a continuous 1000 km arc of faults and troughs cutting the Mesozoic-Cenozoic rocks of the Arabian Shelf to be recognized. The arc, here called the East Arabian fault zone, is interpreted as forming the western and southern boundaries of the East Arabian block, a tectonic unit underlying at least 200 000 km2 of the Arabian Peninsula.

Stratigraphical relationships within the 560 km central Arabian graben and trough system demonstrate that its faults were active during the late Cretaceous-early Palaeogene, movements ceasing when the Red Sea began to open and the Arabian subplate was established. The principal hydrocarbon fields of the Arabian Peninsula lie within the boundaries of the East Arabian block.

Analysis of a Bathonian ostracod fauna and the microflora from a claypit at Tarlton, Gloucestershire, strongly suggests that land was then nearby. Among the non-marine Ostracoda are cypridacean species similar to lacustrine forms from the French Bathonian. Such an assemblage has not previously been recorded from Britain. The clay is assigned to Bate's revised Bathonian ostracod zone 6, and a palaeogeographical interpretation is offered in terms of recent reconstructions of British Bathonian landmasses.

The history of research into the Lower Carboniferous rocks of Kent since Dines' 1933 account of the stratigraphy of the coalfield is outlined. Details of the boreholes that have proved Lower Carboniferous are listed, including notes of the significant fossils that have been identified. The age of the Lower Carboniferous rocks is discussed. Two boreholes yielded faunas of Tournaisian age and i4 proved rocks of Holkerian age. No younger Dinantian strata are known from Kent.

New, well-preserved material of the Ordovician proetacean trilobite Rorringtonia, hitherto of uncertain taxonomic position, indicates that it belongs to the aulacopleurid subfamily Scharyiinae. It also elucidates the position of another problematic proetacean, Analocaspis, which is now considered to be congeneric with Rorringtonia.

At the base of austroalpine nappes in Calabria alpine greenschist dynamometamorphism is overprinted by blueschist metamorphism. Tectonic overpressures and deep-rooted movements of upthrusting type in compressive regime are the key to generation of blueschistic conditions and to greenschist-bluecschist evolution of metamorphism. The tectonic overpressures are generated because the rocks at higher confining pressures and lower pore pressures have relatively higher resistance to deformation. The evolution from greenschist to blueschist conditions results from cooling during upward motion with overpressures remaining concentrated along the thrust zones.