The structure of fold and thrust belts has been studied for just over one hundred years and has been the subject of a recent international conference at Toulouse, in May 1984. This article reviews some of the recent advances in thrust tectonics from a personal viewpoint, in the light of the Toulouse meeting. Key tools in correctly interpreting thrust systems are the use of balanced (restorable) cross-sections and the resolution of three dimensional fault systems. These analytical methods are now being widely developed and applied to numerous orogenic belts with many surprising results. While our understanding of foreland thrust belts is now probably better than any other structural environment, there is still great uncertainty as to the emplacement-driving mechanisms of these belts. Future work will try to solve these and other outstanding problems and apply the new analytical methods to the interior parts of thrust belts in efforts to restore entire orogens.

The good exposures of virtually undeformed Callovian and Oxfordian strata along the Djeffara escarpment of southern Tunisia and northwestern Libya have allowed analysis of regional depositional history during this time.

A number of lithostratigraphic problems are considered. In Tunisia, the Foum Tatahouine Formation is subdivided into members and in Libya some of the stratigraphic issues are clarified. A correlation between the two sequences is proposed. The widely claimed aeolian origin for the Libyan Chameau Mort Sandstone is rejected.

The depositional patterns of the Callovian and Oxfordian strata are described in the context of Mid and Late Jurassic sedimentation in the eastern Ghadames basin of the African craton. After a regressive Bathonian sequence, transgressive conditions commenced in Early Callovian time. In a series of continental–marine cycles, this transgressive sequence culminated in widespread shallow, restricted-marine micritic deposition. A regression in Late Callovian time resulted in emergence marked by a thin but widespread calcrete horizon. In Mid? Oxfordian time a renewed transgression brought in open marine, high-energy, shallow-water carbonates. Later, regressive conditions returned, leading to increasing restriction, and latest Jurassic time saw the first signs of the fluvio-deltaic deposition that was to dominate the region in Early Cretaceous time.

It is proposed that the usage of the term structural facing be extended to include fault structures. Fault facing is defined as the direction in a fault plane which is at right angles to the trace of the bedding and is directed towards the younger beds. Certain types of faulted structures are found to have diagnostic patterns of facing variation.

Mornes Patates is the youngest volcano in Dominica occupying a depression on the southwestern flank of a larger stratovolcano, Morne Plat Pays. Within the depression an arcuate ridge, apparently of acid andesite lavas, has been cored and largely buried by the explosive emplacement of two acid andesite domes and their associated pyroclastic deposits, mainly block-and-ash flow deposits. A basaltic scoria horizon, exposed on the northern side of the depression, has a 14C age of 28450 ± 1500 years B.P. and is not seen on the volcano itself, which suggests that the domes and pyroclastic rocks are younger than this. A 14C age of 450 ± 90 years B.P. from a block-and-ash flow deposit from the Morne Patates dome apparently confirms this and the youthful morphology also suggests a young age. The angular shape of the depression and the steep submarine slopes are consistent with an origin as a lateral gravity slide rather than a caldera collapse. Vigorous fumarolic activity and swarms of local earthquakes suggest that magma exists at depth (several kilometres) beneath the Morne Patates–Morne Plat Pays area.

The relationships of the Keisley Limestone, an isolated carbonate mudmound in the Cross Fell Inlier of northern England, have long been problematical with respect both to the other upper Ordovician as well as the Silurian strata of the inlier. Bedded limestones, separated by gaps from the Keisley mudmound below and from atavus Biozone graptolite shales above, yielded a prolific shelly fauna to Temple in 1968 which he regarded as being of lower Llandovery age. This age is controversial. To try to establish the precise ages of the rock units, the position of the Ordovician–Silurian boundary, and the detailed nature of the changes which took place at this boundary, a critical section was excavated. Bed by bed lithological and faunal collections reveal from beneath the known atavus outcrop (a) five bentonite bands, unexpected in the context of northern England, (b) graptolites of both acuminatus and persculptus Biozones above the bedded limestones and (c) a similar but distinct assemblage from siltstones associated with these limestones which contains Hirnantia elements. From the palaeontological evidence there is little doubt that the topmost part of the carbonate sequence is of Hirnantian age.

Results of detailed remapping of the Kirkcudbright area in the Southern Belt of the Southern Uplands of Scotland, together with new palaeontological data, necessitate revision of the regional structure, and re-interpretation of the sedimentary history of the northwest margin of the Lower Palaeozoic lapetus Ocean. On the east side of Kirkcudbright Bay, at least six sediment-ologically and structurally distinct, subvertical tectonic blocks can be distinguished. Recognition of the Raeberry Castle Formation as a Wenlock turbidite sequence, rather than mid- to late Llandovery as previously interpreted, removes the need to postulate the existence of an axial rise and a distinct basin adjacent to the south, in mid- to late Llandovery times.

Zoned dolomite rhombs which occur in the organic-rich Jet Rock Formation (Toarcian) of northeast England have been studied using backscattered scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray microanalysis. The rhombs, which are 5–20 μm in size, are variable in chemical composition, but many consist of a dolomite core surrounded by a zone of ferroan dolomite, ankerite or ferroan calcite. Zoned rhombs occur in early-diagenetic calcite-cemented concretions and layers as well as dispersed throughout the shales. Distributional and textural evidence suggests that they formed mainly by primary precipitation from pore fluids within the zone of bacterial sulphate reduction. The ferroan outer zones probably formed after burial below the sulphate reduction zone when insufficient H2S was available to react with all the Fe2+ in solution.

Recent investigations indicate that three distinct lithostratigraphical units can be recognized in the Red and Norwich Crag deposits of the area around Aldeburgh and Orford, Suffolk. These effectively represent a refinement of a stratigraphy originally suggested by Prestwich in 1871. A lowermost coarse-grained shelly sand, the Red Crag Formation, rests on an eroded London Clay surface and is banked against the Pliocene Coralline Crag. The Red Crag Formation passes upwards into a fine-grained generally unfossiliferous well-sorted sand, the Chillesford Sand Member, which overlaps the Red Crag Formation to rest directly on the Coralline Crag. The Chillesford Clay Member is regarded as the lateral equivalent of the upper Chillesford Sand Member, the two members together comprising the Norwich Crag Formation in this area. Sections that have been zoned palaeontologically may be integrated into this lithostratigraphical framework. These indicate that the Red Crag Formation correlates with the Pre-Ludhamian Stage, and the Chillesford Sand Member and the Chillesford Clay Member correlate with the Bramertonian Stage. Type sections are established for the three units described.

Rare pebbles of granite have been discovered in the raised Patella beach at Butterslade, Gower, South Wales. Their petrography, trace element geochemistry and the Rb/Sr whole rock age of 55 ± 5 Ma confirm that they are derived from the Lundy granite which is about 49 km to the southwest of Gower. Amino acid analyses of fossil gastropods in the Patella beach have provided an age of 210000 years. Various hypotheses of transportation of pebbles from Lundy and Pembrokeshire to Butterslade are considered. Erratics from Pembrokeshire were probably transported by Pleistocene ice into the area while clasts of Lundy granite were moved by progradation of beach deposits northeastwards towards Gower during glacio-eustatic marine transgressions in the Pleistocene.