Abstract The Rheic Ocean is a persistent feature of Paleozoic palaeogeographies whose closure contributed to the development of the Variscan Orogen and the formation of Pangaea. Geological and geophysical data indicate repeated episodes of Paleozoic rifting and plate convergence around SW England and the adjacent offshore areas. SW England occupied a lower plate position during the Devonian–Carboniferous, on the northern passive margin of the short-lived Rhenohercynian Ocean that had formed near a recently closed segment of the Rheic Ocean. Variscan plate convergence resulted in the development of the composite southwards-dipping Rheic–Rhenohercynian suture zone by the latest Devonian and inversion of the lower plate basins during the Carboniferous. Early Permian NNW–SSE extensional reactivation of this suture zone controlled the development of the Western Approaches basins in its hanging wall and provides an excellent example of Wilson cycle structural inheritance. The onshore expression of this episode includes shear zones and detachment faults consistent with top-to-the-SSE extensional reactivation of Variscan thrust faults. There is a progression to higher-angle brittle extensional faults that cut out earlier structures. Exhumation of the lower plate was accompanied by Early Permian mantle and concomitant crustal partial melting, the construction of the Cornubian Batholith and W–Sn–Cu fracture-hosted mineralization.

The Hemerdon W–Sn deposit, being worked at Drakelands Mine near Plymouth by Wolf Minerals, is centered upon a subvertical, NNE-SSW striking, 100+ m wide Early Permian granite dyke hosted by Devonia...

A contribution on the lithostratigraphy and palaeoenvironments of Devonian, Carboniferous and Permian successions onshore in Great Britain, prepared for an international project, is summarised with particular reference to south-west England. Devonian and Carboniferous successions present in that region occur in the Rhenohercynian Tectonic Zone, to the south of the Variscan Front (VF), and their complexity reflects formation in six composite basins. They differ substantially from contemporaneous successions north of the VF. Whereas Devonian successions south of the VF are largely marine, those to the north are continental. Carboniferous successions south of the VF are predominantly marine, but shallow-water and deltaic facies occur in the highest formations. North of the VF, marine conditions were superseded by paralic and continental sedimentation. Erosion, following Variscan tectonism, resulted in the Permian successions generally resting unconformably upon older Palaeozoic rocks. In southwest England a continental succession may extend, with depositional hiatuses, from the latest Carboniferous to the Late Permian and is the most complete Permian succession in Great Britain. However, the position of the Permian–Triassic boundary in the south-west, and elsewhere in the country, is not yet resolved.

This is the first volume of the Geological Conservation Review (GCR) of Great Britain to be published in the Proceedings of the Geologists’ Association (PGA), and it is a great pleasure to see this important Earth Science publication within the pages of this long established Geological journal (2011 is the 153rd year of publication of the PGA). In many ways the PGA is a natural home for the GCR publications as it is an international journal that covers the whole range of Earth Science, but has a tradition of outreach and interaction with society not typical of many other Earth Science journals. Indeed the Geologists’ Association has long been concerned with Geoscience discovery and the impact of Earth Science on society, and the GCR is the archive that provides the key information about the critical Earth Science sites in the British Isles. These sites cover all aspects of the subject, from topics like the Marine Devonian, which is the subject of this issue (Leveridge, 2011a), to sites of geomorphological significance which may provide critical evidence by which we can evaluate topics such as flood risk, or sites of palaeontological significance which may provide clues for our understanding of the development of life on this planet. In addition the GCR provides the critical information necessary for evaluating the legal status of sites designated as Sites of Special Scientific Interest (SSSIs) in Great Britain and as such it has a status not usually found in Earth Science documents. The publication of the GCR in the PGA gives the journal a new role and means that the journal has practical impact which is in line with the impact requirements of our research councils and the objectives of the Research Excellence Framework (REF), used to evaluate UK higher education.

The report revises and expands upon the 1976 and 1978 publications for the Dinantian and Silesian, respectively, combining them into a single account of British and Irish Carboniferous stratigraphy. The need to update the two Special Reports reflects the considerable advances in Carboniferous geology over the last 30 years. The report covers developments in international chronostratigraphy and incorporates wholesale reassessments of British lithostratigraphy. A huge volume of biostratigraphical information has been published over recent decades and the report summarizes the key information.Carboniferous rocks have long been of economic importance, but it is the search for hydrocarbons, in its infancy at the time of the previous reports, which has greatly increased our understanding of Carboniferous successions offshore and at depth, particularly in southern and eastern England.

The North Devon Basin, situated in a more proximal passive margin regime than the rift basins to the south, is not constrained but its succession is thought to represent in large part the sediments debouched from a northerly hinterland. Rather than that immediate source being South Wales an original location of the basin well to the south-east and west of the Ardennes massif is considered probable, with its present position being attained by Carboniferous displacement along the Bristol Channel-Bray Fault. The basin's thick (6000 m) succession comprises terrestrial and marine deposits that form two major sedimentary cycles, which are apparently closely linked to rift basin formation to the south. The GCR sites span a relatively straightforward shelf succession that extends from the late Early Devonian to the Carboniferous. The sedimentology, palaeontology, and depositional environments of terrestrial and marine facies lithostratigraphical units are detailed, some sites providing the macrofossil assemblages important in the identification and definition by Sedgwick and Murchison of the Devonian System.

The SW England Rhenohercynian passive margin initiated with rift-related non-marine sedimentation and bimodal magmatism (Late Lockhovian). Continued lithospheric extension resulted in the exhumation of mantle peridotites and limited seafloor spreading (Emsian-Eifelian). Variscan convergence commenced during the Late Eifelian and was coeval with rifting further north. Collision was marked by the Early Carboniferous emergence of deep marine sedimentary/volcanic rocks from the distal continental margin, oceanic lithosphere, pre-rift basement and upper plate gneisses (correlated with the Mid-German Crystalline High of the Saxothuringian Zone). Progressive inversion of the passive margin was strongly influenced by rift basin geometry. Convergence ceased in the Late Carboniferous and was replaced by an extensional regime that reactivated basin controlling/thrust faults and reorientated earlier fabrics (Start-Perranporth Zone). The resultant exhumation of the lower plate was accompanied by emplacement of the Early Permian SW England granites and was contemporaneous with upper plate sedimentary basin formation above the reactivated Rhenohercynian suture. The Rhenohercynian passive margin probably developed in a marginal basin north of the Rheic Ocean or, possibly, a successor basin following its closure. The Lizard ophiolite is unlikely to represent Rheic Ocean floor or associated forearc (SSZ) crust. The Rheic and Rhenohercynian sutures may be coincident or the Rheic suture may be located further south in the Leon Domain. To cite this article: R.K Shail, B.E. Leveridge, C. R. Geoscience 341 (2009). (C) 2008 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.

This second edition of The Geology of England and Wales is considerably expanded from its predecessor, reflecting the increase in our knowledge of the region, and particularly of the offshore areas. Forty specialists have contributed to 18 chapters, which cover a time range from 700 million years ago to 200 million years into the future. A new format places all the chapters in approximately temporal order. Both offshore and economic geology now form an integral part of appropriate chapters.Most of England and Wales is formed from part of a single terrane, Avalonia, and its pre-Cambrian (Neoproterozoic) history is preserved in patches. However the time intervals from the Cambrian to the present day are well represented in our sequences and the Cambrian, Ordovician, Silurian and Devonian systems were all defined here. William Smith's map of England and Wales was the world's first geological map of a country and the British Geological Survey's copy is reproduced in the introductory chapter. This chapter, by the editors, consists of a broad overview aimed particularly at the non-specialist while guiding the reader towards the appropriate succeeding chapters. The volume concludes with a look at the future, from the short-term effects of climate change and sea-level rise to the position of our region in a possible plate tectonic configuration 200 million years hence.While the authors have taken a ‘dynamic’ view of the evolution of the area over geological time, they have also ensured that the geological evidence on which the interpretations are based is reviewed thoroughly. Hence the volume provides a valuable resource for both Earth scientists and the broader community.