The Old Red Sandstone on Anglesey, North Wales, presumed Lower Devonian in age, is folded and locally cleaved, but the intensity of this deformation has previously been understated. We describe two S-verging anticline–syncline pairs, one with a strongly overturned middle limb, their associated minor folds and an axial-planar cleavage. The intensity of the deformation calls into question a proposed link to Variscan fault displacements, and the angular unconformity below the Old Red Sandstone precludes the deformation being part of a continuous ‘late Caledonian’ phase. We consider this deformation of the Old Red Sandstone to be mid-Devonian, correlating with the Acadian phase in mainland Wales. It is predated by a Silurian shortening deformation on Anglesey that is possibly related to the closure of the Iapetus Ocean, absent in mainland Wales and the Lake District, but perhaps preserved also on the Isle of Man.

40Ar–39Ar dating by a combination of spot analysis and step-heating has been carried out on mica fabrics from slaty cleavage and a shear zone in the Neoproterozoic to Cambrian rocks of Charnwood Forest, Leicestershire. The results indicate that crust adjacent to the eastern margin of the Midlands Microcraton was affected by localized epizonal metamorphism and penetrative deformation between 425 and 416 Ma (Silurian to earliest Devonian), somewhat earlier than the Acadian Phase of the Caledonian orogeny recorded elsewhere in southern Britain. The Charnwood cleavage geometry suggests that the deformation arose within a dextral transpressional regime along the eastern margin of the Midlands Microcraton. This tectonism may have overlapped with pre-Acadian sinistral transtensional movements documented for the Welsh Basin and Lake District areas, to the west and north of the Midlands Microcraton.

The origin of the Newer Granites is long-standing problem. In the Caledonian orthotectonic zone the intrusions span the period of late orogenic convergence and uplift, but attempts to relate them as a group to late Iapetan subduction have been unsuccessful. A range of rock types is represented, mainly with I-type affinities, and granodiorite is the most voluminous. In contrast, granitic intrusions south of the Moniaive shear zone in Scotland and also in the north of England have significant S-type characteristics, span the trace of the Iapetus suture and have ages in the range 400–390 Ma, significantly younger than intrusions to the north. We refer to these younger granitic intrusions, along with others of similar character along-strike to the southwest, as the Trans-Suture Suite. We explore the link between the Trans-Suture Suite and recently recognized orogen-wide sinistral transtension in the Early Devonian period. Importantly, the Trans-Suture Suite intrusions are accompanied by an intense suite of lamprophyre dykes, the origin of which is to be sought in extension, decompression and heating of enriched Avalonian sub-continental lithosphere. In some instances the granite intrusions carry clots of lamprophyric origin and the Criffel body is particularly important in being continuously zoned from an I-type with lamprophyric enclaves to an S-type interior. We propose that generation of these lamprophyres during transtension advected heat into the base of the crust to produce the S-type component of the Trans-Suture Suite. Modelling presented shows that generation of voluminous S-type magmas requires the coincidence of several factors: hydrated sub-continental lithospheric mantle preserved during ‘soft’ collision under the Trans-Suture Suite zone; thermal relaxation to remove any subduction refrigeration; crust composed of juvenile volcanogenic material; and Devonian transtension. Our models suggest that if hydration pre-dated transtension then only small granitic bodies could be produced, unless the zone of lamprophyre generation extends beyond the rift zone. The emplacement of the Trans-Suture Suite intrusions overlapped the Acadian deformation period that succeeded the transtensional episode during which the granite magmas were generated.

Illite crystallinity data from the Silurian slate belts of England and Wales indicate anchizone to low epizone metamorphism during the Acadian deformation in late Early Devonian time. This metamorphic grade implies a substantial overburden, now eroded, of Lower Devonian non-marine sediments of the Old Red Sandstone (ORS) magnafacies. A minimum 3.5 km pre-tectonic thickness of ‘lost’ ORS is estimated in the southern Lake District and comparable thicknesses in North Wales and East Anglia. Tectonically driven subsidence of the underlying Avalonian crust is required to accommodate such thicknesses of non-marine sediment. One proposed mechanism is flexure of the Avalonian footwall during convergence that continued from Iapetus closure in the Silurian until Acadian cleavage formation in the Emsian. The evidence for this model in the critical area of northwest England is reviewed and found to be unconvincing. An alternative model is developed following a recent suggestion that the Early Devonian was a period not of continued convergence but of orogen-wide sinistral transtension. Transtensional accommodation of the lost ORS is evidenced by Early Devonian extensional faults, by synchronous lamprophyric magmatism, and by compatibility with previously diagnosed sediment provenance patterns. A summary of Siluro-Devonian tectonostratigraphy for Britain south of the Highland Border emphasizes that, unlike the Scottish Highlands, this area was not affected by the Scandian Orogeny, but was by the Acadian. An important period of sinistral transtension in the Early Devonian (c.420–400 Ma) was common to both regions. This was a time of high heat flow, lamprophyric and more evolved magmatism, and major southward sediment transport, involving mainly recycled metamorphic detritus from the Highlands and from contemporaneous volcanicity. Old Red Sandstone, deposited in coalescing transtensional basins over much of Britain from the Midland Valley to the Welsh Borders, was largely removed and recycled southward during Acadian inversion.

This study, drawing on data from a large sociolinguistic interview corpus for three Acadian communities of Atlantic Canada, concerns codeswitches involving verbs of opinion or belief (e.g. guess, think, imagine, believe) in French-English bilingual discourse. The codeswitch itself serves to underscore the speaker's stance as to the truth of the proposition – and, in some cases, to indicate a degree of uncertainty not nuanced by corresponding French language forms. Variation in usage is related to intensity of language contact at the levels of the community and of the individual.