Abstract In March 1833 Charles Darwin discovered Devonian fossils in the Falkland Islands. He was excited by his find but could have had little premonition of the long-running geological controversy that he was initiating. Darwin's fossils matched a coeval South African fauna and, as further collections were made, the association was apparently strengthened. A particularly important contribution arose around 1910 through collaborations between a local collector, Constance Allardyce, and professional palaeontologists: Ernest Schwarz in South Africa and John Clarke in the USA. The accumulating evidence was seized upon by the early proponents of ‘displacement theory’ – continental drift – notably Alexander Du Toit, who relocated the Falkland Islands northward for his 1927 South Atlantic reconstruction. A more radical, but geologically sounder proposal arose in 1952 when Ray Adie suggested that the Falkland Islands, rotated through 180°, had originated as the eastward culmination of the Cape Fold Belt and Karoo Basin. In effect, Adie had presciently described a rotated microplate, perhaps the first on record. An opposing view saw the Falkland Islands as part of a fixed, South American promontory, and argument around these two contrasting interpretations of South Atlantic geology continues to the present day.

Abstract Rock successions in Britain and Ireland, and more especially those in Wales, were instrumental in the founding and naming of the Ordovician System, and the Anglo-Welsh series established both initially and subsequently were used widely as a standard for Ordovician chronostratigraphy. Although now largely superseded in the global scheme of series and stages, they retain their local and regional importance. The Ordovician System in Britain and Ireland documents the history of a segment of the Earth's crust that incorporated opposing peri-Gondwanan and peri-Laurentian/Laurentian margins of the Iapetus Ocean during its closure, and is accordingly complex. The complexity arises from the volcanic and tectonic processes that accompanied oceanic closure coupled with the effects of eustatic sea-level changes, including the far-field effects of the Late Ordovician glaciation. For the past three decades, Ordovician successions in Britain and Ireland have been discussed in terms of terranes. Here we review Ordovician successions in each terrane, incorporating the results of recent research and correlating those successions via biostratigraphical schemes and radiometric dates to the global Ordovician series and stages.

Abstract The deglaciation of southern Gondwana during the Early Permian was preceded by waxing and waning of the south polar ice sheet. The fluctuations in ice extent are recorded in the sedimentary record by strata separating thick deposits of glacial diamictite from post-glacial mudrock. These deposits span across all of the major Gondwana fragments, now recognized as South Africa, South America, India, Antarctica and Australia, and also occur on the Falklands and Ellsworth Mountains microplates created during break-up of the supercontinent in the Mesozoic. We present sedimentary evidence for the progression of deglaciation from the Falkland Islands microplate using a series of borehole core runs acquired during onshore mineral exploration. Glacial advance and retreat phases are inferred from the Hells Kitchen Member of the Port Sussex Formation; the rock succession that conformably overlies the main body of glacial diamictite known locally as the Fitzroy Tillite Formation. The pulsated nature of the transition to fully post-glacial conditions was accompanied by an intricate interplay of sedimentary processes, including soft sediment deformation, meltwater pulses and turbidity currents. The Falkland Islands core data lend insight into the evolving Early Permian environment and offer an unusually complete view of continental margin deglaciation preserved in the ancient sedimentary record. Supplementary material: Borehole core photographs from the Fitzroy Tillite Formation, Hells Kitchen Member and Black Rock Member for cores DD029 and DD090 are available at https://doi.org/10.6084/m9.figshare.c.4031119.v1