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| Hangman Sandstone Formation | |
|---|---|
| Name | Hangman Sandstone Formation |
| Type | Geological formation |
| Period | Permian |
| Lithology | Sandstone, siltstone, mudstone |
| Namedfor | Exmoor |
| Region | Somerset, Devon |
| Country | England |
Hangman Sandstone Formation The Hangman Sandstone Formation is a coastal and inland geological formation on the Exmoor and Morte Bay coasts of North Devon and Somerset in England. It comprises fluvial and deltaic siliciclastic strata that record sedimentation during the late Permian to early Triassic transition, and it is notable for its role in regional studies of basin evolution, palaeoclimatology, and hydrogeology. The formation crops out prominently at sea cliffs and river valleys, contributing to studies by institutions such as the British Geological Survey, the University of Exeter, and the Natural History Museum, London.
The Hangman Sandstone Formation lies within the structural framework influenced by the Variscan orogeny, the Bristol Channel Basin, and the post-orogenic basins that include the London Basin and the Wessex Basin. Regional mapping by the British Geological Survey and academic teams at the University of Oxford and the University of Plymouth has shown relationships with adjacent units such as the Bideford Formation and the overlying Mercia Mudstone Group. Field exposures along the Bristol Channel and the North Devon coast have made the formation a reference for studies of continental red-bed sequences comparable to units studied in the South Wales Coalfield and the Pennines.
Stratigraphically, the Hangman Sandstone Formation is composed predominantly of feldspathic and quartzose sandstones, interbedded with siltstones and mudstones; locally thin conglomerates occur at basal levels. Petrographic and sedimentary analyses performed by researchers affiliated with the Geological Society of London and the Royal Society emphasize grain size distributions, cross-bedding, and palaeocurrent indicators akin to those described in the Old Red Sandstone and the New Red Sandstone. Detrital mineral suites suggest provenance links to uplifted Variscan terranes and reworked Cornubian batholith sources mapped by investigators from the University of Cambridge.
Biostratigraphic and magnetostratigraphic work, supported by palynological studies at the Natural History Museum, London and radiometric constraints from regional volcanic horizons, constrain deposition to the latest Permian into the earliest Triassic—a time interval also examined in global contexts by teams at the Smithsonian Institution and the University of California, Berkeley. The timing coincides with major Earth-system perturbations documented in the Permian–Triassic extinction event literature and in comparable sections studied in the Karoo Basin and the South China Block.
Although largely a siliciclastic red-bed unit with limited body-fossil preservation, the Hangman Sandstone Formation yields trace fossils, plant fragments, and isolated vertebrate trackways that have drawn comparisons to assemblages reported from the Mesozoic of Germany and the United States. Trace fossils and ichnofabrics documented by researchers at the Natural History Museum, London and the University of Bristol are interpreted alongside palynological assemblages similar to those from the Mercia Mudstone Group and the Sherwood Sandstone Group, aiding correlations with the Permian floras studied in the Royal Botanic Gardens, Kew collections.
Sedimentological features—large-scale cross-bedding, channel fills, and fining-upward sequences—support interpretation of fluvial-deltaic and braided-river systems influenced by seasonal aridity, comparable to depositional models developed for the Hils Group and the Fennan Sandstone. Paleocurrent data collected by field teams from the University of Exeter and the British Geological Survey align with a sediment transport direction toward proto-Bristol Channel depocentres, with climatic narratives paralleling studies from the Zealandia-adjacent basins and the Karoo Basin.
Locally, durable sandstones from the Hangman Sandstone Formation have been quarried historically for building stone in towns such as Lynton and Porlock, and have been used in infrastructure projects documented by regional archives at the Somerset County Council and the Devon County Council. The formation influences groundwater resources and engineering geology assessments overseen by the Environment Agency and has been included in geotourism initiatives promoted by English Heritage and the National Trust for the Exmoor National Park.
Key coastal exposures are protected within the Exmoor National Park and by local conservation designations administered by the National Trust and the Marine Management Organisation, while scientific access is coordinated with the British Geological Survey and university partners. Notable cliff sections at Hangman Point and along the Ilfracombe Bay coastline remain important for education and research, with monitoring programs run in collaboration with the Environment Agency and local authorities to manage erosion and preserve stratigraphic sections of interest to the Geological Conservation Review.
Category:Geologic formations of England