Proceedings of the Geologists Association最新文献

Scratch circles, previously defined as ‘bedding plane parallel sedimentary structures formed by the passive rotation of a tethered organism into the surrounding sediment’, have hitherto been identified in the geological record from the Ediacaran to the Paleocene, as well as in modern settings. They have not met the definition of trace fossils, being passively registered by a part of a plant. Several variations of scratch circle morphology have been identified in or on Pliocene and Pleistocene deposits on the Cape south coast of South Africa, allowing for an expansion of the scratch circle temporal range. Furthermore, these novel forms require a redefinition of the term ‘scratch circle’. Anthropogenic origins need to be considered for occurrences in the Pleistocene; guidelines to assist in distinguishing such causes from typical scratch circles are presented. Scratch circles may conceivably have inspired the creation of circular patterns (palaeo-art) in sand by Middle Stone Age hominins. Evaluation of scratch circles in snow allows for subtle features to be determined. A re-evaluation of what the term ‘trace fossil’ constitutes could be considered, in order to include the term palaeo-ichnobotany.

Construction of the Holderness/Flamborough Head moraine belt on the East Yorkshire coast, England, records the oscillatory onshore flow of the North Sea Lobe of the British-Irish Ice Sheet from ~ 25.8 to ~ 19.7 ka BP, during which time a thick sequence of multiple diamictons and associated stratified sediments were emplaced. The sedimentology of a > 40 m thick stratigraphy through the moraine belt at Filey Bay, in combination with local borehole records, is used here to reconstruct the depositional processes associated with glacier ice moving ca., 12 km onshore and damming the mouth of the Vale of Pickering, which resulted in the accumulation of an unusually thick and complex sequence of deposits traditionally classified as the “Filey till”. The base of the sedimentary sequence comprises stratified diamictons, which are interpreted as glacilacustrine deposits emplaced predominantly by sediment gravity flows in an ice-contact ‘mud apron’ on the distal slope of a subaqueous push ridge constructed in the earliest proglacial lake in Filey Bay; a vertical increase in coarse-grained lithofacies records increasing glacier proximity. Glacier overriding of the mud apron is recorded by a stacked sequence of tills that interdigitate with lake sediments inland. A zone of till-lake sediment interdigitation migrated first westward during North Sea Lobe advance and then eastward during its retreat, into and out of Glacial Lake Pickering, respectively. Multiple tills and intra-till stratified beds and lenses at the top of the sequence at Filey represent alternating deforming bed-sliding bed facies (subglacial traction tills and subglacial canal fills) associated with the construction of inset push moraines, constructed by sub-marginal incremental thickening or punctuated aggradation. This depositional scenario addresses the problems arising from genetic classifications of substantial accumulations of glacigenic diamictons as ‘till’ when modern analogues indicate only modest thicknesses of subglacial traction till beneath glaciers. Onshore thickening of glacigenic deposits through subaqueous push moraine construction and mud apron progradation is compatible with glacier surging behaviour, but not necessarily solely diagnostic of a surging North Sea Lobe during the last glaciation.

The fossil remains of a pterodactyloid pterosaur from the Kimmeridge Clay Formation (Jurassic: Tithonian) of Abingdon, Oxfordshire, central England are identified as a partial left first wing finger phalanx. The elongation of the phalanx and distinctive morphology of the proximal articular region, in particular the square outline of the extensor tendon process, permit the specimen to be assigned to Ctenochasmatoidea. Although fragmentary, it is sufficiently well preserved to determine accurately its dimensions when complete. Morphometric analysis reveals the specimen to represent one of the largest known examples of a Jurassic pterosaur, with an estimated wingspan of at least 3 m, and is one of the first pterodactyloids to be reported from the Jurassic of the United Kingdom.

The cliff and foreshore sections at Lavernock, South Wales form the type section of the Penarth Group, representing the Rhaetian stage in the UK, the latest Triassic. The Rhaetian bonebeds here have been famous for over 150 years for their vertebrate fossils. Here, we show that, unusually, the Lavernock basal Westbury Formation bonebed is dominated by osteichthyan teeth, with sharks such as Lissodus relatively rare. The rounded teeth of the durophagous bony fish Sargodon are abundant, with teeth of Severnichthys next in abundance, and Gyrolepis the rarest, quite unlike most other Rhaetian bone beds. Also, small elements such as shark denticles have not been found, whilst larger bones of marine reptiles (ichthyosaurs, plesiosaurs) and dinosaurs do occur. The dinosaur bones are unusual, and Lavernock may have yielded more such bones than any other British Rhaetian bone bed. These terrestrial elements suggest that the lower bone bed accumulated close to shore, but underwent considerable transport, with clasts perhaps moving back and forwards, to explain the abrasion of specimens, the larger elements and absence of smaller specimens. Dinosaurs are more widely documented in the Late Triassic of the Penarth area, around Lavernock, than anywhere else in the UK.

A series of historical documents by the 19th-century amateur naturalist and palaeontologist Alfred Brown report the earliest discovery of bone-bearing cave breccia in the former Transvaal (South Africa). The oldest of these reports dates from 1890 and predates the first mention of the existence of bone-bearing breccia at the famous Sterkfontein-Kromdraai caves by five years. The breccia fragment was kept by Brown in his collection, where it was noted to come from the Monte Christo gold mine near Ventersdorp (North-West Province). Brown's specimen is lost, but we could relocate the mine and confirm the presence of breccia deposits. Alfred Brown's notes are the earliest scientific report about the bone-bearing nature of Plio-Pleistocene South African caves and the first to acknowledge them as a potential source of hominin fossils, some 30 years before the discovery of the Taung Child, Australopithecus africanus. The finding strengthens the chronology of the discovery of the South African fossil hominin sites. It also significantly shortens the gap between the gold rush and the first discovery of bone-bearing breccia in the Witwatersrand.

A great range and number of journals exist to promote and disseminate local knowledge in the areas of natural history, geology, geography and ecology. Many are still active; others are lost. The journals act as mouthpieces for local societies and are a repository of local knowledge. Some are hard to locate but the websites of local societies provide information on topics covered and the regularity of publication of the journals. The loss of journals seems to be the result of the pressure on academics to publish in international outlets and the growth of highly informative websites.

In order to better constrain the structural evolution of the North–South Axis (NOSA) running through central Tunisia, a multidisciplinary approach based on geological mapping, field observations and paleostress analysis was used. The geological study of the middle part of the NOSA including the Gadoum, Akrouta, Sidi Khalif, Khechem El Kaleb and Faïd structures, showed the predominance of N–S and E–W fault sets. Movement on the faults of this fault network caused the formation of depositional areas and the collapsed and tilting of fault bounded blocks located in the Southern part of the Gadoum–Akrouta sector. The Gadoum and Akrouta Jebels formed as a result of slip and rotation on a single N–S trending listric fault in the Cenomanian during which time reactivation of both the N–S and E–W fault sets occurred. During Coniacian–Santonian times, when the Aleg Formation was being deposited, the study area was affected by a transtensive regime. This regime led to the division of the area into blocks (e.g., the Gadoum–Akrouta block and the Wadi El Abiod Syncline) and this resulted in the Aleg Formation being deposited with variable thicknesses. During the Campanian–Early Maastrichtian, a N–S transpressive regime was established, and this regime, coupled with the salt tectonics, resulted in the formation of an angular unconformity, subsidence inversion and lateral thickness variations of the Abiod Formation. During the Early Eocene, an E–W fault network affected the sedimentary basin. These faults, arranged in steps, generated accommodation spaces for sediments which increase in thickness along the North–South Axis.

Morocco hosts a wealth of geological heritage, alongside a rich and varied palaeontological heritage that dates back 1.7 billion years, and archaeological assets that chronicle the biological evolution of the human species and their cultural activities. Research into Morocco's geoheritage has pinpointed several sites and monuments, both nationally and internationally recognised, noted for their unique geological formations and aesthetic appeal. This study aims to offer a comprehensive review of the geoheritage research conducted in Morocco over the last 14 years (2008–2022). This research is sourced from databases including Scopus, Science Direct, and Google Scholar. The documents retrieved have been meticulously reviewed after isolating publications that primarily focus on Moroccan geoheritage sites. The findings indicate a growing trend in the number of studies conducted in this realm over the years. Initially, most research concentrated on the identification and characterisation of Morocco's geoheritage localities. However, with the burgeoning interest in this field, geoscientists have broadened their scope to explore diverse facets of geoheritage site evaluation, encompassing aspects such as geoparks, geotourism, geoeducation, and geoconservation.

Rhaetian seas in the latest Triassic transgressed from west to east over the southwest of the UK, reaching parts of South Wales and the North Somerset coast first. Evidence comes from marine conditions in the pre-Rhaetian Williton Member, a unit not seen further east. Here, we confirm this hypothesis with reports of diverse, Rhaetian-style fish faunas in the Williton Member, as well as evidence that the Westbury Formation bonebeds are from deeper waters than most others in the region. Our study focuses on the classic coastal section at Lilstock, which shows the entire Penarth Group and the Triassic-Jurassic boundary. The Williton Member fossil beds yield Rhaetian-type chondrichthyans (Lissodus, denticles), osteichthyan teeth (Gyrolepis, Sargodon, Saurichthys), and bivalves. The basal and higher bone beds of the Westbury Formation are dominated by osteichthyans (86.8 %, 84.7 %), with chondrichthyans relatively rare (13.2 %, 15.3 %), the opposite of what is seen at other locations in the southwest of the UK (16–59 % osteichthyans; 41–84 % chondrichthyans). The similarity of the faunal composition in the basal and higher Rhaetian bone beds is also unusual, and the dominance by bony fishes can be interpreted as evidence for deeper water than further to the east.