Proceedings of the Geologists Association最新文献

{"title":"Rock-slope failure scars on sandstone mountains in NW Scotland","authors":"Colin K. Ballantyne","doi":"10.1016/j.pgeola.2024.05.003","DOIUrl":"10.1016/j.pgeola.2024.05.003","url":null,"abstract":"<div><p>Amongst the most neglected landforms in formerly glaciated mountain environments are the scars of major rock-slope failures where the displaced rock or runout debris has been removed by glacial erosion. The characteristics of 33 such debris-free failure scars (DFFSs) on Torridonian sandstone terrain were analysed. These range from 0.011 to 0.183 km² in ground area, and scar volume implies removal of ~<!--> <!-->0.4–9.9 Mt of rock. Failure planes are planar or stepped at gradients of 37–50°, implying failure as ‘rough’ translational slides; most probably represent former rock avalanches or fragmented rockslides where shear through bedding planes resulted in runout fragmentation. Extension of 85 % to the slope crest is consistent with coseismic triggering during periods of glacio-isostatic crustal uplift. At least ten DFFSs demonstrably pre-date expansion of the last ice sheet at ~<!--> <!-->35 ka, and at least five probably represent failure that occurred in the Lateglacial interval of ~<!--> <!-->16–11.7 ka. Fourteen are located within cirques, confirming the importance of RSFs in cirque extension during ice-free interglacials or interstades; others have contributed to trough widening and the formation of arêtes. Older upper-slope cavities in Torridonian mountains are probably also the results of (possibly recurrent) rock-slope failures. It is concluded that the large-scale morphology of the Torridonian sandstone mountains reflects a long-term synergic relationship between alternating episodes of glacial erosion and rock-slope failure: reduction of rock-slope stability during each glacial-deglacial cycle has predisposed slopes to eventual failure, with subsequent glacial removal of displaced blocks and runout debris.</p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 4","pages":"Pages 355-368"},"PeriodicalIF":1.2,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0016787824000208/pdfft?md5=d791d011d347d7dc24948d6acecc9a46&pid=1-s2.0-S0016787824000208-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141984947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Barthélémy Faujas de Saint-Fond (1741–1819) and his work on pozzolans and lime: A pioneer in sustainable building","authors":"","doi":"10.1016/j.pgeola.2024.04.004","DOIUrl":"10.1016/j.pgeola.2024.04.004","url":null,"abstract":"<div><p>Barthélémy Faujas de Saint-Fond (Montélimar, France, 1741–1819) is a renowned scientist whose work on volcanoes influenced the birth of volcanology. In the meantime, he developed a strong interest in the use of natural pozzolan which he recognised as a key ingredient of durable Roman mortars. Indeed, he recognised the similarity of pozzolans from Pozzuoli (the cradle of Roman pozzolan, which gave the name to this product) and newly discovered pozzolans from various places in France. Within 18th and 19th century renowned cement scientists, it is of interest to emphasise the work of Faujas de Saint-Fond. In the current trend to develop sustainable binders based on pozzolans and low-CO₂ activators, his work on pozzolan-lime mixes is worth recalling today.</p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 4","pages":"Pages 481-485"},"PeriodicalIF":1.2,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0016787824000154/pdfft?md5=3572b11c69a4fe2af6c3a8555dd5913a&pid=1-s2.0-S0016787824000154-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140773748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The anatomically preserved Early Carboniferous flora of Pettycur, Fife, Scotland","authors":"Andrew C. Scott","doi":"10.1016/j.pgeola.2024.06.001","DOIUrl":"10.1016/j.pgeola.2024.06.001","url":null,"abstract":"<div><p>The Late Viséan (mid-Mississippian) anatomically preserved flora from Pettycur, Fife, Scotland is one of the most significant plant assemblages (lagerstätte) from this period anywhere in the world. It has been known from the later 19th century, mainly from loose limestone blocks found on the beach. Thin sections of limestones showing outstanding permineralised plants offered a number of the most eminent British palaeobotanists of their day to describe many of the plants. Most of the thin sections were made commercially so that an understanding of the formation of the deposit as a whole proved difficult. The peel technique developed in the 1950s allowed large slices of limestone to be peeled but only small pieces of the peels were ever mounted and studied by the new authors. Large collections (more than 100) of loose blocks on the beach and from <em>in situ</em> from within basaltic lava flows by the author and colleagues from the late 1970s onwards have been slabbed and peeled and provide the opportunity for new studies and an assessment of the plant assemblages and possible communities present. At least 25 plant organ species are present representing more than 13 whole plant species. Of particular significance is the occurrence of the four main lycopsid tree types that dominate later Pennsylvanian peats and the occurrence of five ferns. It is shown also that a number of the plants may also be preserved as charcoal, especially zygopterid ferns such as <em>Metaclepsydropsis</em>. Of particular importance is the occurrence of true permineralised peats that provide evidence of the botanical composition of the earliest peat-forming mire at a time of rapid global change with a sudden fall of atmospheric CO₂ and rise in O₂ that would have also had an effect upon wildfire systems.</p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 4","pages":"Pages 389-415"},"PeriodicalIF":1.2,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0016787824000294/pdfft?md5=78d2a83e6cb244ec5fe08ce311dcc495&pid=1-s2.0-S0016787824000294-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141615014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Soft-sediment deformation and glacitectonite formation during the deglaciation of the Allt Cuaich catchment, Grampian Highlands, Scotland","authors":"Emrys Phillips,&nbsp;Jon W. Merritt","doi":"10.1016/j.pgeola.2024.06.003","DOIUrl":"10.1016/j.pgeola.2024.06.003","url":null,"abstract":"<div><p>This paper presents the results of a detailed study of a deformed sequence of Late Devensian<span><span> glacifluvial sands, gravels and diamictons exposed within river cliff sections cut by the Allt (river) Cuaich, northeast of Dalwhinnie in the Grampian Highlands of Scotland. Macroscale sedimentological and structural field observations are combined with micromorphological and microstructural analysis to investigate the ice-marginal processes which led to the deposition and subsequent deformation of these glacifluvial to glacilacustrine deposits. Sedimentological evidence indicates that water-lain deposits in the area are capped by till and record the eastward </span>progradation<span> of ice-proximal fans into water ponded by an ice margin that advanced up valley from the west/southwest. These glacifluvial/ice-marginal fan sequences were deformed and subsequently overridden by ice that advanced (at least 6 km) into the Cuaich catchment. A suite of similar, but undeformed ice-marginal fans and laminated glacilacustrine deposits were laid down during the subsequent withdrawal of ice down-valley. Microstructures present within the variably glacitectonised (folded, faulted) laminated sands, silts and clays reveal a complex history of local glacial readjustments in a dynamic ice-marginal aqueous setting. Brittle–ductile shearing, liquefaction<span> and remobilisation<span>, and extensional brittle faulting accompanied the deposition of an overlying till. A detailed model of brittle–ductile shearing and glacitectonite formation during the overriding of water-rich ice-marginal deposits involves initial proglacial thrusting and folding, followed by continued submarginal to subglacial brittle–ductile shearing and extensional faulting. The study supports growing evidence that in Scotland the British Ice Sheet underwent localised expansion towards the end of the main Late Devensian glaciation (Dimlington Stadial, 26–13 ka radiocarbon years BP). In addition, it clearly demonstrates that the complex polyphase deformation recorded by glacitectonised sequences may not simply be a product of intense subglacial deformation, but a result of progressive proglacial to submarginal deformation, followed by subglacial shear as the ice progressively overrides a preexisting sedimentary sequence.</span></span></span></span></p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 4","pages":"Pages 438-457"},"PeriodicalIF":1.2,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141707195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new record of coleoid arm hooks from the lowermost Jurassic of Lilstock, Somerset","authors":"Simon Penn ,&nbsp;Malcolm B. Hart ,&nbsp;Gregory D. Price","doi":"10.1016/j.pgeola.2024.05.006","DOIUrl":"10.1016/j.pgeola.2024.05.006","url":null,"abstract":"<div><p>We report on a new assemblage of coleoid arm hooks found in the Blue Lias (Lower Jurassic) succession near Lilstock (Somerset, UK). As there are no soft tissues or other materials (ink sac, phragmocone, <em>etc.</em>) preserved in the vicinity of the hooks, the genus and species cannot be accurately identified. Unlike the hooks of <em>Clarkeiteuthis</em>, which have distinctive inflated, bilobate bases, the hooks discussed herein are delicate, with a gently curved apex, which makes them quite similar to the arm hooks of <em>Belemnotheutis</em> or <em>Acanthoteuthis</em><span>. The assemblage of hooks shows a distinct organisation and, in some places, the hooks are clearly aligned as they would have been in life position. Comparable material of late Jurassic age from the Etches Collection (Kimmeridge, Dorset) is compared to the new arm hook assemblage.</span></p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 4","pages":"Pages 486-491"},"PeriodicalIF":1.2,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141700166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New dinosaur tracks from the Middle Jurassic red beds of the Middle Atlas (Morocco): Application of photogrammetry to ichnology and conservation of geological heritage","authors":"Mustapha Amzil ,&nbsp;Mostafa Oukassou ,&nbsp;Jens N. Lallensack ,&nbsp;Hendrik Klein ,&nbsp;Omar Zafaty ,&nbsp;Hafid Saber ,&nbsp;André Charrière ,&nbsp;Christian Meyer ,&nbsp;Gerard D. Gierliński","doi":"10.1016/j.pgeola.2024.06.004","DOIUrl":"10.1016/j.pgeola.2024.06.004","url":null,"abstract":"<div><p><span>The El Mers I and II formations (Middle Jurassic, Bathonian) are geological units outcropping in the folded Middle Atlas of Morocco rich in body and trace fossils of dinosaurs. The numerous tracksites of these units have been little studied and are severely affected by ongoing erosion (</span><em>e.g.</em>, seasonal flooding) and, to a lesser degree, human activities (<em>e.g.</em><span>, urbanisation). The aim of this project is to fully document and interpret the dinosaur tracks of two historic sites and four new sites discovered in the El Mers area using digital photogrammetry<span>. The ichnofauna comprises abundant tracks and trackways of theropod and sauropod dinosaurs as well as of probable crocodylomorph tracks. The theropod tracks include several footprints of high anatomical fidelity, but the majority of the discovered tracks are identified to be penetrative tracks, with one site preserving abundant swim tracks. The sites preserve both small and enormous sauropod tracks. The enormous sauropod tracks are among the largest known worldwide, with a pes track length of up to 130 cm. The obtained 3D models are compared with site maps created by analogue mapping performed more than 15 years ago of the historical sites, revealing how erosion has both destructed surfaces and exposed new ones. The application of photogrammetry allows for the rapid collection of accurate high-resolution data with sustainable costs. The resulting 3D models can be used in research to digitally conserve threatened sites, and as a basis for knowledge transfer to the public. The present contribution encourages the intellectual, logistical, and social involvement of the local population to collaborate with scientists for the conservation of the rich geological heritage. Furthermore, scientific investigations in this area could shift from academic-only research to research focused on conservation and geotourism initiatives that involve local communities.</span></span></p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 4","pages":"Pages 458-480"},"PeriodicalIF":1.2,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141716081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carboniferous wildfire revisited: Wildfire, post-fire erosion and deposition in a Mississippian crater lake","authors":"Andrew C. Scott","doi":"10.1016/j.pgeola.2024.06.002","DOIUrl":"10.1016/j.pgeola.2024.06.002","url":null,"abstract":"<div><p>Fires have been shown to have been common in many Carboniferous ecosystems worldwide yet we still have little understanding of the detail of what, where and how such fires occur or indeed their effects both on the local ecosystem as well as on the Earth System as a whole. The Kingswood Limestone, of late Viséan (Mississippian age) found near Pettycur in Fife, Scotland, is interpreted as being deposited within a crater lake. The limestone contains a range of volcanic clasts together with charcoalified and uncharred plants. Two distinctive communities existed. One dominated by the small scrambling lycopsid <em>Oxroadia</em> that is permineralised and a second dominated by a range of pteridosperms and other gymnosperms preserved as charcoal. Fires surrounding a crater lake charred the plants that were then washed into the lake by post-fire erosion. All plant organs are found as charcoal including woody axes, leaves, pollen organs and ovules. <em>Oxroadia</em> that was living close to the lake was not affected by fire. Rising lake and sea levels allowed saline water to be introduced to the lake and connection to the sea was established. Many new charcoalified plants have still to be formally described. The Kingswood flora, together with the nearby Pettycur flora represents two of the most important Mississippian plant sites globally.</p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 4","pages":"Pages 416-437"},"PeriodicalIF":1.2,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0016787824000300/pdfft?md5=5ab3868c0d6f462cf1ea3a5daf205517&pid=1-s2.0-S0016787824000300-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141692577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A thin-skinned thrust model for ice-marginal glacitectonic detachment and emplacement of Carboniferous bedrock rafts at Kilcummin Head, NW Ireland","authors":"David P. Vaughan ,&nbsp;Emrys Phillips ,&nbsp;Jonathan R. Lee ,&nbsp;Jane K. Hart","doi":"10.1016/j.pgeola.2024.04.001","DOIUrl":"10.1016/j.pgeola.2024.04.001","url":null,"abstract":"<div><p>This paper presents the results of a detailed macro- and microscale structural study of the glacitectonised sequence at Kilcummin Head on the western side of Killala Bay, County Mayo, northwest Ireland. The sequence comprises two laterally extensive, thrust-stacked rafts of Carboniferous limestone and mudstone emplaced upon the <em>in situ</em> bedrock of the Ballina Limestone Formation. Restored cross-sections reveal that the glacitectonised sequence has undergone extensive deformation and shortening of 61 %. This accompanied the formation of a prominent thrust-moraine associated with a northward ice advance across Killala Bay during the Midlandian (Devensian). A five-stage model is proposed to describe the deformation. Stage 1 comprises detachment of the rafts, and the majority of the sequence shortening. North-directed transport of the rafts occurred on a major décollement surface located at the base of the rafted sequence, marked by a mudstone-rich glacitectonite. Stage 2 accommodated further shortening <em>via</em> a series of imbricate thrusts leading to the stacking of the bedrock rafts (Stages 3 and 4). Stage 5 saw final stacking of rafts within a prominent thrust-block moraine, followed by the deposition of a sequence of coarse-grained, ice-marginal glacigenic deposits.</p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 3","pages":"Pages 260-281"},"PeriodicalIF":1.2,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141055406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A re-evaluation of Scelidosaurus remains from Ireland and the importance of apomorphy-based identifications","authors":"Kieran G. Satchell","doi":"10.1016/j.pgeola.2024.03.002","DOIUrl":"10.1016/j.pgeola.2024.03.002","url":null,"abstract":"<div><p><em>Scelidosaurus</em> is a herbivorous dinosaur belonging to the ornithischian clade Thyreophora. Until recently, its distribution was limited to the cliffs of Charmouth, on the south coast of Dorset, United Kingdom. In 2021, a fragmentary specimen from Lower Jurassic strata in Northern Ireland (BELUM K3998) was referred tentatively to <em>Scelidosaurus</em>. This bone, the proximal end of a femur, was suggested to be an ornithischian based on several characteristics, including gross morphology and osteohistology. This study reassesses these characteristics, and finds no evidence to support their use for identifying this specimen as either an ornithischian or <em>Scelidosaurus</em>. With the most comprehensive studies on <em>Scelidosaurus</em> finding no autapomorphies of the proximal femur, this study regards BELUM K3998 as Dinosauria indet. Additionally, this study highlights the importance of apomorphy-based approaches in taxonomy and the benefits of such methodologies.</p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 3","pages":"Pages 349-351"},"PeriodicalIF":1.2,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140272329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The first Protosiren remains preserved in ornamental limestones, Middle Eocene, North Eastern Desert, Egypt","authors":"Ahmed Mamdouh ,&nbsp;Ramadan M. El-Kahawy ,&nbsp;Mohamed AbdelGawad ,&nbsp;Gebely Abu El-Kheir","doi":"10.1016/j.pgeola.2024.04.005","DOIUrl":"10.1016/j.pgeola.2024.04.005","url":null,"abstract":"<div><p>A recent revelation has come to our attention, revealing the remarkably well-preserved post-cranial remains belonging to <em>Protosiren</em>. These remains include vertebrae, ribs, and fragmentary bones, and were discovered from two different horizons located in the Mokattam Formation of El-Galala Plateau, North Eastern Desert of Egypt. The first specimen, GCU0101, is identified as <em>Protosiren</em> sp., whereas the GCU0201 specimen is recognised as <em>Protosiren</em> cf. <em>P. fraasi</em> due to certain distinguishing features. These include vertebrae with wide keyhole-shaped neural canals, reduced tuberculum on the ribs, lack of pachyostotic ribs, and the possession of rugose articular rib head. This discovery is remarkable, as it offers a unique opportunity to study the ancient marine mammal's morphology and osteology, shedding light on its evolutionary history and ecological niche. The study documents the first occurrence of <em>Protosiren</em> from an ornamental limestone of the Middle Eocene (Bartonian) Observatory Formation from El-Galala Plateau, Northeastern Desert, Egypt.</p></div>","PeriodicalId":49672,"journal":{"name":"Proceedings of the Geologists Association","volume":"135 3","pages":"Pages 310-320"},"PeriodicalIF":1.2,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140756193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}