Tuesday, 28 March 2017

Qarmoutus hitanensis: A Marine Catfish from the Late Eocene of the Valley of Whales, Egypt.

Catfish, Siluriformes, are the most abundant group of freshwater Fish, comprising rougly 22% of all Fish found in non-marine waters. While most Catfish groups are exclusively found in freshwater ecosystems, two groups, the Ariidae and Plotosidae, are found in marine waters. The Plotosidae are Eel-like Catfish found in the Indo-Pacific Region, which lack a fossil record, while the Ariidae, are found on continental shelves, brackish waters, and some freshwater ecosystems in tropical regions around the Atlantic, Indian and Pacific Oceans. The Ariidae first appear in the fossil record in the Cretaceous of North America, reaching Europe in the Palaeocene and Africa and Asia in the Eocene. The Eocene fossil record of the Ariidae in Afrca comprises fragmentary material from Nigeria,  Libya and Egypt, but to date no intact specimens.

In a paper published in the journal PLoS One on 1 March 2017, Sanaa El-Sayed, Mahmoud Kora and Hesham Sallam of the Vertebrate Paleontology Center at Mansoura University, Kerin Claeson of the Department of Anatomy at the Philadelphia College of Osteopathic Medicine, Erik Seiffert of the Department of Cell and Neurobiology at the University of Southern California, and Mohammed Antar of the Department of Geology and Paleontology at the Egyptian Environmental Affairs Agency, describe a new species of Ariid Catfish from the Qarun Formation of the the Wadi El-Hitan (Valley of the Whales) site of the Fayum Depression of northern Egypt.

The Wadi El-Hitan location is noted for the production of numerous intact Vertebrate fossils, notably Whales (hence the name) from a shallow marine environment. It is home to the earliest known fully marine Whales, but has also produced a variety of other fossils, including Crocodiles, Sirenians and Fish. The site was made a UNESCO World Heritage Site in 2005.

The new species is named Qarmoutus hitanensis, where 'Qarmoutus' derives from the Arabic word for Catfish and 'hitanensis' means 'from Hitan'. The species is described from a series of disarticulated elements presumed to have come from a single individual, namely a nearly complete neurocranium, a partial right dentary, a pair of opercles, a left suspensorium, a left pectoral girdle (cleithrum articulated with pectoral spine), the first and second dorsal spines, two paired nuchal plates, the Weberian apparatus and three disarticulated abdominal vertebrae. These are estimated to be about 37 million years old, and can be confidently assigned to the Ariidae due to their distinctive surface sculpture.

 Dorsal view of the left neurocranium and nuchal plates of Qarmoutus hitanensis. (A) Photograph and (B) Line drawing. Anatomical abbreviations: afo, anterior cranial fontanelle; anp, anterior nuchal plate; ar.pstt, articulation facet for posttempro-supracleithrum; ext, extrascapular; fn, fenestra; fopth, foramen for ophthalmic nerve; fr, frontal; le, lateral ethmoid; le.lh, lateral ethmoid lateral horn; me, mesethmoid; mg, medial groove of the neurocranium; pnp, posterior nuchal plate; prp4, parapophysis of the fourth vertebra; pt, pterotic; sc, symplectic canal; sp, sphenotic; suoc, parieto-supraoccipital; suoc. pr, parieto-supraoccipital process; W.cc, Weberian compound cenrum; 1st ptg, first pterygiophore. El-Sayed et al. (2017).

See also...

http://sciencythoughts.blogspot.co.uk/2016/12/panaqolus-tankei-new-species-of-tiger.htmlhttp://sciencythoughts.blogspot.co.uk/2014/09/a-new-species-of-armoured-catfish-from.html
http://sciencythoughts.blogspot.co.uk/2014/05/a-new-species-of-armored-catfish-from.htmlhttp://sciencythoughts.blogspot.co.uk/2014/01/terrestrial-hunting-in-european-catfish.html
http://sciencythoughts.blogspot.co.uk/2013/12/a-new-species-of-catfish-from-minas.htmlhttp://sciencythoughts.blogspot.co.uk/2013/11/two-new-species-of-armored-catfish-from.html

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Asteroid 2017 FJ passes the Earth.

Asteroid 2017 FJ passed by the Earth at a distance of 762 600 km (1.98 times the average distance between the Earth and the Moon, 0.51% of the average distance between the Earth and the Sun), slightly after 3.00 pm GMT on Tuesday 21 March 2017. There was no danger of the asteroid hitting us, though had it done so it would have presented no threat. 2017 FJ has an estimated equivalent diameter of 4-14 m (i.e. it is estimated that a spherical object with the same volume would be 4-14 m in diameter), and an object of this size would be expected to explode in an airburst (an explosion caused by superheating from friction with the Earth's atmosphere, which is greater than that caused by simply falling, due to the orbital momentum of the asteroid) in the atmosphere between 43 and 27 km above the ground, with only fragmentary material reaching the Earth's surface.
 
The calculated orbit of 2017 FJ. Minor Planet Center.

2017 FJ was discovered on 17 March 2017 (four days before its closest approach to the Earth) by the University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount Lemmon in the Catalina Mountains north of Tucson. The designation 2017 FJ implies that the asteroid was the ninth object (object J) discovered in the second half of March 2017 (period 2017 F).

2017 FJ has a 721 day orbital period and an eccentric orbit tilted at an angle of 3.43° to the plane of the Solar System, which takes it from 0.92 AU from the Sun (i.e. 92% of he average distance at which the Earth orbits the Sun) to 2.23 AU from the Sun (i.e. 2.23% of the average distance at which the Earth orbits the Sun, considerably outside the orbit of the planet Mars). It is therefore classed as an Apollo Group Asteroid (an asteroid that is on average further from the Sun than the Earth, but which does get closer). This means that close encounters between the asteroid and Earth are common, with the last having occurred in May 2015 and the next predicted in February 2019.  

See also...

http://sciencythoughts.blogspot.co.uk/2017/03/asteroid-2017-fd3-passes-earth.htmlhttp://sciencythoughts.blogspot.co.uk/2017/03/fireball-meteor-over-british-columbia.html
http://sciencythoughts.blogspot.co.uk/2017/03/comet-144pkushida-passes-earth.htmlhttp://sciencythoughts.blogspot.co.uk/2017/03/asteroid-2017-ev-passes-earth.html
http://sciencythoughts.blogspot.co.uk/2017/03/asteroid-2017-ds109-passes-earth.htmlhttp://sciencythoughts.blogspot.co.uk/2017/03/comet-2pencke-reaches-perihelion-and.html
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Cyclone Debbie makes landfall in Queensland.

A cleanup operation is underway in Queensland, Australia, after Cyclone Debbie made landfall between Bowen and Airlie Beach on Tuesday 28 March 2017, leaving a trail of devastation about 50 km across. One man is in hospital with serious injuries following a wall collapse in Prosperine, and authorities are reporting a single known death, though they have not yet released any details of this, and have expressed fears that there may be further casualties in remote communities cut off by the storm. Around 25 000 people were evacuated from homes directly in the path of the storm, and about 48 000 homes have been left without power, with warnings being issued about the dangers of downed power lines. Flooding has been reported around Prosperine, and evacuees returning to their homes are being warned to expect extensive damage.
 
Trees being battered by high winds and rain at Arlie Beach as Cyclone Debbie passes. Reuters.

Cyclone Debbie is recorded to have been a Category Four storm as it made landfall, that is to say a storm with sustained windspeeds in excess of 209 kilometers per hour (a sustained windspeed is defined as a windspeed recorded continuously for periods in excess of a minute), though the storm has lost energy as it has passed over land, though high winds are expected in the area till at least Wednesday 29 March. 

 The passage of Cyclone Winston till 07.00 GMT on Tuesday 28 March 2017  (thick line) with its predicted future path (thin line, circles represent the margin of error on the predictions). Colours indicate the strength of the storm. Tropical Storm Risk.

Tropical cyclones are caused by solar energy heating the air above the oceans, which causes the air to rise leading to an inrush of air. If this happens over a large enough area the inrushing air will start to circulate, as the rotation of the Earth causes the winds closer to the equator to move eastwards compared to those further away (the Coriolis Effect). This leads to tropical storms rotating clockwise in the southern hemisphere and anticlockwise in the northern hemisphere.These storms tend to grow in strength as they move across the ocean and lose it as they pass over land (this is not completely true: many tropical storms peter out without reaching land due to wider atmospheric patterns), since the land tends to absorb solar energy while the sea reflects it.

 View of Cyclone Debbie from the International Space Station. Force 13.

The low pressure above tropical storms causes water to rise there by ~1 cm for every millibar drop in pressure, leading to a storm surge that can overwhelm low-lying coastal areas, while at the same time the heat leads to high levels of evaporation from the sea - and subsequently high levels of rainfall. This can cause additional flooding on land, as well as landslides.

See also...

http://sciencythoughts.blogspot.co.uk/2016/09/evacuations-begin-amid-widespread.htmlhttp://sciencythoughts.blogspot.co.uk/2016/02/twenty-one-confirmed-deaths-after.html
http://sciencythoughts.blogspot.co.uk/2016/01/widespread-flooding-in-southeast.htmlhttp://sciencythoughts.blogspot.co.uk/2015/12/landslide-destroys-house-in-victoria.html
http://sciencythoughts.blogspot.co.uk/2015/04/three-confirmed-dead-as-floods-and.htmlhttp://sciencythoughts.blogspot.co.uk/2015/03/at-least-eight-dead-as-cyclone-pam.html









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Cascolus ravitis: A Leptostracan Crustacean from the Silurian Herefordshire Lagerstätte.

Leptostracan Crustaceans are small, filter feeding Arthropods found from the intertidal zone to the abyssal ocean plains, though most are found at depths of less than 200 m. They are a small group, with less than 50 known extant species and a very limited fossil record. However, they are considered to be the most primitive, and therefore earliest appearing, members of the Malacostra, the wider group that also includes major Crustacean groups such as the Decapods, Amphipods and Isopods, making their evolutionary history very interesting to palaeobiologists.

In a paper published in the Proceedings of the Royal Society Series B: Biological Sciences on 22 March 2017, David Siveter of the Department of Geology at the University of Leicester, Derek Briggs of the Department of Geology and Geophysics and Yale Peabody Museum of Natural History at Yale University, Derek Siveter of Earth Collections at the University Museum of Natural History in Oxford and the Department of Earth Sciences at the University of Oxford, Mark Sutton of the Department of Earth Sciences and Engineering at Imperial College London and David Legg, also of the Department of Earth Sciences at the University of Oxford, describe a new species of Leptostracan Crustacean from the Silurian Herefordshire Lagerstätte.

The Herefordshire Lagerstätte comprises a large number of small (at most centimetres) organisms from the Middle Silurian (about 425 million years ago). The organisms are preserved in three dimensions within calcareous nodules within a layer of volcaniclastic sediments (i.e. a volcanic ashfall in a marine environment), and can only be accessed using computerised tomography scanning techniques. Brachioods, Polychaete Worms, Gastropods, Aplacophorans, Chelicerates, Marrellomorphs, Mandibulates, Barnacles, Phyllocarids, Ostracods, Starfish and Sponges have all been found in the Herefordshire Lagerstätte; together these are known as the Herefordshire Biota.

The new species is named Cascolus ravitis, in honour of naturalist and broadcaster David Attenborough; Cascolus derived from the Latin for dweller in a fortified building (the Middle English meaning of Attenborough), while ravitis derives from Ratae (the Latin name of Leicester, where Attenborough grew up), vita (Latin for life) and commeatis (Latin for messenger). It is described from a single specimen 8.9 mm in length, preserved within a calcareous nodule in three dimensions with soft tissue intact, following serial grinding at 20 μm intervals and reconstruced as a three dimensional model using the SPIERS software suite which enables reconstruction and analysis of tomographic (serial image) datasets, such as those obtained from serial-grinding of specimens, or from CT scanning.

 Holotype of Cascolus ravitis, exoskeleton and soft parts (OUMNH C.29698): (a–u) ‘virtual’ reconstructions (a,b,f,h–k,m–u are stereo-pairs); (v) specimen in rock. The exact boundary between structures such as body and limbs, as indicated by colour changes, is somewhat arbitrary. (a) Dorsal view. (b) Ventral view. (c) Anterior part of head, appendages omitted, ventral view. (d ) Posterior part of trunk, appendages omitted, ventral view. (e) Right lateral view. (f ) Part of trunk, dorsal view. (g) Head and most of the trunk, appendage 1 omitted, posterodorsal view. (h) Head with appendages and trunk segments 1 and 2 with appendages omitted; ventral view. (i) Anteroventral view. ( j ) Limb base and proximal part of antennules, right ventral oblique view. (k) Antennae, right anteroventral oblique view. (l ) Anterolateral view. (m,n) Mandible, left limb: posterior oblique (m) and right anteroventral oblique (n) views. (o) Maxillula, left limb, posterior oblique view. ( p) Sternites 3–6, anteroventral view, appendages omitted. (q) Maxilla, left limb, posterior oblique view. (r–t) Trunk appendage 2, left limb: gnathobase (r) and complete limb (s) posterior oblique views; and inner proximal part of endopod (t) posterior oblique medial view. (u) Trunk appendage 5, left limb, posterior oblique view. ai, axial inflation; as?, apodous segments?; ba, basipod; bi, bell-shaped inflation; e1, e2, epipods; en, endopod; ex, exopod; f1–f3, flagella; fu, furrow; hi, indentation in anterior margin of the head shield; gn, coxal gnathobase; h1–h5, head appendages; hr, half-ring of trunk tergite; ie, inflation adaxially forward of each eye (‘eye ridge’); la, labrum; lb, limb base; no, node; or, occipital ring; pa, precoxal area; pe, pedunculate eye; t1–t9, trunk appendages; te, end of the trunk, masked by extraneous matter; tr, trunk; tu, tubercle(s). Numbers refer to trunk segments and trunk tergites/sternites as appropriate. Arrows in (m-o, t) indicate podomere boundaries. Arrow in (s,u) indicates a spine/seta. Scale bars: (a–q), (s–v) are 0.5 mm; (r) is 0.1 mm. Siviter et al. (2017).

Cascolus ravitis has a head with five pairs of appendages and a head shield, followed by nine limb-bearing segments then two (probably) limbless segments. The head shield is smooth and elongate, with a ridge running between the eyes. All limbs except the first are biramous (split in two).

See also...

http://sciencythoughts.blogspot.co.uk/2016/12/iphiculus-eliasi-new-species-of.htmlhttp://sciencythoughts.blogspot.co.uk/2016/10/rosagammarus-minichiellus-not-amphipod.html
http://sciencythoughts.blogspot.co.uk/2016/05/decapod-crustaceans-from-tarioba-shell.htmlhttp://sciencythoughts.blogspot.co.uk/2015/01/a-new-species-of-icriocarcinid-crab.html
http://sciencythoughts.blogspot.co.uk/2014/11/a-new-species-of-ostracod-from.htmlhttp://sciencythoughts.blogspot.co.uk/2014/07/ghost-shrimps-from-oligocene-and.html
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Saturday, 25 March 2017

Eruption on Mount Kambalny, Kamchatka, for the first time in over 250 years.

The Kamtchatka Volcanic Eruption Response Team has issued a warning to aviation following an eruption on Mount Kambalny on the southern Kamchatka Peninsula on Friday 24 March 2017. The stratovolcano (cone-shaped volcano made up of successive layers of ash and lava) erupted suddenly for the first time since 1769, producing an ash column 7-8 km high that drifted around 255 km to the southwest. The eruption is not thought to present any immediate threat to Human life due to the remote location of the volcano. The area is occasionally visited by parties of tourists, but none are thought to have been in the vicinity at the time of the eruption.

MODIS/TERRA satellite image of ash from Mount Kambalny (dark grey) drifting to the southwest of the volcano. Kamchatka Volcanic Eruption Response Team.

Mount Kambalny is the southernmost active volcano on the Kamchata Peninsula, and rises 2156 m above sea level (1970 m above the surrounding plain). The volcano probably began erupting in the early Holocene (i.e. slightly less than 10 000 years ago), with much of the current structure formed in a series of large eruptions and collapses about 6300 years ago. The last major eruption on the volcano probably took place about 600 years ago, with all activity halting in the 1760s, though fumerole activity (emissions of volcanic gas) is frequently recorded on the related Pauzhetka volcanic field, a tectonic depression to the north of Mount Kambalny, thought to be a volcanic caldera and containing the 14 by 10 km Kurile Lake.

The Kamchatka Peninsula lies on the eastern edge of the Okhotsk Plate, close to its margin with the Pacific and North American Plates. The Pacific Plate is being subducted along the margin, and as it does so it passes under the southern part of the Kamchatka Peninsula, and as it does so is partially melted by the friction and the heat of the Earth's interior. Some of the melted material then rises through the overlying Okhotsk Plate as magma and fuelling the volcanoes of southern Kamchatka.

See also...

http://sciencythoughts.blogspot.co.uk/2016/07/eruption-on-mount-klyuchevskoi.htmlhttp://sciencythoughts.blogspot.co.uk/2015/12/eruptions-on-mount-zhupanovsky.html
http://sciencythoughts.blogspot.co.uk/2014/08/two-dead-and-one-missing-after.htmlhttp://sciencythoughts.blogspot.co.uk/2014/05/eruption-on-shivaluch-produces-10-km.html
http://sciencythoughts.blogspot.co.uk/2014/04/eruption-on-mount-karymsky-produces-21.htmlhttp://sciencythoughts.blogspot.co.uk/2013/12/eruption-on-mount-kizimen.html
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Dinosaur phylogenetics, a radical new proposal.

Phylogenetics is the study of the relationships between organisms, as determined by examining similarities between species and reconstructing family trees. The early origins of the science relied very much on informed guesswork, but modern phylogenetics is a highly mathematical discipline, in which practitioners attempt to measure mathematically differences between the morphologies, or better still DNA, of different species, and allow computer models to estimate the most likely relationships between them. The phylogeny of the Dinosaurs, although it has changed a great deal in detail with the discovery of numerous new species, has remained essentially the same since 1887, with the earliest Dinosaurs appearing in the Middle-to-Late Triassic and rapidly diverging into two distinct groups the ‘Lizard-hipped’ Saurischians and the ‘Bird-hipped’ Ornithischians, and the Saurischians splitting shortly afterwards into the Sauropods and Theropods.

In a paper published in the journal Nature on 23 March 2017, Matthew Baron of the Department of Earth Sciences at the University of Cambridge and the Department of Earth Sciences at the Natural History Museum, David Norman also of the Department of Earth Sciences at the University of Cambridge and Paul Barrett also of the Department of Earth Sciences at the Natural History Museum describe a radically different phylogeny for the Dinosaurs, based upon a new study which incorporated data on 457 morphological characteristics of 74 taxa of Dinosaurs and Dinosauromorph Archosaurs (i.e. Archosaurs thought to be closely related to Dinosaurs). 

Remarkably Baron et al. did not recover the two ‘Saurischian’ Dinosaur groups as being one-another’s closest relatives to the exclusion of the Ornithischians; rather they produced a model in which the Dinosaurs split early into two groups, one comprising the Sauropods plus the Herrerasauridae (a group of early Dinosaurs generally thought to be primitive Theropods) and the other comprising the Ornithischians plus all other Theropods.

Phylogenetic relationships of early dinosaurs. Time-calibrated strict consensus of 94 trees from an analysis with 73 taxa and 457 characters. (A) the least inclusive clade that includes Passer domesticus, Triceratops horridus and Diplodocus carnegii — Dinosauria, as newly defined. (B) the least inclusive clade that includes Passer domesticus and Triceratops horridus — Ornithoscelida, as defined. (C) the most inclusive clade that contains Diplodocus carnegii, but not Triceratops horridus —Saurischia, as newly defined. All subdivisions of the time periods (white and grey bands) are scaled according to their relative lengths with the exception of the Olenekian (Early Triassic), which has been expanded relative to the other subdivisions to better show the resolution within Silesauridae and among other non-Dinosaurian Dinosauromorphs. Baron et al. (2017).

If this is correct, then it presents a number of serious challenges for our understanding of Dinosaur phylogeny. Firstly there is the definition of the term 'Dinosaur' itself. The current definition of Dinosaur is 'Passer domesticus, Triceratops horridus, their most recent common ancestor and everything descended from it'. This made sense because Passer domesticus, the modern House Sparrow, is a highly derived Theropod and Triceratops horridus, is a highly derived Ornithischian, so that a clade comprising all the descendants of their most recent common ancestor and everything descended from it, would, if Theropods and Ornithischians are the most distantly related Dinosaur groups, include everything we would consider to be a Dinosaur. However, if Ornithischians and Theropods are more closely related to one-another than either group is related to the Sauropods, then Sauropods can no longer be considered to be Dinosaurs. Since this goes completely against the common understanding of the term Dinosaur, Baron et al. suggest that rather than exclude the Sauropods from the Dinosaurs, the definition of the group should be amended to 'Passer domesticus, Triceratops horridus and Diplodocus carnegii, their most recent common ancestor and everything descended from it', thereby retaining everything that we would think of as being a Dinosaur within the group.

Then there is the problem of how to split the Dinosaurs into subgroups. The taxon Saurischia, which comprises the Theropods plus the Suaropods, and which has for over a hundred years been seen as one of the major Dinosaur divisions, is no longer valid under this hypothesis. Baron et al. suggest that instead the term Ornithoscelida, first proposed by Thomas Huxley in 1870 to describe a group comprising the Compsognatha (Theropods), Iguanodontidae (Ornithischians), Megalosauridae (Theropods) and Scelidosauridae (Ornithischians), i.e. a group of Dinosaur clades thought to be unrelated since the Ornithischian/Saurischian split was proposed in 1887, but which now appears valid. They retain the term Saurischia to describe the clade that includes the Sauropods and Herreosaurs, as these groups were both fall within the original definition of that group.
This hypothesis also has implications for the origins of the Dinosaurs, and the nature of the earliest members of the group. Since the earliest Therapods (the Herrerasauridae) and the earliest Ornithischians (the Heterodontosaurids) were both thought to have been carnivores, and the earliest members of the most closely related non-Dinosaurian group, the Silesauridae, were also thought to have been carnivores, it was presumed that the earliest Dinosaurs were probably carnovores, but it was unclear what they would have been like. However if the Herrerasauridae are outside the Theropods, then this balance changes. The earliest member of the Theropods become Eoraptor, a small omnivorous Dinosaur with heterodont dentition (i.e. different shaped teeth in different parts of the mouth) and grasping hands, while the earliest Ornithischians, the Heterodontosaurids, were also small with heterodont dentition and grasping hands, as were the Prosuaropods (earliest Suaropods). Only the Herrerosaurs differe from this pattern, being small with grasping hands but having serrated, recurved teeth reminiscent of later Theropods and indicatinve of a hypercarnivorous diet (diet in which little or no vegetable food is ingested), however, this group is not well known, and it is possible that early member of the group did have a different form of dentition. This points to a model where the earliest Dinosaur would have been a small, omnivorous animal with grasping hands and heterodont dentition, a versatile generalist lifestyle and anatomy that could explain how the Dinosaurs were able to diversify rapidly into so many different niches.

See also...

http://sciencythoughts.blogspot.co.uk/2017/02/isaberrysaura-mollensis-neornithischian.htmlhttp://sciencythoughts.blogspot.co.uk/2017/02/a-hesperornithiform-bird-from-late.html
http://sciencythoughts.blogspot.co.uk/2017/01/tingmiatornis-arctica-ornithurine-bird.htmlhttp://sciencythoughts.blogspot.co.uk/2016/12/preserved-plumage-in-immature.html
http://sciencythoughts.blogspot.co.uk/2016/12/tongtianlong-limosus-new-species-of.htmlhttp://sciencythoughts.blogspot.co.uk/2016/11/ixalerpeton-polesinensis-buriolestes.html
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Friday, 24 March 2017

London school closed by sinkholes linked to disused mine workings.

A school in northwest London has been forced to close after a series of sinkholes that opened up in its grounds were found to be linked to disused mineworkings running beneath the site. The first hole appeared in a car park at Pinner Wood School in Harrow appeared in the summer of 2015, prompting Harrow Council to commission an investigation into the site by geotechnical consultants Peter Brett Associates. This survey used laser survey borehole equipment to determine the structure of the ground beneath the school and discovered a series of tunnels, believed to be abandoned early nineteenth century mineworkings, running through a chalk layer 20 m below the surface. These tunnels appear to be beginning to collapse, raising concerns about the safety of structures above them, which has caused Harrow Council to close the school indefinitely while attempts are made to remedy the situation. Lessons will be held at other education facilities in the borough for the time being; it is not yet certain when (or if) it will be possible for the school to reopen.

Digital model of the tunnels below Pinner Wood School. Harow Council.

Sinkholes are generally caused by water eroding soft limestone or unconsolidated deposits from beneath, causing a hole that works its way upwards and eventually opening spectacularly at the surface. Where there are unconsolidated deposits at the surface they can infill from the sides, apparently swallowing objects at the surface, including people, without trace.

See also...

http://sciencythoughts.blogspot.co.uk/2016/05/car-swallowed-by-sinkhole-in-london.html
http://sciencythoughts.blogspot.co.uk/2016/11/sinkhole-traps-coach-in-south-london.html


http://sciencythoughts.blogspot.co.uk/2015/04/magnitude-19-earthquake-in-essex.html
http://sciencythoughts.blogspot.co.uk/2015/05/magnitude-42-earthquake-off-coast-of.html
http://sciencythoughts.blogspot.co.uk/2015/03/homes-evacuated-after-sinkhole-opens-up.htmlhttp://sciencythoughts.blogspot.co.uk/2015/01/building-3d-geological-model-of-london.html
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