Stop the press: The Jurassic Coast starts in the Permian

Mervyn Jones (UK) This Geologists’ Association field meeting followed the publication of Professor John Cope’s Geologists’ Association (GA) Guide No 73, Geology of the South Devon Coast. It is also the companion to GA Guide No 22, Geology of the Dorset Coast. John retired in 2003 after lecturing at Swansea and Cardiff universities. Since then, he has been an Honorary Research Fellow at the National Museum Wales in Cardiff, and has a wide field experience in the UK and Europe, with publications covering many fossil groups over a wide stratigraphical range. Most recently he has been working on redrawing the geological map of South Wales, the subject of an upcoming GA lecture. And, each year, for the past six years, he has provided weekend geological trips to the West Country. Fig. 1. Prof Cope demonstrates bedding and cleavage. We met up at Meadfoot Strand to the east of Torquay Harbour. Our mission for the weekend was to examine the complex Devonian succession in the Torbay area and its unconformable relationship to the Permo-Triassic cover. Of great interest was the marine Devonian, first described by Adam Sedgwick, assisted by Roderick Impey Murchison, who finally realised that these facies were contemporaneous with the familiar Old Red Sandstone found north of the Bristol Channel. Since then, the Devonian Stages have been named after rocks in the Czech Republic, Germany and Belgium. The base of the Devonian was the first ‘Global Boundary Stratotype Section and Point’ (GSSP), defined by graptolite zones at Klonk, in … Read More

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Triassic beasts and where to find them

Sue Beardmore (UK) Located amid the scenic Southern Alps, on the Swiss-Italian border, is Monte San Giorgio, a mountain that rose up like many across Central Europe as a result of continental collision between Africa and Europe during the Alpine Orogeny. It is not particularly big or distinct by alpine standards but it is special, a status emphasised by the designation of its slopes as a UNESCO World Heritage site initially in 2003 for the Swiss part with the neighbouring Italian area added in 2010. To begin, the rocks outcropping on the mountain form an almost complete stratigraphic sequence from the Permian through to the Jurassic (Fig. 1), not only an extended interval of time but an important one around the massive Permo-Triassic extinction. The same rocks provide a context for the equally important Middle Triassic vertebrate, invertebrate and plant fossils, now numbering more than 20,000, that have been found at the locality over the last 170 years. Fig. 1. A stratigraphic section of the rocks at Monte San Giorgio. © Commissione Scientifica Transnazionale Monte San Giorgio, 2014. In particular, it is the diversity, relative abundance and excellent preservation of the vertebrate fossils that has thrown the locality into the spotlight. These occur in six main fossiliferous horizons deposited in a shallow marine basin, the Monte San Giorgio Basin, one of many depressions on a carbonate platform between the Eurasian continent to the north and west, and the open waters of the vast Tethys Ocean to the south and east. … Read More

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Headbanging, rocking and moonwalking fossils

Mats E Eriksson (Sweden) One can never be too careful when given the opportunity to name a fossil organism that has proved to be new to science. In addition to a meticulous description and accompanying images showing the characteristic traits of the fossil, a unique and formal, Latinized scientific name must be attached to the creature. Many people, who get the chance honour an older colleague or famous palaeontologist, use the name of the discovery site or region to indicate the provenance of the fossil or, of course, christen the fossil after its characteristic looks (for example, Eriksson, 2017a). But you can also glance towards completely different areas, such as the art and music scenes. As a lifelong music fan and hobby musician (who, just like many of my peers, had aspiring yet quite ludicrous ‘rock star dreams’ in my teens) and a palaeontologist by profession, I cannot help myself but feeling blissful and delighted about the possibility of joining my two passions – ‘heavy’ music and palaeontology – in ‘unholy matrimony’. This has, among other things, led me to name some extinct polychaete annelid worms (bristle worms – the marine ‘cousins’ of earth worms and leeches) from the Silurian and Devonian periods after some of my favourite ‘metal’ musicians. These largely soft-bodied animals generally have poor preservation potential, although full body fossils are known from the fossil record. However, some representatives are equipped with resistant jaws (when preserved as microfossils they are known as scolecodonts) that, by contrast to … Read More

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Armboth Dyke, Lake District

Mark Wilkinson (UK) The Armboth Dyke makes a good half day geology excursion in a scenic but quiet part of the UK Lake District. Parking is on the west shore of Thirlmere, in a pay-and-display car park accessed by the narrow road that winds around that side of the lake (Grid reference NY 305 172). The car park is in an excellent setting, with direct access to the wooded lake shore, and would be a great place for the non-geologically minded to wait while you venture onto the adjacent hill. It is probably worth noting at this point that the dyke itself is mostly exposed on rather featureless rolling moorland at around 400m above sea level (Fig. 1), and might not be a good place to visit in thick mist, unless you are very confident with a map and compass. If you happen to be in the business of teaching students to make geological maps, this site makes a great practise day, without too many problems of recognising weathered rocks in the field. Fig 1. Moorland with the dyke just visible as a slightly lighter patch of rock below the red arrow, where the edge of the dyke is exposed. University of Edinburgh students for scale. So, assuming you have decent weather, leave the car park and take the path uphill from the west side of the minor road, a few metres to the north of the car park. The path is steep-ish, and can be slippery if wet, so … Read More

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Fossil folklore: Fish

Paul D Taylor and Mike Smith (UK) Fish are the most diverse animals with backbones – that is, vertebrates – living today. Bone and teeth of fishes abound in the fossil record, from the armour-plated, primitive fishes of the Devonian, through the cartilaginous sharks with their shiny dagger-like teeth, to the bones of advanced ray-finned teleosts related to modern carp and cod. Along with other marine fossils, fossil fishes were once used as ‘proof’ of the biblical deluge, for example, the fabulous Cretaceous fossil fish deposits of Lebanon. Gayet et al. (2012) recorded that, in the third century, the Bishop of Palestine wrote: That Noah’s Flood covered the highest mountains is for me the truth, and I say that the witness of my eyes confirms it: for I have seen certain fishes, which were found in my lifetime on the highest peaks in Lebanon. They took stones from there for construction, and discovered many kinds of sea fishes which were held together in the quarry with mud, and as if pickled in brine were preserved until our times, so that the mere sight of them should testify to the truth of Noah’s Flood”. Petrified nails Hugh Miller, in his book Foot-prints of the Creator (Miller, 1849), mentioned that amateur geologists of Caithness and Orkney would refer to one particular fossil in the Old Red Sandstone, presumably relatively common, as ‘petrified nails’ (Fig. 1). Fig. 1. A so-called ‘petrified nail’, about 150mm long, as depicted by Hugh Miller. These fossils represent … Read More

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Interpreting ammonite fossils

Neale Monks (UK) Ammonites are such popular and well-known fossils that suggesting they need interpreting may seem ridiculous. But for all their familiarity, there is still a good deal of debate over how they lived and what they did. If nothing else, ammonite experts all agree that they were ecologically diverse, with different species doing different things, and broadly speaking, they can be divided into ammonites that moved about close to the bottom, ammonites that actively swam about in mid-water and ammonites that drifted about on currents, rather like modern jellyfish. The aim of this article is to help you extract the maximum amount of information from the ammonite fossils in front of you. The way an ammonite shell coils is important, but so too are things like the shape of the suture line and the ornamentation visible on the surface of the fossil, which means that even fragmentary specimens can be quite informative. But first, you need to find your fossils … Where to collect ammonites Fig. 1. Folkestone, Kent. Ammonites only lived in marine environments, most often in moderately deep seas where water chemistry and salinity were more or less constant. So, the classic places to find ammonites are marine limestones (including chalks and oolites), marls, clays and shales. While ammonites seem to have inhabited a range of environments including reefs, their fossils are only occasionally common in places where coral reefs or crinoids dominate. On the other hand, sediments that contain lots of oysters, bivalves, belemnites and … Read More

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Fossil fishes of the Old Red Sandstone of Scotland

Dr Neale Monks (UK) While they can be found in many other parts of the British Isles, Scotland is uniquely associated with Palaeozoic fossil fishes. That Scotland’s fossil fishes are so well known is largely thanks to a remarkable man from Caithness, called Hugh Miller. Where scholars had dismissed the Old Red Sandstone as lacking in fossils, Miller found many finely preserved fossil fishes. He published several books on field geology including, in 1841, his most famous work, The Old Red Sandstone. This eminently readable book described the formation in great detail and included dozens of beautiful engravings that illustrated the fossil fishes he had discovered. Fig. 1. Dipterus – Achanarras Quarry (© Dr Jens Rydell). What is the Old Red Sandstone? The Old Red Sandstone is a distinctive set of sandstone rocks dominated by sediments laid down under non-marine, relatively dry climate conditions. It is predominantly Devonian in age, though, in Scotland at least, certain parts may be as old as Middle Silurian. This makes it much older than the formation known as the New Red Sandstone, which was laid down during the Permian. Fig. 2. Milleosteus remains from Thurso. (© Dr Jens Rydell.) Geologists can find Old Red Sandstone sediments across much of the British Isles, from Cornwall in the southwest of England to the Orkney Islands off the northeast tip of Scotland. For the most part, the Old Red Sandstone is indeed red thanks to the large quantities of iron oxide it contains, but, at some localities, … Read More

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