Deposits magazine www.depositsmag.com
International rock and fossil magazine
Fossil sea urchins as hard substrates Stephen K Donovan and John WM Jagt
Mineral classics from Wales Tom Cotterell
The diversity of trace fossils from the Triassic of Winterswijk, Netherlands Henk Oosterink (Netherlands)
Also in this issue: £3.95 - $6.00 - €4.95 Echinoids Coccoliths Basalts from Skye The dinosaur relic Deciphering carpoids Issue number 20 Autumn 2009
Issue 20 Autumn 2009
Front cover
Editor Roy Bullard
The Twelve Apostles are a series of famous limestone stacks off the shore of the Port Campbell National Park, by the Great Ocean Road in Victoria, Australia. This popular tourist site was once known as the Sow and Piglets, but the name was changed in the 1950s.
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You will probably have noticed that this issue has been published slightly later than usual. So, we thank you for your patience as we know you love reading Deposits and look forward to its release. However, our Director of Production, Alister, and Research Coordinator, Alison, have just had their first child. Haeyden was born on the 25 August 2009 weighing in at a healthy 8lb 12oz. Not surprisingly, this left us a little short handed and, as with any newborn, sleepless nights and mountains of used nappies have left them a little behind schedule!
Deposits: ISSN 1744-9588
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At Deposits, we receive thousands of photos and we feel it has become important to keep these in one place and make them available to everyone to look at and comment on. We believe that this is important and represents our part in keeping a public record of some of the finds that have been made in the UK. In addition, our UK Fossils Discussion Board has always had thousands of photos of recent finds and, therefore, we have taken the decision to put these together. All of the finds and reports that you have kindly sent us will now be displayed on our new, re-vamped discussion board - the first revamp for eight years. The new discussion board is extremely powerful and we have, at our disposal, the expertise of experts from around the UK, who will help to identify and to discuss your finds. We will then choose the best photos from the “Your recent finds” board, for inclusion in this magazine. You can easily add photos of your finds by going to www.discussfossils.com and following the instructions there. Also revamped is our geological search engine, searchgeo (www.searchgeo.com), which is now much faster. Therefore, if you know of any good internet sites related to earth science, please add them in! As we draw close to the end of 2009, we would like to thank you once again for your continued support, even through these difficult economic times, and we hope that 2010 will be a better year for everyone with, of course, loads of great discoveries to be made...
Contents 26
Deciphering carpoids: fossil ‘problematica’ Dr Imran A Rahman (UK)
28
Recent finds: your finds from the summer holidays
29
Your field reports
30
Collecting rocks and minerals: a recollection Malcolm Chapman (UK)
31
Book review: Excursion guide to the geology of East Sutherland and Caithness
14
Fossil sea urchins as hard substrates Stephen K Donovan (the Netherlands) and John WM Jagt (the Netherlands)
32
Geological field trip through Scotland: basalts from the Isle of Skye Dr Robert Sturm (Austria)
17
Sands of Gobi Desert yield new species of nut-cracking dinosaur Steve Koppes (USA)
35
Book review: Death of an ocean: a geological Borders ballad
36
Echinoids Dr Neale Monks (UK)
40
Dinocochlea: the mysterious spiral of Hastings Paul D Taylor (UK) and Consuelo Sendino (UK)
42
Coccoliths: tiny fossils with immense paleontological importance Dr Robert Sturm (Austria)
4
Exploring the Jurassic at Zalas Quarry, southern Poland Tomasz Borszcz and Dr Michał Zatoń (Poland)
7
News snippets
8
The diversity of trace fossils from the Triassic of Winterswijk, the Netherlands Henk Oosterink (Netherlands)
12
This fossil: the dinosaur relic Rob Hope (France)
13
Location profile: Seasalter, Kent Joe Shimmin (UK)
18 24 25
Mineral classics from Wales Tom Cotterell (UK) Mineral focus... Redgillite Climate events let ice age mammoths go far below 40°N Dick Mol (Netherlands) and RalfDietrich Kahlke (Germany)
International rock and fossil magazine Featured find Janet found several of these Brittle Stars in the Oxford Clay, Cotswold Water Park in July. She contacted the Natural History Museum, who has told her, it is a new species!
www.recentfinds.co.uk
www.ukge.co.uk
Exploring the Jurassic at Za called rhyodacites from the early Permian. These rocks are overlain by Middle to Upper Jurassic sediments that are the main focus of this article. The Jurassic sedimentary rocks at Zalas Quarry, covered by loess and other Quaternary deposits, are clearly visible and easily reachable along the quarry wall that runs from east to west. However, if you ever decide to visit the quarry to hunt for fossils (which we really do recommend), permission from the quarry owners must be obtained first. The oldest Jurassic deposits exposed at the quarry are Figure 1. Location of Zalas Quarry against a background of the geological setting of the area. The oldest rocks in the area are represented by Carboniferous mudstones (1), conglomerates (3) and Permo-Carboniferous volcanic rocks (2 sands of nearand 4). The Mesozoic deposits (5) are mostly covered by Cenozoic mudstones (6). In many places, the rocks are cut by shore marine faults (7) and rivers (8). origin, intercalated he area of southern Poland is researchers since the 19th century, with quartzite sandstones and well known for its widespread and also amateur collectors from conglomerates. The sands are Jurassic deposits, in particular, Both Poland and elsewhere. This not overlain by fossiliferous, sandy, Middle and Upper Jurassic surprising, as the deposits contain crinoidal limestone, the name of sedimentary rocks that outcrop in abundant and diverse fossils, which is derived from the remains of a belt running from south-east to including nearly all the fossil groups stalked sea-lilies (crinoids) appearing north-west southern Poland, in the characteristic of this geological in and making up the sediments. area known as the Polish Jura Chain period. Based on ammonites, the sands and (Fig. 1). This area owes its name to In this article, we will focus on the sandy crinoidal limestones are dated the occurrence of spectacular klippes spectacular Middle to Upper Jurassic as being Early Callovian (the fourth built by white, massive limestones sequence that is exposed at the and last stage of the Middle Jurassic). deposited in the northern shelf of famous Zalas Quarry, which has been The top of this limestone is covered the Tethys Ocean during the Late actively explored since the 1870s. It by a spectacular stromatolitic layer. Jurassic (Oxfordian). Because of is located in the southern part of the Stromatolites are biosedimentary their resistance to erosion, the rocks Polish Jura Chain. structures formed by tiny, blue-green form a picturesque element in the microorganisms called cyanobacteria Locality and geology surrounding upland landscape. As and associated assemblages of other well as these, the Middle to Upper micro-organisms, like bacteria. of Zalas Quarry Jurassic deposits (in the form of Such structures were very prolific glauconitic sandstones, marls, platy The quarry is located in the eastern in Precambrian times, for example. limestones and sponge-dominated part of the village of Zalas, situated After that they declined, and today reef-like structures called bioherms) about 30km west of the city of Kraków they can only be seen in a few places occur in several natural and artificial and about 8km south of the town of of the world, mainly in shallow-water exposures along the whole Polish Krzeszowice (Fig. 1). This is a large, hypersaline alkaline environments. Jura Chain. They are, and used to active quarry, where the extraction of The stromatolitic layer of Zalas be, a real Mecca for professional rock mainly focuses on volcanic rocks Quarry is dated as the Late Callovian
T
4.
alas Quarry, southern Poland
Tomasz Borszcz and Dr Michał Zatoń (Poland)
and is considered to have been formed in a deeper, open shelf environment. Above the stromatolitic layer, there are pink limestones marking the beginning of the Lower Oxfordian (the first and one of the three stages of the Upper Jurassic). The bulk of the Oxfordian strata (up to the lower part of the Middle Oxfordian) exposed at Zalas Quarry is represented by both grey-bedded limestones and marls, and also spectacular huge bioherms built by sponges. It is worth noting that, currently, the architecture of the bioherms here is the best example that can be seen of such structures in the Polish Jura Chain.
A view of a part of Zalas Quarry. The Jurassic deposits (above the dotted line) overlie the Permian volcanic rocks that are the reason for the quarry’s existence. (Photo by Michał Krobicki.)
Fossils Despite a dozen visits to Zalas Quarry, it still amazes us that we still find hundreds of different types of fossil. In most cases, the fossils are very well preserved and represent a broad spectrum of marine animals that lived in the shallow, epicontinental sea that covered the area during the Middle and Late Jurassic period. The fossil creatures represent the whole trophic structure, including tiny, planktonic foraminifers and radiolarians, benthonic molluscs (gastropods and bivalves), sponges and corals, echinoderms (for example, seaurchins, sea-lilies and sea-stars), to free-swimming, nectonic animals such as belemnites, ammonites, nautiloids and those that preyed upon them – sharks and marine reptiles (these latter groups are mainly known from their fossilised teeth). Indeed, you can find all the characteristic fossils of the Jurassic that are known elsewhere from marine deposits of that age. And their abundance and variety make every trip a fruitful one! After obtaining permission to visit, you should focus first on the Middle Jurassic (Callovian) crinoidal limestones that are full of different fossils, from tiny colonial bryozoans, fragments or even nearly complete skeletons of sea urchins, ossicles of sea-lilies, large bivalves (Pholadomya), gastropods and ammonites. The latter group is represented by the characteristic
The contact between pink, Lower Oxfordian limestones and grey-bedded limestones and marls (flank bioherm facies). (Photo by Michał Krobicki.)
The highly visible contact between the Callovian hardground (the middle part of the hammer) and Lower Oxfordian pink limestones. (Photo by Michał Krobicki.)
5.
A huge Callovian ammonite, Macrocephalites. (Photo by Tomasz Brachaniec.)
A perisphinctid ammonite, Parachoffatia, from the hardground. (Photo by Michał Rakociński.)
The large bivalve, Ctenostreon from the Callovian hardground, often served as an ideal substrate for various encrusting animals. (Photo by Eligiusz Szełęg.)
A nautiloid, heavily encrusted by various sessile animals from the Callovian. (Photo by Eligiusz Szełęg.)
A close-up of the bivalve, Ctenostreon. The shell surface shows detailed impressions of some of the tiny encrusters, like various serpulid worm tubes (1) and plate-like bryozoan colonies (2).
6.
Various sea urchin spines collected from the Oxfordian marls.
and common Macrocephalites. If you are lucky, you can find crabs, which are preserved as casts of isolated carapaces or chelae. Above this section, you can find a characteristic horizon full of different fossils that are overlain by an undulating layer of stromatolites. However, the fossil horizon below the stromatolites is very interesting because it represents the so-called hardground. This represents a very slow period of sedimentation (or even a break in sedimentation) during which various shelly fossils (especially the large bivalve Ctenostreon, but also nautiloid, ammonite and other mollusc’s shells) served as a hard substrate for other different, smallsized creatures to cement to it. They include colonial bryozoans, various tubes of serpulid worms, tiny brachiopods and oysters. Because of their tiny sizes, they do not receive as much attention as larger fossils, for example, the ammonite Macrocephalites, which has a diameter of 30cm or more. However, such fossils are very interesting for palaeoecological research, because, due to cementation, they are preserved in life positions. The stromatolite layer, covering the hardground, is another interesting thing. Formed by one-celled microorganisms, they serve as a window into the microbiological world existing in a deep Jurassic sea. Over a period of many years and without any serious disturbance, lamina-by-lamina, bacteria and fungi built an extensive, wavy, carbonate structure. It is worth noting that the stromatolites from Zalas quarry represent one of the most beautiful and best developed of such structures in the Middle Jurassic deposits in Poland. Higher in the section, grey and thick, wavy structures are visible. Built by siliceous sponges of different morphologies, they form huge ‘sponge-reefs’ with a characteristic, undulating shape. Within this framework, you can also find different fossils, including brachiopods, ammonites, belemnites, fragments of sea urchins (especially their spines), sea-stars, brittlestars and sea-lilies. The first group allows us to date the bioherms as being Oxfordian in age. Originally, the sponge bioherms might have built immense organic domes in the Late Jurassic sea, harbouring a vast number of animals. Indeed,
such Oxfordian bioherms were extensive structures, ranging from Iberia in the west, to the Caucasus in the east, along the northern shelf of the Tethys Ocean. In the opinion of some experts, their origin may be related to volcanic intrusions below them, which occurred in the Cracow region. Evidence for this is the fact that Jurassic deposits in Zalas quarry directly overlay volcanic rocks. The sponges are also encrusted by tiny bryozoans and serpulids, forming the external construction of the ‘reef’.
And finally... Although the Jurassic deposits are widespread in the Polish Jura area, Zalas quarry is somewhat unique and possesses something that make us return there again and again. Not only can you find the best Jurassic stromatolites and the most spectacular sponge bioherm in the region, but you can also easily find plenty of very well-preserved fossils. The only problem is getting permission to collect as you have to get this before entering the quarry. And, once you have permission, remember that this is an active quarry and such things as safety helmets and high-visibility jackets are very important.
Further reading Matyja, B. A. & Tarkowski, R. 1981. Lower to Middle Oxfordian ammonite biostratigraphy at Zalas in the Cracow Upland, Acta Geologica Polonica, Vol. 31, No. 1 – 2: 1 – 14. Nawrocki, J., Polechońska, O., Lewandowska, A. & Werner, T. 2005. On the palaeomagnetic age of the Zalas laccolith (southern Poland). Acta Geologica Polonica, Vol. 55, No. 3: 229-236. Radwańska, U. 2005. Callovian and Oxfordian echinoids of Zalas, Volumina Jurassica, Vol. 3, s.: 63 – 74. Trammer, J. 1982. Lower to Middle Oxfordian sponges of the Polish Jura, Acta Geologica Polonica, Vol. 32, No. 1 – 2: 1 – 39. Wierzbowski, A. et al. (eds.). 2006. Jurassic of Poland and adjacent Slovakian Carpathians. Field trip guidebook of 7 th International Congress on the Jurassic System, Poland, Krakow, September 6-18, 2006.
News snippets Important finds made at Kents Cavern in Torquay A dig organised by the University of Durham, looking into why and when Neanderthals became extinct, has produced teeth and bones from late Ice Age animals, including hyenas, deer and woolly rhinos. One of the most spectacular finds was a 15,000-year-old spearpoint, known as a “sagaie”. This has been made from a reindeer antler and is thought to be the first complete one found in the UK. The teeth and bones recovered from the site are estimated to be 25,000 years old. The excavation is still going on and the team hope to make many more discoveries.
Oldest known, tree-dwelling creature 260-million-years-old The earliest evidence in the fossil record of an “opposable thumb” has been discovered showing, an evolutionary adaption that allowed animals to live in trees, away from terrestrial predators. First discovered in Russia in 1994, Suminia getmanovi has taken a long time to be formally identified. It is of late Permian age and lived 100 million years earlier than the previously firstknown, tree-dwelling mammal. Suminia was a small animal, being about 50cm tall. It had very long hands and feet, so much so, that they made up almost half the length of its four limbs. With long, slender, curved fingers, the animal was ideal for climbing and living in trees. It was also a very early ancestor of mammals.
Dutch museum “moon rock” turns out to be petrified wood At the Dutch national museum in Amsterdam, there has been on display, a special and treasured item - a piece of moon rock from the first manned lunar landing. That is, this is what was believed until recently. However, the museum curators have discovered that it is a fake and is nothing more than petrified wood. The rock was given to former Prime Minister, Willem Drees, during a tour by the three Apollo 11 astronauts, shortly after their mission in 1969. After his death, the rock was put on display at the Amsterdam museum, having been insured for £300,000. The US Space Agency (NASA) gave moon rocks to more than 100 countries following the lunar missions in the 1970s. 7.
I The diversity
of trace fossils
from the Anisian (Middle Triassic) of Winterswijk, the Netherlands Henk Oosterink (the Netherlands)
Winterswijk
8.
chnofossils are the non-body remains of organisms. This group of fossils includes burrows, borings, tracks and any other trace formed by the life activity of organisms. They are very important in determining the ecology of extinct organism – although it is not always possible to link a single ichnofossil to the organism that made it. They are also useful in palaeoenvironmental analysis and solving other sedimentary problems. As a result of finds of, for example, reptile bones, the Middle Triassic quarry of Winterswijk (Anisian) is famous for its ichnofossils of both vertebrates and invertebrates (see my article in Issue 15 of Deposits). However, also well known from this quarry are the footprints and tracks made by several Triassic reptiles. In addition, a great number of traces from invertebrates have been found there and, in this article, I will show and describe some of them.
Muschelkalk During the Muschelkalk part of the Anisian (240mya), the Central European area (Germany, Poland, Denmark, the Netherlands and north-eastern France) was a shallow sea, referred to as the Muschelkalk Sea. During this period, there were frequent regressions and transgressions and, perhaps, there were also tides. In addition, along its coastline arose abundant, so-called sabkhas (flat, coastal deserts), which were places where algae and cyanobacteria grew during high tides and floods. In this way, bio-laminates were created and, over millions of years, a thick covering of carbonate laminates developed. Eventually, these petrified into limestone. For example, the Muschelkalk sediments of Winterswijk are 50m thick and, in other parts of Central Europe, they are even thicker. During this period, the climate was dry and very hot. The Winterswijk area was situated about 25oN, so fairly near the equator. As a result of continental drift, it is now situated at about 52oN. Along the high water marks, all sorts of reptiles searched for food and it is supposed that the dead bodies of marine reptiles and fishes, which drifted ashore, were food for them (Sander & Klein 2006). Tracks and footprints of these reptiles remained in the calcareous-clay
laminates, which then hardened. In later phases, the tracks filled up with calcareous-clay and the footprints were preserved in the sediment. In this way, we now find many reptile tracks in several layers and places. In fact, Diedrich (2008) mentions 75 locations in the Central European area.
Reptile footprints and tracks In the Winterswijk quarry, five different reptile-tracks and footprints can be validly distinguished and are found in mud-cracked bio-laminates and sometimes in ripple marks. When these footprints are found, there are always two of them - positive and negative – that is, the original footprint and the cast. The footprints of Rhynchosauroides peabodyi (Faber 1958) are generally the most frequently found. Most of the time, the print of the forelimb is more deeply impressed than the hindlimb, because the weight of the reptile was on the front of its body. In fact, the fifth toe of the hindlimb has often left no impression at all and only the impression of the nail is visible. Further impressions of scales on the lower side of the feet are sometimes visible. In 2005, an excavation in the quarry by the universities of Bonn, Utrecht and Amsterdam found a Rhynchosauroides peabodyi track of about 12m. In other layers, they found trampling horizons. Other tracks are referred to as Procolophonichnium haarmuelensis (earlier called Procolophonichnium winterswijkensis, Demathieu & Oosterink 1983). These are from smaller reptiles than Rhynchosauroides peabodyi and smaller prints often mean more manus (the terminal segment of
Rhynchosauroides peabodyi (Faber 1958).
the forelimb) and pes (the terminal segment of the hindlimb) are present in one trail on the slabs. Another, much rarer track is Brachychirotherium paraparvum Demathieu & Oosterink 1988. The print of the hindlimb is about twice the size as the foreleg. Usually, the impressions of the scales and nails can also be seen. In one such track, the impression suggests that the animal slid while walking, indicating that the mud was slippery at the time. Another track that can be found is Phenacopus faberi Demathieu & Oosterink 1983. Most of the time, this is accompanied by a swinging tail-print. It looks a little bit like Procolophonichnium haarmuelensis, but good examples are rare. Finally, there is Coelurosaurichnus ratumensis Demathieu & Oosterink 1988. This has only been found once. It consists of six big prints of both manus and pes. The forelimb has five toes and the hind-leg only three, which are substantially longer and bigger.
The origin of fossil footprints. Drawing by Haubold (1984).
Procolophonichnium haarmuelensis (Demathieu & Oosterink 1983).
Brachychirotherium paraparvum (Demathieu & Oosterink 1988). Hindlimb.
Brachychirotherium paraparvum (Demathieu & Oosterink 1988). Forelimb with slide-mark.
9.
Traces of invertebrates Invertebrate-traces are divided into a number of cluster-names, representing how the traces were caused. In this way, the following classification division can be made: • Repichnia. The movement of animals over a surface leaving tracks and also worm-crawling traces, swimming traces and so on. • Fodinichnia. The feeding of deposit feeders, resulting in U-shaped, branching and sinuous burrows. • Pascichnia. The feeding of grazer. • Domichnia. A living burrow or boring. • Cubichnia. A temporary hiding or resting trace. • Fugichnia. A structure produced by an animal escaping in panic from threat. For many traces, it is impossible to work out exactly their origin, so it is not possible to classify the traces in the above groups. Therefore, it is often impossible to determine these traces by genus (ichnogenus) or species (ichnospecies) name. However, comparisons between recently made traces and fossil traces have been carried out. Brady (1947), for example, compared recent tracks of scorpions with traces in Permian Coconino sandstone in the USA.
Phenacopus faberi Demathieu & Oosterink 1983.
What about the makers?
Coelurosaurichnus ratumensis Demathieu & Oosterink 1988. Left: forelimb. Right: parts of the toes of three hindlimbs.
Whenever fossil footprints, tracks and traces are considered, it is inevitable that there will also be a discussion about the makers. However, only
Swimming traces of fishes In a layer of very fine-grained limestone, swimming trails of fishes have been discovered. These are called Undichna and are interpreted as being oscillation scratches made by the fins of a swimming fish touching the seabed. They are made up of sinusoidal waves, which were probable produced by coelacanths (oral information by Jacob Benner (Medford, USA) and Dirk Knaust (Stavanger, Norway)). These kinds of swimming traces have also been described by Simon et al (2003) as being Parundichna. This is possible, because, in the Winterswijk quarry, an almost complete coelacanth fish and also several loose scales have been found.
10.
Repichnia: cf. Parundichna Simon et al. 2003.
Repichnia: scratch marks of a reptile.
when the maker is fossilised at the end of a track, can we definitely say something about the vertebrate or invertebrate animal that made it. Unfortunately, this is extremely rare. Therefore, a link between a track-fossil and body-fossil is mostly supposition. As a result, a parataxonomic system has been established for tracks and traces. Unfortunately, this system of ichnofossil-names does not correlate with names of body-fossils. However, palaeontologists still try to link, for example, reptile-bones from the legs with reptile footprints.
Acknowledgements My thanks to Mr Arent Noordink (Aalten, the Netherlands) and Mr Martien Oosterink (Winterswijk, the Netherlands) for their help and some photos. My thanks also to Mr Jacob Benner (Medford, USA) and Mr Dirk Knaust (Stavanger, Norway) for their help in identifying some traces. The pictures are mostly from the collection of the author.
Diedrich, C. 2008. Millions of reptile tracks – Early to Middle Triassic carbonate tidal flat migration bridges of Central Europe – reptile immigration into the Germanic Basin. Palaeogeography, Palaeoclimatology, Palaeoecology 259: 410 – 423. Haubold, H. 1984. Saurierfährten. Die Neue Brehm-Bücherei. A. ������������������� Ziemsen Verlag, Wittenberg Lutherstadt. Oosterink, H.W. 2008. Triassic reptiles from the Lower Muschelkalk of Winterswijk. Deposits 15: 34 – 38. Sander, P.M. & N. Klein. 2006. Terrestrial reptile tracks and marine reptile body fossils from the Lower Muschelkalk (Middle Triassic) of Winterswijk, The Netherlands. Journal of Vertebrate Paleontology 26, 3 Abstracts 119A. Simon, Th., H. Hagdorn, M.K. Hagdorn & A. Seilacher. 2003. Swimming trace of a coelacanth fish from the Lower Keuper of South-West Germany. Palaeontology 46, 5: 911 – 926. www.geo.arizona.edu.
Fodinichnia: Radulichnus isp. Marks probably made by snails. Oral information from Dirk Knaust.
Cubichnia of insects or lobsters (genus and species indeterminate). Oral information from Dirk Knaust.
References Brady, L.F. 1947. Invertebrate tracks from the Coconino sandstone of Northern Arizona. Journal of Paleontology 21, 5: 466 – 472. Bromley, R.G. 1990. Trace fossils. Biology and taphonomy. Unwin Hyman Ltd, London. Demathieu, G.R. & H.W. Oosterink. 1983. Die Wirbeltier-Ichnofauna aus dem Unteren Muschelkalk von Winterswijk. Die ���� Reptilienfährten aus der Mitteltrias der Niederlande. Staringia 7. Ned.Geol.Ver. Demathieu, G.R. & H.W. Oosterink. 1988. New discoveries of ichnofossils from the Middle Triassic of Winterswijk (the Netherlands). Geologie en Mijnbouw 67: 3 – 17.
Mud cracks with structures made by algae.
Repichnia: worm-crawling traces.
Fodinichnia: Rhizocorallium jenense Zenker 1836.
11.
This fossil: the dinosaur relic Rob Hope (France)
A
break from work, and also from reading about the history of palaeontology, enabled me to get away for a while. And a chance visit to the south of England found me driving through the Sussex town of Lewes. Held up by a red light, I suddenly realised - didn’t Gideon Algernon Mantell once live here? I parked the car and set off to visit this charming town. In particular, I wanted to find the house where Mantell had actually worked and lived. When I eventually found it, there was a large blue plaque on the wall confirming it to be the home of the ‘discoverer of the Iguanodon’ (Fig. 1). This animal was discovered in 1822, which was a fascinating period and one about which I have read a lot recently. Perhaps too much, for I more-than-half expected the doctor himself to step outside, dressed in Victorian garb, to shake my hand: “Ah, Rob, I have been expecting you… but aren’t you rather late?” “Yes indeed, but I have been working rather too much lately!” Mantell’s cabinet of curiosities was vast. Many of his fossils (which were later sold to the British Museum) were held in this very house, before being moved to a new home in nearby Brighton in 1833. His hunting ground for fossil remnants were mostly the nearby, grand Cretaceous chalk quarries, and also the sandstones of Tilgate Forest (from the Wealden Formation). I ventured to investigate (and eventually found) the landscape where, according to legend, Mantell’s wife, Ann, had
Fig. 1. Outside Mantell’s home.
12.
picked up a large fossil tooth, almost 190 years ago. Gideon Mantell sought desperately to identify the unusual fossil, requesting aid from William Buckland and even the French anatomist, Baron Cuvier… But to no avail. Several years later, a chance meeting in the Hunterian Museum with naturalist, S Stutchbury, solved Mantell’s frustrating enigma. For all the world, the fossil seemed like a giant iguana tooth. Could Mantell be, along with Buckland (who had just found and named Megalosaurus), one of the first to discover and interpret some kind of huge ‘lizard’ fossil? It was indeed to be the case. In 1825, Gideon Mantell published a paper describing Iguanodon. And so many years before even the comparative anatomist, Richard Owen, from London’s Natural History Museum, had named a new group of ancient animals as “Dinosauria” (see, for example, ‘The Isle of Wight dinosaurs’ by Dr S Sweetman in Issue 19 of Deposits). The Iguanodon was to become a modern icon of British palaeontology. My chance visit through the land of Gideon Mantell also took me to the Booth Natural History Museum, in Brighton (Fig. 2). Here, in a secluded corner of this fascinating museum, are several Iguanodon fossils from the South Downs area. Sadly, it is unclear whether these remarkable specimens were once part of the Mantell collection. However, tantalisingly, all of the musty and faded tickets glued to each fossil had descriptive
Fig. 2. Booth Natural History Museum, Brighton.
writings seemingly in the distinctive 19th century mode of handwriting. Had this small group of Iguanodon fossils been actually found by Gideon Mantell? I could just make out the wording on one of the tickets as ‘a cast’. So maybe these were, in fact, copies of his fossils? I wanted to find out and, like the great man himself who had urgently sought to identify his first dinosaur specimen, here I was, seeking to identify the history of these fossils and, indeed, to whom these fossils had once belonged. I enquired at the entrance of the building, but the curator of the museum was, just like me, away on holiday! All of those fossils were remarkable, but one stood out - the ‘thumb spike’ (Fig. 3). Was this (or the cast of it) the very fossil that had inspired Owen, when he was preparing lifesize dinosaur replicas for London’s Great Exhibition of 1851? He placed the ‘spike’ on the Iguanodon nose, as a horn, and not on the hand as a thumb, as was later shown to be the case. (Initially, just one fossil ‘spike’ had been found and it was not articulated.) Perhaps yes… perhaps no. This fossil remains, nevertheless, remarkable. Will there be a sequel to this story? Maybe, but it doesn’t matter. It’s good to have a break sometimes, to simply get away and have an opportunity to actually see the areas and fossils we so often only read about.
Fig. 3. This fossil... Is it Mantell’s?
Location profile: Seasalter, Kent Joe Shimmin (UK)
T
he huge expanse of London Clay (from the Eocene) exposed on Seasalter’s foreshore lends the location a bleak atmosphere. It is not the most picturesque of fossil hunting sites but, occasionally, stunning phosphatic fossils are found. Perseverance is rewarded here.
Geology and collecting
Directions
To find fossils, you have to descend to the pebble beach and make your way onto the foreshore. The majority of fossils found here are locked up in phosphatic nodules, but, unfortunately, can resemble other, different rocks in which you find no fossils. To further complicate things, the phosphatic nodules will also often have black stains on them from the breakdown of marine life, which can look exactly like part of a crustacean showing through. A typical, crab-containing phosphatic nodule will be rounded, with two lobes where the pincers are concealed. The nodule will be of a creamy colour, not orange, like broken cement stones. It will not be angular in any place and will not be too thick. Once you have found a good nodule, it is literally worth holding onto it as a reference while you get your eye in. It has to be stressed that, the nodules are not easy to prepare, and you cannot simply break them open in the hope of finding a decent specimen inside. What you will find is the parts of the fossils sticking out of the nodule. You can then prepare the nodule to reveal more of the fossil inside. The nodules can be found in any area where there are accumulations of pyrite and other rocks.
From Whitstable, follow the signs to Seasalter. From the A290, you will find yourself driving along Joy Lane. After about 800m, look for a turning on your right over a single carriageway railway bridge. If you get to the shops, you have gone too far. Go over the bridge and turn immediately left onto Admiralty Walk. After a few tens of metres, there is a lay-by where you can park. From the parking area, walk back the way you drove in and take a left down to the beach opposite the railway bridge.
Responsible collecting Deposits Magazine and UK Fossils stress the importance of sensible and safe collecting. We have a national code of conduct, which can be found on the UK Fossils website: http://www. ukfossils.co.uk/ncc.htm. Please limit your activities to collecting only a few nodules and DO NOT take more than you need. It is important that localities are preserved for future generations to study and enjoy, otherwise many of our present popular locations will be destroyed and we may never know their true scientific importance. Fossils can be collected for a couple of hours either side of low tide and there is no chance of getting cut off. Watch out for deep holes made by bait diggers and subsequently filled in with loose sand – these can be spotted by the large number of worm casts on their surfaces. You will get muddy at Seasalter; wellies are highly recommended!
Nipa palm fruit.
Always follow our national collecting code, and always check tides!
Seasalter
Kent
www.ukfossils.co.uk/ncc.htm
PROFILE INFORMATION
Location type Coastal location
Geology London Clay (Eocene)
Find frequency Good, but fossils are found in phosphatic nodules that require skilled preparation
Accessibility Fairly easy
Most common finds Crabs, fish, fruit and fossil wood Partially exposed Portunites sp. crab in nodule.
Piece of fish skull.
For more information - visit: www.seasalter.ukfossils.co.uk UK Fos
sils
Est. 1998
Network
Our rating
Seasalter is featured on our web site. The UK Fossils Network is an extensive portal featuring locations from all over the UK for collecting fossils. Information on the geology, along with collecting tips, further reading and much more can be found here.
13.
Fossil sea urchins as hard substrates Stephen K Donovan (the Netherlands) and John WM Jagt (the Netherlands)
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fossil is a mine of information about just one specimen of one species and many such specimens represent extinct species. Consequently, no observations of the living organism are possible - everything we know about that species will have to be gleaned from fossils. Morphology (the form or shape of an organism or part of it) is obviously a starting point - that is, what are the features of the specimen? Describing a specimen may be laborious, but it provides a factual basis for all later determinations and speculation. And it is only when a specimen’s morphology is fully understood that its evolutionary relationship to other organisms can be confidently worked out. Is it a species that is already well known or a rare specimen? Or is it a new species? Astute geologists will make further observations and deductions. If he or she collected the specimen, then it should be supported by information concerning the stratigraphy, sedimentology, and associated animals and plants in the area. What do these many strands of evidence say about the environment and ecology of the specimen and species? In addition, what does the morphology of the specimen suggest about how the fossil functioned as a living organism? Many fossil organisms are comparable to living organisms, for example, interpretation of Chalk (Late Cretaceous) Micraster can benefit from what we know about living heart urchins. Therefore, we can build up a collection of facts about our specimen’s form, classification, environment and function. The next step may be more problematic. How did the fossil interact with other organisms when it was alive? Without direct evidence, we are left only with uniformitarian arguments (that is, arguments that assume that the present is a key to understanding the past), although the older the fossil, the more speculative such an interpretation may have to be. What makes these interpretations of ancient organic interactions more valid is those relatively rare examples in which the evidence is
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actually preserved. To return to the examples of Upper Cretaceous irregular echinoids (for example, the Micraster mentioned above), one line of evidence is provided by examples in which the fossil tests (a ‘test’ is the shell of the sea urchin) retain the skeletons of encrusting organisms, such as oysters, cementing brachiopods and bryozoans. Of course, care must be taken to determine if such infestation occurred before or after the death of the echinoid, but there are various lines of evidence that can be used and some are discussed below. However, what happens if these hard parts are not retained or the infesting organism lacked any? In
particular, how can the evidence of boring, biting and embedding trace fossils on an echinoid test provide evidence of an ancient ecology? In brief, different types of trace fossil data can provide different evidence for reactions between the organisms that lived together. In this article, we will discuss some examples from our own research in northern Europe.
(1) Echinocorys from northern France Echinoids that are perforated by small round holes or bearing pits, or both (assignable to the ichnotaxon Oichnus), are rare and enigmatic fossils. Circular drill holes that
Fig. 1. Echinocorys scutata Leske (Oertijdmuseum de Groene Poort, Boxtel, The Netherlands, specimen MAB 003183), with two pits of Oichnus cf. excavatus Donovan & Jagt, from upper Turonian/Coniacian chalk between Ault and Onival, Somme, northern France (after Donovan & Jagt, 2005, fig. 1). a, Oblique anterior view of test, interambulacrum central. Pits in ambulacrum to right; flint nodule left. Scale bar represents 10mm. b, Enlargement of pits. Scale bar represents 5mm. c, Detail of larger pit. Scale in mm.
perforate the test are commonly considered to be the result of predatory or parasitic activity by certain groups of gastropods. It is more difficult to determine the function of circular pits on the surface of the echinoid test (morphologically Oichnus), but which are obviously not the result of predation. In Fig. 1, there is a specimen of the common, Late Cretaceous, holasteroid echinoid, Echinocorys scutata, which bears two Oichnus pits that invite palaeoecological consideration. On this echinoid, there are small, shallow, circular, non-penetrative pits, which are situated in adjacent columns in an ambulacrum, that is, a radially arranged band, together with its underlying structure, through which the double rows of tube feet (tentacle-like extensions of the water vascular system) protrude. People who research drill holes or pits are divided into two groups those that name their small round holes or pits and those that do not! We agree with the fundamental idea of systematic ichnology (that is, the study of trace fossils – see, for example, the article by Henk Oosterink in this issue). This is succinctly defined by Pickerill (1994, p. 15), such that: “... the labelling of ichnotaxa provides a necessary vocabulary for writing and conversing about trace fossils.” Therefore, it is important to this article to assign our round pits to the appropriate ichnotaxon; that is, a taxon – or a unit of one or more organisms - based on the fossilised work of an organism, for example, a burrow, boring or footprint. The circular pits described above are included in Oichnus excavatus (Donovan & Jagt), but only with some hesitation. This particular trace fossil is usually deeper and more prominent. However, the main interest in these holes rests in the palaeoecology of their producers. Small round holes in the tests of fossil echinoids present problems of interpretation, the most obvious questions being who did it and why? The specimen of E. scutata shown in Fig. 1 provides an example of distinctive behaviour of such pitforming organisms. The two
shallow, non-penetrative pits are close together and each is precisely located. Such a precise location strongly suggests that the echinoid was alive when it was infested by the pit-forming organisms, although there is no indication (such as obvious deformity of the growth of the test) to support this. The pits may represent examples of predation that has been disturbed or, more probably, could represent the traces of one or two organisms that hitched a ride on the test for protection, or to gain a feeding or respiratory advantage. In this respect, their position may indicate a preference by the pit-forming organism for the front end of the echinoid. The pit-forming organism was probably filter feeding and, by attaching itself in this position, automatically gained elevation and the correct orientation for feeding, as well as the protection provided by the surrounding tube feet and spines. However, the identity of the pit-forming organism remains unknown.
(2) Punctured Hemipneustes The holasteroid echinoid, Hemipneustes striatoradiatus (Leske), is a large and striking part
of the invertebrate macrofauna of the type Maastrichtian (Upper Cretaceous) of Limburg and Liège in the Netherlands and Belgium. Live and dead tests of this taxon provided hard substrates for infestation by a variety of encrusting and pitforming organisms. Evidence of the interactions of organisms provided by H. striatoradiatus substrates includes borings, encrustation by shelly invertebrates and marks of predation. However, while the unusual specimen discussed below (Fig. 2) is distinctive, it is uncertain if it is caused by a large invertebrate or is an example of a deep puncture made by a predatory marine vertebrate and subsequently repaired by the echinoid. In fact, the pit has an unusual morphology, unlike any other trace fossil found in these common echinoids. The test of this H. striatoradiatus is well preserved apart from a few cracks probably arising after deposition. The size, position and morphology of the pit on the centre of the oral (lower) surface, lying on the midline between the mouth and anus are all unusual (Fig. 2). The pit is lined with small tubercles (that is, the bases of spines), demonstrating that, whatever sort of infestation it represents, it was not lethal, because the echinoid was
Fig. 2. Puncture hole in Hemipneustes striatoradiatus (Leske) (Natuurhistorisch Museum Maastricht, specimen NHMM 2007 035), from the upper Maastrichtian Nekum Member, Maastricht Formation, southern Limburg, the Netherlands (after Donovan et al., 2008, fig. 1). A, Hole in the oral surface, in the mid-line and just posterior of centre; the plane of symmetry of the wound is oriented left-to-right at about mid-height of the figure. Anterior of echinoid towards top of figure. B, C, Latex cast. B, Latex cast of pit in plan view, anterior towards top of page. Note the larger and smaller hollows, particularly apparent to the upper left, representing external moulds of primary (large) and secondary tubercles (small). C, Lateral view from the upper left in (B).
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able to repair itself. The pit is large, close in size to Oichnus excavatus, but it is not quite the same and is situated on the ‘wrong’ part of the test. With only rare exceptions, O. excavatus is found on the aboral (upper) surface and such a welldeveloped specimen is unknown from such a central position on the adoral surface (that is, the lower surface, in contact with the sediment surface in life and bearing the mouth). The pit is also more deeply impressed than an attachment scar of, for example, a foraminiferan living on the sea floor. Intuitively, the position of the pit seems to have been a poor one for a large, filterfeeding, invertebrate-infesting organism that was ‘hitching a ride’ on a live, furrowing, echinoid living on the sea floor. (Compare this with the previous example.)
The trace described above is a deep indentation on an area of the test that commonly was not available for infestation by invertebrates during the life of the echinoid. The position and morphology of this trace lead us to think that it may have been caused by a vertebrate, rather than an invertebrate, and possibly represents a scar of a lessthan-lethal predatory attack. That is, the wound healed after the attack and the evidence was preserved as a pit. This is supported by it being of similar diameter to other traces in the same species that we also think were produced by vertebrates. Fossil vertebrates known from the type-area of the Maastrichtian included mosasaurs, elasmosaurid plesiosaurs, turtles, a crocodile, dinosaurs and various fishes. The pit could have been made by a vertebrate
Fig. 3. Elongate pentagonal trace fossil (basal attachment scar) on the test of Echinocorys gr. conoidea (Goldfuss) (NHMM 2009 005, from the upper Lixhe 1 Member (Gulpen Formation; lower upper Maastrichtian), province of Liège, northeast Belgium (after Donovan et al. 2010, fig. 2). Scale in mm.
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with rounded, well-separated teeth, because this is the only penetrative wound in the test. The distance from the circumference of the perforation to the closest parts of the external edge of the echinoid is about 30mm. The tooth may have been pointed or blunt, evidence for the former being disguised by the echinoid, which seem to have sealed the base by growing new test over it. Two, teardrop-shaped indentations on the aboral surface may have been produced by two teeth of the other jaw failing to gain purchase and slipping across the surface. Based on these observations and deductions, the most probable culprits were a mosasaur or a bony fish - the tooth was conical, but may have been truncated, perhaps due to having been broken.
(3) A five-sided attachment scar Tests of large Late Cretaceous holasteroid echinoid genera, such as Echinocorys Leske and Hemipneustes L Agassiz, do not usually preserve growth reactions to attacks from settling, cementing or boring invertebrates, or lesions caused by vertebrates, which occurred during the life of the echinoid. However, there may be subtle evidence that such infestations occurred during life. Infestations not associated with modifications of the test are interpreted as having occurred, most probably, after death, but before the final burial of the echinoid test. The trace fossil shown in Fig. 3 is from a test of Echinocorys gr. conoidea (Goldfuss). Although the test is slightly fractured and possibly lightly crushed, this has not altered the morphology of the large trace fossil, which is non-penetrative. There is also no evidence of the echinoid reacting to this infestation with any unusual form of growth. This trace fossil is unlikely to be a healed puncture, on account of the complex morphology of the margins, with the folded areas inside the circumference. We think it is the result of an unmineralized, sessile (that is, non-mobile) invertebrate embedding itself (only to a shallow extent) into the echinoid while it was still alive. This idea is supported by the presence of numerous tubercles (that is, attachment points for
spines) within the area of the trace, suggesting that spines probably regenerated after the death of the trace maker. The position of the trace close to the centre of the widest part of adjoining ambulacrum would have placed the maker near the maximum distance possible from any tube feet, but above the sediment surface. Bald areas of test around the trace may be the result of cleaning by the trace maker. We prefer the idea that this trace is a scar produced by something like a sea anemone. The shape of the trace might have been normal for the producing species, but it may also be due to a response to its environment. For example, the producing organism may be elongated by gravity, having attached itself to an overly steep surface. Alternatively, if the organism was harvesting plankton from currents flowing past the test, then a more elongated form may have been a successful feeding strategy.
Acknowledgements We are indebted to Phil Crabb (Photographic Unit, The Natural History Museum, London), who provided all of the images for this article.
References Donovan, S.K. & Jagt, J.W.M. 2005. Site selectivity of pits in the Chalk (Upper Cretaceous) echinoid Echinocorys Leske from France. Bulletin of the Mizunami Fossil Museum 31 (for 2004): 21-24. Donovan, S.K., Jagt, J.W.M. & Dols, P.P.M.A. 2010 (in press). Ichnology of Late Cretaceous echinoids from the Maastrichtian type area (The Netherlands, Belgium) – 2. A pentagonal attachment scar on Echinocorys gr. conoidea (Goldfuss). Bulletin of the Mizunami Fossil Museum 36. Donovan, S.K., Jagt, J.W.M. & Lewis, D.N. 2008. Ichnology of Late Cretaceous echinoids from the Maastrichtian type area (The Netherlands, Belgium) - 1. A healed puncture wound in Hemipneustes striatoradiatus (Leske). Bulletin of the Mizunami Fossil Museum 34: 73-76. Pickerill, R.K. 1994. Nomenclature and taxonomy of invertebrate trace fossils. In: Donovan, S.K. (ed.) The Palaeobiology of Trace Fossils, 3-42. John Wiley and Sons, Chichester.
Sands of Gobi Desert yield new species of nut-cracking dinosaur Steve Koppes (USA) Plants or meat - that’s about all that fossils ever tell palaeontologists about a dinosaur’s diet. However, the skull characteristics of a new species of parrot-beaked dinosaur and its associated gizzard stones indicate that the animal fed on nuts and/or seeds. These characteristics present the first solid evidence of nut-eating in any dinosaur. “The parallels in the skull to that in parrots, the descendants of dinosaurs most famous for their nut-cracking habits, are remarkable,” said Paul Sereno, a palaeontologist at the University of Chicago and National Geographic Explorer-in-Residence. Sereno, and two colleagues from the People’s Republic of China, announced their discovery on 17 June 2008 in the Proceedings of the Royal Society B. The palaeontologists discovered the new dinosaur, which they have named Psittacosaurus gobiensis, in the Gobi Desert of Inner Mongolia in 2001, and spent years preparing and studying the specimen. The dinosaur is approximately 110 million years old, dating from the mid-Cretaceous. The quantity and size of gizzard stones in birds correlates with dietary preference. Larger, more numerous gizzard stones point to a diet of harder food, such as nuts and seeds. “The psittacosaur at hand has a huge pile of stomach stones, more than 50, to grind away at whatever it eats, and this is totally out of proportion to its threefoot body length,” Sereno explained. Technically speaking, the dinosaur is also important because it displays a whole new way of chewing, which Sereno and co-authors have dubbed
Artistic rendering of a newly discovered species of parrot-beaked dinosaur, Psittacosaurus gobiensis. Scientists first discovered psittacosaurs in the Gobi Desert in 1922, calling them “parrot-beaked” for their resemblance to parrots. Psittacosaurs evolved their strong-jawed, nut-eating habits 60 million years before the earliest parrot. Art Credit: Todd Marshall.
“inclined-angle” chewing. “The jaws are drawn backward and upward instead of just closing or moving fore and aft,” Sereno said. “It remains to be seen whether some other planteating dinosaurs or other reptiles had the same mechanism.” The unusual chewing style has solved a major mystery regarding the wear patterns on psittacosaur teeth. Psittacosaurs sported rigid skulls, but their teeth show the same sliding wear patterns as plant-eating dinosaurs with flexible skulls.
Further reading “A new psittacosaur from Inner Mongolia and the parrot-like structure and function of the psittacosaur skull,” Paul C. Sereno, University of Chicago; Zhao Xijin, Chinese Academy of Sciences; Tan Lin, Bureau of Land Resources, Hohot, People’s Republic of China, Proceedings of the Royal Society B, June 17, 2009.
Skull of the parrot-beaked dinosaur, Psittacosaurus gobiensis, next to that of a living macaw. Research on the dinosaur was funded by the National Geographic Society, David and Lucile Packard Foundation, Biological Sciences Division, University of Chicago and the Long Hao Institute of Stratigraphic Paleontology. Photo Credit: Mike Hettwer.
17.
M
ineral classics from Wales
18.
Tom Cotterell (UK)
A
sk any mineral collector to name a classic mineral locality or region in Britain and they will probably think of Cornwall or Devon, perhaps Weardale in Co Durham, or even the Caldbeck Fells or the West Cumbrian iron mining district in Cumbria - but probably not Wales. This is not to say that Wales has no classic minerals, but is perhaps a reflection of collecting habits and the preference for large, brightly coloured crystals. Wales has a long history of mining dating back to, at least, the Bronze Age, but, unlike some other regions, there does not appear to have been a desire by miners to extract mineral specimens for sale. Indeed, a network of mineral dealers, as was clearly present in Cornwall during the nineteenth and twentieth centuries, was totally absent in Wales. One factor is that the establishment of a National Museum in Wales occurred relatively late (in 1907) and did not open to the general public until the 1920s. Before this, there was no central repository for specimens collected in Wales and, consequently, mineral collections with historical significance are rare in the Principality. The university colleges founded during the 1870s and 1880s built up their own academic collections. Earlier still, the Royal Institute of South Wales (founded in Swansea in 1835), established geological collections, but its focus appears (from what records remain) to have been wide ranging and not specific to Wales. Therefore, during the heyday of mining in Wales, the lack of one overall institution focussing on the mineralogy of Wales appears to have resulted in a dearth of specimens being preserved.
Fig. 1. Sulphate of lead (anglesite) figured by Sowerby (1806).
Fig. 2. Brookite. Tabular crystal 20mm across from Fron Oleu, Prenteg. NMW 75.38G.M.1. Photo MP Cooper © Amgueddfa Cymru.
Some historic Welsh material exists in older collections based in England, for example, the Natural History Museum in London, but, compared with other British mining regions, the number and quality of specimens is limited. Since its foundation, the National Museum of Wales has, acquired a number of private and academic collections containing oldtime Welsh mineral specimens. This has clearly helped our understanding of Welsh mineralogy. Unfortunately, as with many old collections, provenance details are often vague or entirely absent.
What is a classic mineral? In general, some experience is required to appreciate the minerals that occur in the Principality. In addition, to assess which Welsh minerals are ‘classics’, we must first decide what actually constitutes a ‘classic mineral’. Is it merely a case of something that is very old or maybe something of exceptional beauty? Perhaps, it could be a particular association or assemblage of minerals characteristic to a locality. A classic mineral is difficult to define and different collectors may have different opinions. The most important factor is surely aesthetics. Attractive minerals are popular and remembered more than rare minerals that may be ugly. However, size is also important. Larger crystals get noticed more than smaller equivalents and, if a particular mineral represents the largest example ever discovered, it will certainly feature as a classic. Type locality specimens, or those from the original locality of discovery for a species, are considered important and may also be termed ‘classics’. So
to are minerals of particular cultural significance. In these cases, being attractive is not a prerequisite to being a ‘classic’. The age of a specimen, or when it was discovered, quite often affects a collector’s opinion. Those minerals of historical significance often get described as ‘classics’, even though (physically) they may be no different to another discovered more recently. Clearly, a large number of minerals will fall into one of these categories, but the real classics are those that satisfy several of these criteria. For the purposes of this article, a selection of classic minerals from Wales is described chronologically and not necessarily in order of importance.
Old time classics Anglesite was first discovered at Parys Mountain, near Amlwch on Anglesey, during the late 18th Century (Monnet, 1779). However, for many years, it was described by its chemistry as “vitriol de plombe” or “sulphate of lead”. According to one early account, it was “found in great quantity” (Withering, 1783). However, it was not until 1832 that François Sulpice Beudant proposed the name ‘anglesite’, after the island of Anglesey, a name that has been used ever since. The majority of specimens were collected before Beudant’s description and, consequently, many specimens in older museum collections still bear labels containing the earlier, chemical-based names. Sowerby (1806) produced one of the earliest pictures of anglesite in Volume 2 of his British Mineralogy publication (Fig. 1). The accuracy of Sowerby’s hand coloured plates is staggering when compared with modern photography.
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Fig. 3. Hair pyrites (millerite) from Wales figured by Sowerby (1809).
Anglesite from Parys Mountain is not a particularly attractive mineral and crystals rarely exceed 1cm in length. However, specimens from this, the type locality, are much sought after and remain ‘classics’ to this day. The mineral brookite is an iconic Welsh mineral. Fine crystals are figured in many mineralogical publications. “Oxide of titanium”, as it was known during the early 19th Century, was figured by James Sowerby in 1809 in Volume 3 of his British Mineralogy publication. At the time, the location was given as “near Snowdon”, but his son, George Brettingham Sowerby, later (in 1838) more specifically described it as “on the road side between Beddgelert and Tremaddoc,
Fig. 4. Millerite. Acicular crystal spray 42mm across with baryte in clay ironstone from Treharris, Glamorgan. NMW 52.385.GR.4. Photo TF Cotterell © Amgueddfa Cymru.
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Carnarvonshire, about 8 miles from Snowdon”. The specimen figured by Sowerby (1809) was not especially attractive, but collecting at the site in later years produced what are considered to be some of the finest examples of this species (Fig. 2). Unfortunately, the delicate nature of these crystals and the high value of good examples led to a number of mineral dealers fabricating specimens by gluing detached crystals onto similar looking matrix. The name ‘brookite’ was proposed by M Lévy in 1825 in honour of the British crystallographer and mineralogist, Henry James Brooke (1771 to 1857). Recent discoveries in Pakistan and Madagascar have surpassed Welsh brookite specimens in terms of crystal size and abundance, but the classic status of the Welsh material is likely. Another old-time classic is the nickel sulphide mineral, millerite, from the South Wales Coalfield. Sowerby (1809) figured a specimen in Volume 3 of British Mineralogy (Fig. 3) in argillaceous ironstone from “Wales”. At that time, it was believed to be a peculiar variety of pyrite, named “hair pyrites” on account of its appearance. Research by Professor William Hallowes Miller of Cambridge University showed this to be sulphuret of nickel (nickel sulphide) (Miller, 1842). In 1845, Wilhelm Haidinger named the species ‘millerite’ in honour of the professor. Millerite, from the South Wales Coalfield, occasionally produces stunning display specimens (Fig. 4). The best crystal sprays are attractive and, at up to 54mm across, are very large for the species and are as good as from anywhere in the world. Surprisingly, beyond our shores, very
Fig. 5. Quartz. 11cm tall crystal from Votty & Bowydd, Blaenau Ffestiniog. NMW 27.111. GR.140, ex GJ Williams collection. Photo DI Green © Amgueddfa Cymru.
Fig. 6. Leaf gold with sphalerite and quartz from Gwynfynydd mine, Dolgellau. Specimen measures 40mm x 20mm. NMW 72.33G.M.7. Photo MP Cooper © Amgueddfa Cymru.
few people are aware of its presence in Wales. There is patchy evidence to suggest that, during Victorian times, a trade in quartz crystals developed in Snowdonia. Unfortunately, little is recorded and the validity of some specimens labelled as from “Snowdon” or “Snowdonia” is questionable. Quartz is a very common mineral, but some of the finest crystals from Britain have been obtained in the neighbourhood of Snowdon (Rudler, 1905). Occasionally, fine crystals are encountered in the slate quarries in Snowdonia or during the construction of forestry tracks. The crystal shown in Fig. 5 is one of the largest known from this area and was collected during the late 19th Century. The most culturally significant mineral from Wales is gold. Welsh gold holds a special place in people’s minds because of its links to the Royal family, who traditionally use Welsh gold in their wedding rings. Gold from Wales tends to be valued much higher (up to three times more) than standard gold, although, technically, the gold is no richer than that from any other country. Specimens of Welsh gold in matrix are especially sought after and command high prices.
During the later part of the 19th century, a gold rush occurred around Dolgellau in north Wales. The rush was caused by the announcement by Arthur Dean, in 1845, that he had discovered gold at Cwmheisian lead mine. This was followed by claims from others that they had also discovered gold in the area in 1836. Whatever the truth, it is really irrelevant. What is important is that it led to the discovery of the largest gold producing area in the British Isles. However, despite the deposits being exceptionally rich, the ore bodies were small and sporadic in nature. Therefore, they were quickly exhausted leading to a ‘boom and bust’ situation. Gold is found in two distinct mineral assemblages in the Dolgellau area. The two major gold mines, Clogau St David’s and Gwynfynydd, are each typified by a distinctive assemblage. At Clogau, gold frequently occurs in association with silvery bismuth tellurides in quartz, while, at Gwynfynydd, gold is usually disseminated throughout sphalerite in quartz (Fig. 6). During the late 19th and early 20th centuries, one person stands apart from anyone else in terms of collecting Welsh minerals. Griffith John, or ‘GJ’ as he preferred to be known, was a keen amateur geologist and widely regarded as an expert on north Wales geology. A teacher by training, GJ spent most of his life teaching in Ffestiniog, but was appointed to the post of Assistant Inspector for Metalliferous Mines and Quarries for the North Wales and Ireland Division under Dr Clement le Neve Foster in 1895. This position spurred on his interest in mineralogy, allowing him to collect specimens from all of the mines he visited. He collected with Arthur Ian Edward Montague Russell (later Sir) and made a number of new discoveries. His collection was acquired by the National Museum of Wales in 1927. Many of his specimens are classics owing to the fact that no one else collected from some of the sites he visited. One of GJ Williams’ most important discoveries was the barium feldspars, celsian (Fig. 7) and paracelsian (Fig. 8) at the Benallt manganese mine on Pen Llŷn. His specimens, collected in 1911, remain the finest crystallized examples of both species.
Fig. 7. Celsian. Manebach-Baveno fourling, 10mm on edge, from Benallt mine, Pen Llŷn. NMW 27.111.GR.381. ex GJ Williams collection. Photo MP Cooper © Amgueddfa Cymru.
Fig. 8. Paracelsian. Prismatic crystals up to 25mm in length from Benallt mine, Pen Llŷn. NMW 27.111.GR.387, ex GJ Williams collection. Photo MP Cooper © Amgueddfa Cymru.
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Fig. 9. Cymrite. Scanning electron micrograph of a sheaf-like crystal aggregate from Benallt mine, Pen Llŷn. NMW 2006.15G.M.2h. Image MP Lambert/TF Cotterell, © Amgueddfa Cymru.
Following the discovery of these two minerals, interest in the mineralogy of Benallt manganese mine grew. Researchers at the British Museum (Natural History) led by Walter Campbell Smith, studied the complicated mineralogy of the deposit. The chief geologist to the Iron and Steel Control of the Ministry of Supply, Dr Arthur William Groves, was primed to keep an eye open for any interesting looking minerals from the mine when it reopened after the onset of the Second World War. This resulted in the discovery of several mineral species new to science.
The rarest of these new minerals, hydrated barium feldspar, was named cymrite after the Welsh name for Wales, ‘Cymru’ (Fig. 9). It forms two different habits of crystal, both of which have recently been rediscovered on specimens from the mine dumps remaining at the site. The naming of this mineral after the country of its discovery, Wales, makes this a classic to people from Wales, but, more importantly, this is a very rare mineral worldwide and to find crystals is even more unusual.
Modern classics The modern age of mineral collecting began during the 1960s with active exploration by collectors and with the advent of micromineralogy. One of the major finds in Wales was the discovery of coarsely crystallized pyromorphite (Fig. 10) underground in Bwlch-glas mine, near Tal-y-bont, in north Ceredigion. The richest specimens are without question the finest examples of this mineral from Wales and the very best are comparable to classic specimens from the Caldbeck Fells and Cornwall. Some of the earlier samples were
Fig. 10. Pyromorphite. Grass-green prismatic crystals on quartz from Bwlch-glas mine. Specimen 10cm tall. Collected c. 1972. BR Moore collection. Photo MP Cooper © Amgueddfa Cymru.
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Fig. 11. Calcite. 22cm tall scalenohedral crystal from Taff’s Well Quarry, near Cardiff. R Sutcliffe collection. Photo MP Cooper © Amgueddfa Cymru.
sold by mineral dealers as from Plynlimon, the highest hill in the area. Unfortunately, specimens were then relabelled as from Plynlimon Mine resulting in confusion over the exact source. Plynlimon mine has never produced specimen-quality pyromorphite. In South Wales, the southern outcrop of Carboniferous Limestone has long been known to produce large calcite crystals (Fig. 11) of varying forms. However, it was not until the 1970s that the increasingly large quarries start to produce exceptional specimens. The enormous Taff’s Well Quarry, which has hollowed out Little Garth Hill, is the locality that most people have heard of. From the 1920s to the 1970s, it was known as Walnut Tree Quarry, then Steetley Quarry after the name of the operating company. The largest calcite crystals are known to exceed 30cm in length. In general, the larger the crystal, the more overgrowth there is and the uglier they become. However, for sheer size these calcites are British classics. Across much of Wales, the legacy of mining has left its mark in the form of mine tips, derelict buildings and surface scars, such as opencast workings and mine shafts. Underground, secondary post-mining minerals continue to form on the sides of old mine tunnels where chemical reactions are taking place caused by the introduction of oxygen from the atmosphere through these man-made voids. Flowstones containing base metals are particularly prominent. During the early 1980s, a new hydrated zinc copper sulphate
Fig. 12. Namuwite. Pale blue microcrystalline crust. Specimen 6cm across. NMW 27.111.GR.414, ex GJ Williams collection. © Amgueddfa Cymru.
hydroxide mineral was identified by researchers at the National Museum of Wales on post-mining flowstone that had been collected many years earlier by GJ Williams underground in Aberllyn mine, near Betws-y-coed. This mineral was named namuwite (Fig. 12) after the National Museum of Wales, where the specimen is housed. The naming of minerals after companies or institutions is now considered inappropriate making this species very unusual. Only one specimen from the type locality is known, although this mineral has since been discovered at a number of mines in mid-Wales. Post-mining secondary minerals also form inside mine tips, caused by the decay of base metal-bearing sulphides exposed to rainwater and the atmosphere. Many of these complex Pb-Zn-Cu bearing minerals are brightly coloured. The Central Wales Orefield plays host to a huge range of secondary, predominantly post-mining, mineral species. In a number of cases, examples of minerals found in mine tips are far better than any discovered at other localities worldwide, albeit still only as millimetre-sized crystals! Classic examples include the world’s finest bechererite (Fig. 13), ramsbeckite (Fig. 14) and redgillite (Fig. 15). New discoveries continue to be made. Although active mining in Wales has ceased, in recent years, quarrying operations have revealed a few rare
and bizarre looking minerals. At Dolyhir Quarry in the Welsh borders, superb microcrystals of the hydrated rare earth-bearing barium calcium carbonate, ewaldite (Fig. 16), have been found in some abundance. Inevitably, there will be some minerals that collectors feel have been omitted. However, part of any assessment involves personal preference. For a slightly different view on Welsh mineral classics, it may be worth consulting King, RJ (1991). For further information on Welsh minerals, look at the Mineralogy of Wales website at: http://www. museumwales.ac.uk/en/mineralogy_ of_wales/. This site provides up-todate descriptions of all of the minerals that are known to occur in Wales and new findings or information can also be posted to the site. In part, the site is based on an earlier publication by Bevins, RE (1994).
Fig. 13. Bechererite. Crystal sprays to 1.3mm across from Esgairhir mine. SA Rust collection. Photo SA Rust © SA Rust.
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Further reading Bevins, R.E. (1994). A Mineralogy of Wales. 146pp. National Museum of Wales, Geological Series No. 16, Cardiff. Dean, A. (1845). Notice on the discovery of gold ores in Merionethshire, North Wales. Report of the British Association for the Advancement of Science (for 1844), 56. Haidinger, W. (1845). Handbuch der bestimmenden Mineralogie. Vienna. King, R.J. (1991), Minerals explained 14: Some Welsh mineral classics. Geology Today, 145148. Monnet, A.G. (1779). Nouveau Systême de Minéralogie. Paris. Rudler, F.W. (1905). A handbook to a collection of the Minerals of the British Isles, mostly selected from the Ludlam collection, in the Museum of Practical Geology, Jermyn Street, London, S.W. 241 pp. Sowerby, G.B. (1838). Locality for brookite. Annals and Magazine of Natural History, series 2, 2, 293. Sowerby, J. (1806). British Mineralogy: or coloured figures intended to elucidate the mineralogy of Great Britain. Vol. 2. 199 pp. Sowerby, J. (1809). British Mineralogy: or coloured figures intended to elucidate the mineralogy of Great Britain. Vol. 3. 209 pp. Withering W. (1783). Outlines of Mineralogy.
Fig. 16. Ewaldite. Scanning electron micrograph of pyramidal ewaldite crystal surrounded by core-bit twinned prismatic harmotome crystals. Dolyhir Quarry. NMW 2007.22G.M.16. Image MP Lambert/TF Cotterell © Amgueddfa Cymru.
Fig. 15. Redgillite. Feathery redgillite crystal spray 1mm tall from Eaglebrook mine. JS Mason collection. Photo DI Green © Amgueddfa Cymru.
Mineral focus... Redgillite
Fig. 14. Ramsbeckite. Emerald green crystals to 1.5mm across from Penrhiw mine, Ponterwyd. JS Mason collection. Photo DI Green © Amgueddfa Cymru.
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Redgillite is found only in a few European countries, the most common localities being the UK and Germany. In the UK, the mineral can be found in England, Scotland and Wales, and was first discovered (and approved as being an official mineral by the International Mineralogical Association) in Cumbria. In particular, it was first noticed at Red Gill Mine in the Caldbeck Fells, but was described based on material from the nearby Silver Gill where it occurs more abundantly. In the UK, it occurs more frequently in Wales than anywhere else, but other European countries where it is found include Ireland and Italy. Redgillite is a copper sulphate that is visually similar to malachite. Chemically, it is very similar to montetrisaite (a mineral found in Italy and Bolivia). The mineral consists of bladed crystals and in Wales, they can reach up to 1mm long. It is found in thin fractures in party oxidised copper sulphides and can be pale green, grass green, emerald green or nickel green in colour. It is transparent and translucent, and has a vitreous lustre.
Climate events let ice age mammoths go far below 40°N Dick Mol (Netherlands) and Ralf-Dietrich Kahlke (Germany)
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he remains of four mammoth bulls have been discovered in southern Spain. They lived about 30 to 40 thousand years ago near Padul, a small city in today’s Granada. These are Europe’s most southerly skeletal remains of Mammuthus primigenius and were unearthed in a moor on the 37°N latitude. This is considerably further south of the inhospitable habitat that one usually imagines for mammoths and for the characteristically dry and cold climate that prevailed during the ice ages in northern Eurasia. “These woolly mammoth finds do not belong to stray animals that only chanced to head south, but belonged to Granada’s permanent inhabitants at this time”, says Diego Álvarez-Lao, from the University of Oviedo. Dick Mol, ice age expert at the Natural History Museum of Rotterdam and frequent contributor to this magazine, adds: “Nevertheless, the Spanish mammoths have not differed anatomically from their congeners in more northern regions.” Climate and environmental data show that it was not the longing for summer temperatures or the chirp of crickets that lured the ice age giants to the south, but a diet of grass, various herbs and shrubs! The expansion of the mammoth steppe with its typical vegetation allowed the wandering of the giants and other ice age animals below the 40°N latitude and far to the south. Nuria García, from the University Complutense de Madrid explains, “Fossil plants, which have been found in drill cores from scientific drilling in Spain and the nearby Mediterranean Sea, as well as our investigations of the Padul sediments, indicate that the animals lived on the plants of the mammoth steppe.” One of the discoverers of these remains is Senckenberg scientist, Ralf-Dietrich Kahlke, who focused on the reasons that Mammuthus primigenius passed below 40°N. As he says, “A comparison with other sites between the 38°N and 36°N latitude shows that the animals pushed south, 30 to 40 thousand years ago also in areas outside of Europe”. Therefore, the southern-most sites of the ice age giants lie on a belt, which stretches
from Western Europe via Georgia, the Siberian Baikal region to eastern China, and from Korea to the Midwest of America. Nevertheless, the dispersal of the giants was occasionally blocked. The impressively high Sierra Nevada at Padul formed a natural barrier, likewise, the Rocky Mountains in North America. Other obstacles were areas that did not offer suitable food, such as desert-like regions or the Great Plains of North America, which expanded because of a vegetation change. The southerly push of Mammuthus primigenius in Europe and their migration to southern Spain and Italy happened at the same time as similar advances into eastern China, to the north of Japan and to Kamchatka. This phenomenon may be related to coupled climate events in the northeast Atlantic and the north-west Pacific. Dr. Kahlke concludes, “This is proof that global mechanisms, which regulated climate already during the ice age, also influenced vegetation and, with it, also animal migration”.
Mammuthus primigenius. Painting by K. K. Flerov (Reconstruction) © Senckenberg Research Institutes.
Peat layers at the Padul site (Granada, Spain) © Senckenberg Research Institutes.
References Álvarez-Lao, D., Kahlke, R.D., García, N. & Mol, D., 2009: “The Padul mammoth finds - On the southernmost record of Mammuthus primigenius in Europe and its southern spread during the Late Pleistocene” is published in: Palaeogeography, Palaeoclimatology, Palaeoecology, 278: 57-70.
Peat layers at the Padul site (Granada, Spain) © Senckenberg Research Institutes.
Almost complete lower jaw of a male woolly mammoth from Padul (Granada, southern Spain) © Senckenberg Research Institutes.
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Deciphering carpoids:
F
ossils can provide unique insights into the history of life on Earth, which stretches back nearly four billion years. Unfortunately, the closest living relatives of fossil organisms are sometimes unclear and, therefore, their evolutionary significance may not (yet) have been fully realised. Such fossils are called ‘problematica’ – the bizarre-looking carpoids are a classic example of a problematic fossil group. Carpoids are small, f lattened, marine fossils, ranging from a few millimetres to a few centimetres in length. They possess a hard, mineralized skeleton composed of calcium carbonate (calcite) and often display one or more slender appendages (arms, stems or tails). The group existed during the Palaeozoic Era, from the Middle Cambrian (about 510mya) to the Late Carboniferous (about 310mya), and its fossils are found today in marine rocks throughout the world. Within the UK, carpoids are known
from County Tyrone (Northern Ireland), Ayrshire (Scotland), the West Midlands (England) and South Wales. The first carpoid fossils were reported in the late 1850s, when the palaeontologists Joachim Barrande and Elkanah Billings described material from Bohemia and Canada, respectively. Subsequent discoveries in the mid-to-late nineteenth century, and especially in the twentieth, greatly increased the known diversity of the group, and there are now over 180 recognised species div ided into four sub-groups (cinctans, ctenocystoids, solutes and stylophorans). However, despite over 150 years of study, carpoids continue to defy palaeontologists’ best efforts to make sense of them.
stylophorans are characterised by an asymmetrical body (or theca) and a long, tripartite appendage. The appendage is the focal point of many debates. It is envisaged as a feeding arm or a muscular, locomotory tail. If it is taken as an arm, then the mouth must have been located nearby, defining this end as the front of the animal. Alternatively, if the appendage is interpreted as a tail, then the mouth
Stylophorans No group more clearly exemplifies the controversy surrounding carpoids than the stylophorans. First discovered in 1858 by Billings,
Fig. 2. Anatifopsis barrandei, a stylophoran carpoid from the Ordovician of Bohemia.
Fig. 1. Ceratocystis sp., a stylophoran carpoid from the Cambrian of Spain.
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Fig. 3. Anomalocystites cornutus, a stylophoran carpoid from the Devonian of New York, USA.
fossil ‘problematica’ was presumably located at the opposite margin of the animal and the appendage marked the rear end. Consequently, it is unclear which end is the front and which the back in stylophorans, a fundamental issue for palaeontologists! The disagreement does not stop here though. Some stylophorans exhibit an arc-like series of special body openings that have been considered to be gill slits, that is, structures which aid feeding and/or respiration in several groups of modern marine animals, including fish. This interpretation is important, as it offers a guide to the biological affinities of stylophorans, as well as their mode of life. However, it is not accepted by all scientists. The only way to conf idently address these problematic points is to consider the sof t par ts (that is, muscles, ligaments and internal organs) of the animals. Alas, the hard calcite skeleton is all that remains in carpoid fossils. As a result, most reconstructions of their internal anatomy are highly speculative and difficult to justify.
Fig. 4. Rhenocystis latipedunculata, a stylophoran carpoid from the Devonian of Germany.
Evolutionary position Because of their cryptic morphology (epitomized by stylophorans), carpoids are hard to classify and there is heated discussion over their placement in the animal evolutionary tree. It is widely accepted that they are deuterostomes – a major animal group that includes chordates (vertebrates, sea squirts and lancelets), hemichordates (acorn worms and sea angels) and echinoderms (starfish, sea urchins and the like). However, determining the relationships of carpoids with other deuterostomes has proven controversial - originally regarded as primitive echinoderms, carpoids have subsequently been reinterpreted as ‘advanced’ (derived) echinoderms closely related to sea lilies, and even as primitive chordates and hemichordates. Discriminating between these radically different theories is essential to accurately reconstruct the early evolution of animals.
Dr Imran A Rahman (UK)
– variants of medical CT scanners – have been used to ‘see’ inside fossils, revealing structures that appear to support the idea that stylophorans possessed gill slits. Moreover, by examining the genes of modern animals and the microscopic structure of fossils, it was possible to determine that the skeleton of carpoids is identical to that of echinoderms, implying that carpoids are echinoderms. Nevertheless, while computational and molecular methods may provide valuable insights into the enigmatic carpoids, new fossils remain key to unlocking their mysteries. Discovering such specimens requires not only a great deal of luck, but also the assistance of fossil collectors worldwide – I entreat you all to get hunting!
Further reading Rahman, I.A. 2009. Making sense of carpoids. Geology Today 25: 34–38.
Solving the enigma A critical step towards understanding the evolutionary history of life is to decipher all of the fossils - including ‘problematica’ - that document this period. The carpoid fossil record is difficult to read. However, there are signs that, by employing sophisticated new analytical techniques, it may be possible to resolve some of the issues surrounding this notorious extinct group. For example, X-ray micro-CT systems
Fig. 5. Plasiacystis sp., a solute carpoid from the Ordovician of Morocco.
Fig. 6. Protocinctus mansillaensis, a cinctan carpoid from the Cambrian of Spain.
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Recent finds:
your finds from the summer holidays
Rob found this brachiopod in the Ironbridge Gorge in August. Jonathan sent us some photos of this ammonite that he dug up in July, from a newly ploughed field near his home in camerton, Banes. It is about 37cm wide.
Nick found his biggest ammonite from the bottom of an old slide/slip near Stonebarrow in Dorset. The find was made after heavy rain had unearthed the top 10cm. He found it on the 14 August 2009. The ammonite is of the Liparoceras genus, and has a diameter of nearly 24cm.
Lynne & Charles found this excellent belemnite at Port Mulgrave in May.
This partial fish was found in July by E MacQuarrie, who found it at Achanarras Quarry, Spittal, among Caithness flagstones. In July, Fiona found this lovely Rhizodont cleithrum fish bone in Scotland.
Allan sent us this photo of an Androgynoceras ammonite he found in late June from Seatown in Dorset, while on a guided tour.
Adrian found this Speeton ammonite, “Simbirskites” in early August. Anne found this partial dinosaur tooth in August. It was found at Yaverland, Isle of Wight. The Dinosuar Isle museum identified it as a Spinosaur, of the Baryonyx genus. She tells us “I can’t tell you how chuffed I am at this little gem”.
Andrew found this lovely Heterodontus shark tooth from Eastchurch Gap and The Leas in August.
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This pseudolioceras lythense ammonite was found between Whitby and Saltwick nab by Brad Fawcett in August.
A lovely Echinocorys scutata echinoid found in September by Robert in the Harwich Haven Estuary.
Andrew also found these Pachygaleus shark teeth from Minster Leas in July.
Two ammonites from Port Mulgrave found by H Jennings.
Your field reports Speeton - Gary in August I noticed lots of Devil’s Toenails on the foreshore. Heavy rains had brought down quite a lot of the clay from the cliffs containing hundreds of very small ammonites and pieces of Aegocrioceras. John found this ammonite in a nodule at Whitby in August.
Keeley found this Beaniceras ammonite at Bay Ness in July. The fossil was prepped by Andy in Germany.
Janet found several of these Brittle Stars in the Oxford Clay, Cotswold Water Park in July. She contacted the Natural History Museum, who has told her, it is a new species!
This snake vertebre was found by Andrew at Warden Point in July.
In addition to the new species above, Janet, also found this crab at the same time!
Charles found these fossils in the shingle bank at Redcar in August.
Jurassic5 found these plant fossils from Saltwick Bay in September.
This echinoid was found in flint in September, near Overstrand in Norfolk by Jiminij.
We had a forum member post this photo, of what they thought was a “Reptile head”, but is actually a coral. Another member commented “I see what you mean about its initial appearance! You don’t have to shut one eye and squint the other to see it should be the head of a reptile”
Seatown - Phil Frost in August I have had a keen interest in fossils since childhood and have just returned from my holiday in Devon with my family. I have been to this area many times and have visited the usual fossil haunts in Dorset - Lyme Regis and Charmouth, but it was through your site that I was introduced to Seatown. This place is worth a visit just for the pub grub and the beach, but a trip along the cliffs with a guide allowed us to collect some great ammonites and belemnites, along with a little fool’s gold. It was one of the most memorable days of our holiday - thanks to the information you provided on your website. Lyme Regis - Pete G in August I’ve just come back from a very enjoyable couple of days at Lyme Regis. We got onto the beach at Church cliffs/Black Ven at 1pm, but the beach was littered in glass and silt from the huge fall at Church Cliffs, which occurred last year in May. Black Ven slips were a little more productive, but still quite silted over. I found a piece of shark fin spine about 30mm long, a nice (but small) paddle digit, and a very small fragment of lobster tail from the Cretaceous Greensand/ Gault Clay, which had found its way onto the beach. Unfortunately, we did not find a single pyrite ammonite, which was unusual. I did find a nice lump of Lias, which I split to reveal two nice Promsicroceras and a Cymbites. On Thursday, we went to the Charmouth end of the cliffs along Stonebarrow Cliffs. We found many pyrite ammonites and a nice phragmacone, along with a couple of tiny gastropods. However, that was about it for Charmouth - not too good at all - but, it was a nice walk soaking up the sun on a beautiful day. So that was it for Lyme and Charmouth - quite silted over and very over collected (we visited just after the summer holidays), but a very enjoyable trip to one of my favourite places. Definitely worth a visit.
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Collecting rocks and minerals: a recollection Malcolm Chapman (UK)
C
ollecting is natural. We all do it to a greater or lesser degree and what we collect is motivated by many factors including value and the appeal to the eye. Rarity is often a factor, as is cost, and interest can be awoken by someone you are related to, a teacher or a friend. So how did I become involved with collecting rocks and minerals? It was a television programme called Serendipity, which was broadcast about 35 years ago. Not long before (and at great cost), I bought some amber jewellery. And, then, there on the TV, was a young lady walking along the beach at Aldeburgh and picking up stones - not many, considering the number surrounding her, but a few handfuls. She was collecting amber and she had gathered an admirable collection for free, which would have made most people envious. The grey matter started working. Aldeburgh was some distance away, but, close at hand, was the beach at Sheerness and I knew about longshore drift... By the action of wind and tide, stones on the east coast work their way south and north-facing beaches, like Sheerness, gather the stones moving from north of that point. Therefore, I decided that amber should be on Sheerness beach. I had never studied the stones on a beach before, but I believed that there could be many glamorous stones that I could find such that I envisioned making jewellery with them, mostly pendants. My experience was that they came in many colours and were often worn into the right shape and size. Of course, the problem was that they were damp when I found them and showed their colour beautifully when on the beach. However, when dry, they lost their brilliance. Therefore, it was time for study and I began to
learn about tumbling stones and then making jewellery. I put these ideas together and then I had to learn marketing. That came easy at first as I sold them at the office, but eventually that market dried up. So, in the end, I put them up for auction and they sold at values so high I couldn’t believe it. My mind had started wandering. Those stones had spent hundreds, perhaps thousands of years, being tossed around in the sea. Yet, they could be made to look so beautiful. So, what about the original stones before I or the sea had worked on them? They must have looked better still. It seemed a good idea to seek them out to see how good they actually were. Logically, as my stones had come from the east coast, that seemed the place to start looking. So, I started collecting books, but none referred to this area. In fact, there seemed to be a total lack of east coast locations of any importance. However, one book referred to Devon and Cornwall and the wealth of resources to be found within their boundaries. And it named locations and the stones that could be collected (although, at that time, they meant little to me as I lived on the east coast). These places were a long way away. Fortunately, I owned a camper van so I could park anywhere overnight. So, as a first expedition, I planned 20 locations to visit over a week. However, there were problems - some sites would not allow access, some could not be found and some had been flattened and covered with soil. However, there were a number of places that could be located and also some I came across that had not been planned. It is said that if a child catches a fish first time he or she goes fishing, they are hooked for life. The same might be said of rock collecting!
The photos are examples of how magnification can expose new minerals in a sample. However, because of their small size, identification is restricted to visual clues. Have a go at identifying these samples and let us have your opinion.
That first journey, over 30 years, ago contained moments that have remained with ever me since. The first piece of quartz crystal I found came from north of Dartmoor: Cligga Head produced a quartz and cuprite combination that was of an excellent quality. I also found various crystals in the St Just/Bottalock area. In fact, it was here that I came across two men who collected crystals from the walls of mines, including torbenite, which was very radioactive, as I found when testing the piece they kindly gave me. I began to make a point of collecting anything that caught my eye. I knew I would have a lot of time to study them after I got home. However, the last port of call on that seminal journey was disappointing. I found a site with lots of crystals and was about to start collecting when I was thrown out. A member of staff employed by English China Clay ejected me for my own safety, although I could see no danger. That location is now visited by millions of people: they have put some strange domes there (and a lot of plants) and another great collecting site was gone! I am not criticising EEC. In fact, it employees were magnificent in their attitude. When I was next in Cornwall, being the type of person I am, I decided to complain in person at their head office about being ejected. I gave no notice of my visit. I made my complaints and was about to leave when I was invited into the office. There, a man asked someone to collect together some bits and pieces and, while we waited, he explained their safety rules, which were very simple - no one could be on any site without a company representative. They had a system whereby they allocated retired members of staff to accompany visitors. As they had lost some of these people recently, he could not allocate anyone at that time. They then presented me with a box of minerals, including a large piece of turquoise and a stone set in plastic. Later, he allocated me to Maurice Grigg. The name may mean as little to you now as it did to me then. However, just tap it in to your Google search and you will begin to get some idea of the importance of the man. He had the best collection of Cornish minerals and rocks outside museums and they were all self-collected. His rejects, which lay in his garden, would have been regarded elsewhere as a great collection. He had worked for ECC all
his life and had collected over many years. It is difficult to name the best thing in his collection, but, for me, it was his collection of morion (black quartz). It comprised large pieces of crystals as good as I have ever seen. Maurice knew all the places to go for scarce and rare minerals. For example ‘miner’s eggs’ are rare crystals of kaolinite found in china clay. They are not great to look at, but very valuable. He took me to where they could be easily found. In fact, tourmaline rocks were easy to find when Maurice was there. He regularly found specimens that were recognised as being the only examples found in Cornwall or even Britain. Maurice gave access to many people to absolutely dream locations. In this respect, many well-known geologists hold Maurice in high regard and can tell many lovely anecdotes about the man. Sadly, Maurice died in 1997. He will be remembered by many people and he was my teacher. My research provided me with many more locations to visit including (and especially) Wanlockhead in Scotland. My collection now comprises thousands of items of British origin. Maurice convinced me that I should not buy foreign items and, mostly, I have respected that idea. However, I have bought Arkansas quartz to sell on and have kept some good specimens. Otherwise, there are only about half a dozen items I have not found myself. Unfortunately, it is now impossible for me to go collecting due to ill health, so I have taken up a new hobby. I have got into micro collecting. Actually, that is not true. You see, I have been into micro collecting since the beginning, only I didn’t realise it. My new collection consists of the rocks that I have already collected because they looked unusual. Under magnification, they display the characteristics that drew my attention in the first place. Now, they provide their own mystery as they have to be identified. Depth of focus is a problem when photographing, but some are quite good. There are a few examples illustrating this article with no identification to give an example of the craft. But, at the end of the day, this is a hobby (or career) that can occupy a lifetime. Everyday, every location, every find is different. It is to be highly recommended. But, I suspect, you already know that!
Book review Excursion guide to the geology of East Sutherland and Caithness The Caithness area of Scotland is important for its geology, but is also well known for its palaeontology. The Caithness Flagstones are famous for fossil fish and the Helmsdale Fault is famous for the Helmsdale Boulder Beds deposited beside an active submarine fault scarp. The area even once had its own ‘gold rush’ and you can still try your luck at panning there today at Kildonan! The area is also popular with the oil industry as an onshore analogue for several offshore oilfield reservoirs. This book provides excellent locality excursions to all of these sites, covering the Devonian Old Red Sandstone, with its world-famous, fossil fish faunas and the Jurassic rocks along the coast from Helmsdale to Golspie, including the famous fossil coral reef. In addition to the locations, the authors provide an overview of the geology of East Sutherland and Caithness. This guide updates 1993 edition and includes new material. It is copiously illustrated with colour photographs and diagrams. Both authors, Nigel Trewin and Andrew Hurst, are professors of geology at Aberdeen University and have published many research papers on the geology and fossils of the area. They have also led many field excursions to the area for university classes, the oil industry and for geological societies. For anyone interested in geology and visiting this area of Scotland, the book is very useful particularly because, for a long time, it has been out of print and there have been no such guides to the area. Now, once again, this superb book is your geological guide to the area. Price: £14.95 (Softback) UKGE Code: BK1750 ISBN: 9781906716011 Published by: Dunedin Academic Press Ltd
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Geological field trip through Scotland: basalts from the Isle of Skye Dr Robert Sturm (Austria) The Isle of Skye is a part of the Inner Hebrides in the north-west of Scotland. It has a total area of 174,000ha and has an irregularly shaped coastline that is typical of the British Isles. Since the early 19th century, the island has become a centre of geological research, because rocks of different geological periods are exposed there. For instance, the gneisses of the Lewisian complex were formed in the Proterizoicum, 2,800mya and, therefore, are some of the oldest rocks in Europe. On the other hand, intrusive and extrusive igneous rocks can be assigned to magmatic events that covered wide parts of the island during the Tertiary. This event, which took place about 60mya, resulted in the development of the Atlantic Ocean in its present form. In more recent times, two ice ages, which affected the island 26,000 years ago (the Dimlington glacial) and 11,000 years ago (the Loch Lomond glacial), resulted in the formation of a partly spectacular glacigen landscape (a landscape formed by the ice) with sediments that are of high interest for geological research. Impressive evidence for the Tertiary volcanism is provided by the plateau
lava series (these are horizontally stacked layers of lava), mainly exposed in the north and west of the island. These extrusive rock formations probably reached a thickness of 1,200m before they were subject to significant erosion. The main part of the lavas can be classified as basalts, that is, dark igneous rocks with a low content of silicon dioxide (SiO2) and enhanced concentrations of iron oxide (FeO) and magnesium oxide (MgO). Only the uppermost layers of the lava series exhibit a more acidic (that is, granitic) chemistry with higher contents of SiO2 and, therefore, may be categorised as trachytes. In the centre of the plateau lava series, massive extrusive rocks can be found. However, the upper and lower parts of this impressive lithology are characterised by amygdaloidal basalts (Fig. 2). It is these that I will concentrate on in the rest of this article.
Amygdaloidal basalts from the Old Man of Storr As shown in Fig. 2, amygdaloidal basalts are marked by bulbous cavities that were formed by the escape of gas
Fig. 1. Geological map of the Isle of Skye (modified after Anderson & Dunham 1966) illustrating the high variability of rocks that can be found on the island.
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during the fast crystallisation of the rock. These cavities were subsequently filled with minerals, which had crystallised from mineral solutions permeating through the extrusive igneous rocks. A well-known sampling site, where such amygdaloidal basalts can be found, is in the area around the Old Man of Storr in the northeast of Skye. This is a basalt obelisk, 30m high, that was chiefly formed by wind erosion and is recognisable from afar as a remarkable element of the rough landscape. The geodes of the basalts found around the Old Man of Storr are filled with a wide range of minerals, including calcite (CaCO3), chlorite, quartz (SiO2), gyrolite, as well as a high number of zeolite species (for example, analcime, natrolite, chabasite, heulandites, laumontite, stilbite, thomsonite, mesolite and garronite).
Fig. 2. Amygdaloidal basalts sampled in the area around t 2 shows a cavity filled with the fibrous zeolite natrolite, w depicts a geode partly filled by the cubic zeolite chabasite
Preparation of the basalts for light-microscopy To give some insight into the amygdaloidal basalt geodes and to learn something about their formation and the arrangement of the different minerals, you need to produce petrographic thin sections and to study them under the lightmicroscope. I produced thin sections of geodes filled with various minerals using a standard procedure. To start with, small blocks with a base area of 2 x 4cm and containing impressive bubbles and cavities were cut out of the sample rocks and mounted with their lower sides on glass slides using a 2-component-resin (for example, Köropax 439). Subsequently, the blocks were ground from the other side, using silicon-carbide (SiO) powders with different grain sizes. The polishing was continued until the blocks reached a thickness of about 35µm, being the optimum thickness for petrographic thin
the Old Man of Storr in the north-east of Skye. Image whereas image 4 exhibits a calcite geode and image 5 e.
sections used for bright and darkfield microscopy. After finishing the polishing procedure, the preparations were covered with a layer of Canada balsam and a thin cover of glass. The microscopic examination of the sections and photography of selected geodes were carried out using an appropriately equipped microscope (Nikon, model SE-S-B).
What can be observed under the microscope? Representative results obtained from the microscopic work are summarised in Figs. 5 to 7. As exhibited by the different images,
the shape of the geodes found in the amygdaloidal basalt is subject to remarkable variations, ranging from drop-like over lentiform to spherical. Those geodes being characterised by drop-like or spherical shapes were commonly formed in a non-f lowing lava, while elongated, ellipsoidal cavities preferentially developed during lava flow, whereby the longer axes of the cavities are often oriented parallel to the original f low direction. Some geodes, above all those with numerous mineral components, represent valuable indicators for various geological problems (for example, determination of original orientations of rock formations).
Fig. 3. Impressions of the landscape on the Isle of Skye, which was formed during Tertiary volcanism and the two ice ages that affected the island 26,000 and 11,000 years ago.
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Monomineralic geodes such as that illustrated in figure 6, are chief ly filled with calcite, such that the visualisation of the grain boundaries is only possible in the dark-field using crossed polarisators. Due to the different orientation of single crystals, a typical pattern of undulatory (that is, speckled) extinction may be recognised under the microscope. The development of such calcite geodes required an extensive permeation of the former gas bubbles by a fluid enriched in CO2 and calcium. Both constituents remained in rather high amounts after cr ystallisation of the lava (note that the rock chemistry is mainly characterised by the elements magnesium and iron) and, therefore, could be dissolved in a f luid phase. Within the hydrothermal temperature range
(300°C to 150°C) the crystallisation of calcite grains reached a maximum. Silicatic geodes are furthermore characterised by a predominance of numerous kinds of minerals, with the number of contained mineral phases varying between 3 and 8. Under the microscope, preferentially occurring minerals are, besides several species of zeolite (analcime, stilbite, chabasite and natrolite), different varieties of quartz and, above all, chalcedon. The crystallisation of silicates takes place in a similar way as that of carbonates: After crystallisation of the extrusive igneous rock, which may be classified as poor in silicon (see above), excess amounts of the element and other basaltincompatible elements (calcium and sodium) were dissolved in a f luid. Mineral formation within
Fig. 4. Single steps for the production of petrographic thin sections: a) the sample block is fixed onto a glass slide, b) the sample block is ground and polished, c) the section is covered with Canada balsam and a glass cover.
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available cavities was a rather complex process, because it took place according to a temperaturecontrolled temporary sequence, which becomes clearly visible by the mineral zonation (Image 1 in Fig. 7). Zeolite crystallization starts at temperatures of about 220°C with the high-temperature phase laumontite (CaAl 2Si 4O12 x 4 H2O). Continuous decline of the temperature and silicate concentration in the fluid phase causes the development of the phyllo-zeolites heulandite ((Ca0,5 ,Na,K)Al 3Si9 O24 x 7-8 H2O) and stilbite (NaCa 4 Al8Si 28O 72 x 30 H2O). At the final stage of crystallization (
