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Geomodels in engineering: An introduction

Peter Fookes, Geoff Pettifer and Tony Waltham (UK) This article is based on the introduction to the newly published book Geomodels in Engineering Geology – An Introduction. What, why and when? The Earth is an active planet in a constant state of change. These changes can take place over both long and short periods of geological time (thousands or millions of years) or much more quickly on an engineering timescale (minutes, hours or days). Geological processes continually modify the Earth’s surface, destroying old rocks, creating new ones and adding to the complexity of ground conditions: the so-called ‘geological cycle’. The all-important concept that drives this geological plate tectonics. The benefits geologists bring to construction projects must exceed the cost of their services — that is, they must accurately improve the engineer’s ground knowledge more cheaply and effectively than any other method. They must reduce the risk of geological hazards by anticipating situations perhaps unseen by the engineers and also help to determine effective ways of dealing with risks and any problems arising during design and construction. The main role of the engineer geologist is to interpret the geology and ground correctly. Creating an initial model for the geology of the site is an excellent start. Geology (the study of the Earth) and its closest geo-relative, geomorphology (the study of the Earth’s surface), are concerned with changes over time and any geomodel has to build in any changes likely to occur in the near future, especially when the construction project may … Read More

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Duria Antiquior: A nineteenth-century forerunner of palaeoart

Steven Wade Veatch (USA) Fig. 1. Duria Antiquior. A watercolour painted in 1830 by Henry De la Beche, who conjured up a vivid picture of an ancient world. It is now in the National Museum of Wales and another copy can be seen at the Sedgwick Museum in Cambridge. (Image is public domain.) In a breath of inspiration in 1830, English geologist, Henry De la Beche (1796–1855), while exploring new intellectual territories in the emerging fields of palaeontology, painted Duria Antiquior (meaning “a more ancient Dorset”), a representation of a prehistoric Dorset coast. De la Beche’s work was ground breaking – his artwork combined science and art in the first artistic rendering of a paleontological scene, while laying bare the secrets of the past. Before 1830, art depicting the prehistoric world did not exist and these realms were unknown to the public (Porter, n.d.). While it is true that scientists made drawings of fossil animals and exchanged them with each other in private letters, the public had no concept of how prehistoric animals looked. This painting opened people’s imagination to new visions, thoughts and beliefs. De la Beche’s painting also laid the foundation for a new genre that would later be known as palaeoart, an artistic genre that reconstructs prehistoric life according to the fossil record, scientific understanding and artistic imagination. De la Bache’s brushstrokes of prehistoric time included (literally) all the information known at that time about ancient life and soon became the first teaching graphic used in the … Read More

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Concretions in sandstones of the Inner Hebrides, Scotland

Mark Wilkinson (UK) Concretions are a common feature in many sedimentary rocks, yet they seem sometimes to be misunderstood. So, how do concretions form? As well-studied examples, let’s look at the ones found in some of the sandstones of the Scottish Inner Hebrides, notably the islands of Eigg and Skye. The concretions are found in several formations, but perhaps the largest and most spectacular are in the Valtos Sandstone Formation of the Great Estuarine Group. This was originally named the Concretionary Sandstone Series after the prominent metre-scale concretions. It is Bathonian in age (Middle Jurassic) and is interpreted as having been deposited in a coastal environment. The Great Estuarine Group is becoming famous for its abundant dinosaur footprints and much rarer skeletal material. The concretions themselves vary from spherical to elongate volumes of rock and are typically from around 50cm to one metre or more in diameter. They are also often coalesced into groups (Fig. 1). Inside the concretions, the spaces between the sand grains are filled completely with a calcite cement. The concretions are resistant to weathering compared to the host sandstone, which is fairly soft, so stick out from the cliff in a sometimes rather alarming manner as you walk below them. I’ve been visiting the concretions sporadically for around 30 years and some of the ones that I photographed in the cliffs in the 1980s are now lying loose on the beach. None of them have fallen while I’ve been there, touch wood. Fig 1. Concretions on … Read More

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Disappearing Dunwich

Roy Bullard (UK) There are many places around the coastline of the British Isles that are quite simply majestic and, in their own unique ways, full of magic. Dunwich lies between the lovely town of Southwold and the village of Sizewell on the East Coast of England in the county of Suffolk. It is a coastal area that is easy to include in this category and is a place that I love to visit. However, as you sit there on the shore watching the cliffs and the North Sea, it is hard to imagine that so much has been lost since the time when Dunwich was once a large, thriving community. Fig. 1. Sandy cliffs of Dunwich. My aim in this short article is to take a look at the present state of this coastline and compare it with the coast as it once was before huge amounts of coastal erosion had taken place. In addition, I will take a look at the area’s history and mention, in passing, one of its well-worked, mythical tales. A steeply sloping shingle beach now lies in front of the cliffs at Dunwich. These cliffs have changed a lot over time but, over the past few years, erosion has decreased substantially. The cliffs today are overgrown and this indicates a significant slowdown in the rate of erosion. However, with the ongoing threat of climate change and rising sea levels, the local residents and council have joined together to act now to protect the northern … Read More

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Book review: Geology of the South Devon Coast from the Dorset County boundary to the Brixham area: Geologists’ Association Guide No 73, by John CW Cope

Jon Trevelyan (UK) This is the second Geologists’ Association (GA) guide by Professor John Cope to be published in the last two years. The first was the second edition of his excellent Dorset guide, which was reviewed in the last issue of Deposits. And, on the grounds that “if it … Read More

Northern Rocks: Shetland

Neville Martin (UK) Shetland is famous for many things including ponies, knitwear, sheep and sheepdogs, birdlife and fishing. It is less well known for being an excellent attraction for the geologist or that it is currently going through the process of qualifying for European and World Geopark recognition. The rocks of Shetland are too old for fossils with the exception of some fish and aquatic plant fossils at the southern and western extremities. However, what it lacks in fossils it more than makes up for in an abundant variety of minerals and geological structures and, while looking for minerals, the geologist can enjoy some of the most spectacular seascape in the UK. In addition, the islands have a long history of mineral extraction and there has been talk of possible, future platinum and gold mining. Fig. 1. Old Red Sandstone Cliffs, Bard Bressay and Noss. One of the reasons for the geological diversity is that the Great Glen Fault, which formed Loch Ness, also manifests itself in Shetland. This gives rise to a displacement of some 60 to 80km, such that there is a distinct difference between East and West Shetland. The landscape is also the result of sculpturing by glaciers and the sea. The many submerged, glacial valleys are called “voes”, the largest of which is Sullom Voe, the site of the oil terminal where oil from north, east and west of Shetland is landed. The shelter provided by such a large voe (which is sea loch) made it … Read More

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Extinction of the mammoth and the Clathrate Gun

Joanne Ballard and André Bijkerk (USA) In this article, we will argue that the extinction of megafauna on the mammoth steppes of the Northern Hemisphere may ultimately have been caused by the release of massive quantities of methane in the North Atlantic Ocean at the Amazon Fan near the Brazilian coast and also from the Ormen Lange gas field off the coast of Norway. We will suggest that these events caused significant changes in the flow of water at the surface of the ocean that, in turn, led to very rapid changes in the levels of rainfall. Scientists have already recognized that increased precipitation gave rise to changes to ecosystems (or, more precisely, to biotopes) that destroyed the mammoth steppe. However, much of the evidence we will use in this article to support our argument has been used to support other sorts of explanation for the extinction. Therefore, this primary evidence now appears to be in need of revision. Introduction About 11,000 years ago, all of the remaining herds of mammoths suddenly disappeared. During the Pleistocene, these mammoths once thrived on a vast, megafauna steppe stretching across the Northern Hemisphere. It may have resembled the African steppes of today with lions, hyenas and several species of large grazers being present. However, the debate about the cause(s) of the extinction continues. In North America, things appear to be simple – the appearance of early humans on that continent seems to coincide with the downfall of the megafauna. However, there are also … Read More

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Three-dimensional photographs of fossils (Part 1): Gastropods from the Paratethys Ocean

Dr Robert Strum (Austria) About 23Ma, the Paratethys Ocean covered a large area, including what is now the Vienna basin and Alpine Foreland. This mostly shallow ocean was a habitat for a large number of plant and animal species, which included numerous marine gastropods, some of which are discussed in this article. This is the first of three articles on three dimensional photograph of fossils. In this article, to give the reader a better impression of their volume and shape, the fossil shells have been photographed by using the stereoscopic technique I describe in Three dimensional photography of fossils (Part 3): Ammonites from the Northern Limestone Alps of Austria. Today, beautiful shells with various shapes and patterns, of recent marine gastropods, can be collected in large numbers along Mediterranean and tropical coasts. While this seems normal to us, finding marine molluscs in Austrian sandpits, far away from any ocean, is a little more surprising. Of course, the simple answer is that these shells are fossils from the ocean referred to above, which once covered what is now Central Europe. The fossils commonly originate from the Tertiary period, which lasted from 65Ma to about 1.8mya. More precisely, the fossils are from the Eggenburgian of the Miocene (23Ma to 5.3Ma), named after Eggenburg, a lovely village north-west of Vienna. (The Eggenburgian is a Lower Miocene stage of the Central Paratethys regional chronostratigraphic classification.) Fig. 1. Map exhibiting the position of Eggenburg in Austria and the arrangement of single sampling localities and related sights:1. … Read More

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Urban geology: A failed example of gabions as false urban geology from the Netherlands

Stephen K Donovan (The Netherlands) The provinces of Noord and Zuid Holland, including much of the Dutch North Sea coast and adjacent inland areas, are devoid of rocky exposures. In a region of flat-lying Pleistocene siliciclastic successions (Burck et al, 1956), there are no quarries, cliffs or other man-made or natural exposures of lithified rocks. The topography is slight, with the highest natural structures being the coastal sand dunes, in part preserved as a national park (Jelgersma et al, 1970). To offset this lack of geological ‘furniture’, the Dutch have enterprisingly imported and installed sundry rocks that fill what may be an unattractive void in the environment. These rocks vary from the minimalist, such as roadside boulders (in part, possibly erratics) (Donovan, 2015), to reconstructions of structures such as a replica of a natural bridge in Mississippian limestone slabs (Donovan, 2014). But, in some instances, reconstructions are unsuccessful or, at least, inaccurate, such as the false (Pennsylvanian) Coal Measure strata without identifiable coal beds in the national railway museum (Het Spoorweg Museum) in Utrecht (Donovan, 2018a). In this article, I describe further mock geological structures that fail in the details. Gabions are tools of the engineering geologist. Yet, when packed with cobbles of imported, grey Mississippian limestone, they may make convincing false sedimentary ‘beds’, at least from a distance, and are a not uncommon feature of the environment of Noord and Zuid Holland (Donovan, 2018b). (Vertical, dyke-like structures are rarer and are less successful as false geology; Donovan, research in … Read More

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Mysteries of time: A quest for the age of the Earth

David Alexander Gardiner (UK) The question of the age of the Earth and its former inhabitants is one of great interest to us all. Most are aware that the Earth is understood today to be approximately 4.6 billion years in age, but what is the story of the momentous quest – to unravel the mystery of time? Many early speculations as to the age of the universe abounded in ancient and medieval times. We are all familiar with the literalist understanding of the Old Testament, from which Archbishop Ussher famously calculated a 4004 BC date for the beginnings of the Earth. Yet, this was one of the shortest chronologies in existence: the Babylonians spoke of many hundreds of thousands; the Egyptians of many tens of thousands; and the Hindus many billions of years in their cosmological speculations of the past. However, all these early traditions were not scientific in basis. Rather, they were religious or philosophical and not based upon experimentation and observation. It would not be until after the Renaissance that people started employing scientific methodologies to unravel the mystery. Various early scholars speculated upon the Earth’s geological history, including Leonardo da Vinci, the universal genius. Leonardo noted that fossils had once been actual living creatures and that the ocean must have once covered the land. As regards the age of the world, however, few people dared to challenge the conventional wisdom based upon the Genesis narrative – one wonders what da Vinci’s own view might have been. However, … Read More

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Mysterious blue orbs of K2 granite

William Wray (USA) K2 granite is found near the base of K2, the mountain it is named after, in the Himalayas from a rarely visited site. K2, also called “Mount Goodwin Austen” is the second highest mountain in the world, rising to 8,611m (28,253 feet). K2 got its name from the British surveyor TG Montgomerie. The “K” comes from the Karakoram mountain range and the “2” means that it is the second tallest peak recorded. Fig. 1. An oval cabochon made from K2 granite found on K2, a mountain between Pakistan and China, revealing several bright blue azurite stains. The blue azurite stains formed after the granite cooled and hardened. (Photo by the author. Specimen from the William Wray collection.) K2 granite has impressive splashes of blue circles or orbs on its surface. The blue circles are azurite inside of white K2 granite rock. The white granite is fine-grained and composed of the minerals: quartz, feldspar, muscovite and biotite. The azurite stained parts of the granite, making blue dots, which range from a couple of millimetres to about two centimetres. Azurite has a relative hardness of 3.5 to 4 on the Mohs hardness scale, but assumes the hardness of the white granite, because the azurite is only a stain. The azurite formed after all the other minerals in the granite had cooled and hardened. With a hand lens or microscope, azurite spheres reveal that the azurite appears along the edges of mineral grains, in tiny fractures in the granite, and … Read More

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Stop the press: The Jurassic Coast starts in the Permian

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

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Rocks in Roslin Glen: A record of a swampy past

Mark Wilkinson and Claire Jellema (UK) Midlothian is an area of central Scotland that lies to the west of Edinburgh and is an area with strong geological connections due to a history of mining for both coal and oil shale. As a part of the annual Midlothian Science Festival (http://midlothiansciencefestival.com/), the School of GeoSciences at the University of Edinburgh offered a walk to look at some local geology and a talk about climate change research on the Greenland icecap. In addition, a ‘Dino and Rocks Day’ was attended by 380 people, proof (as if it were needed) that dinosaurs continue to fascinate the general public. The Edinburgh Geological Society also contributed with a session about Midlothian Fossils and a local historian talked about the history of coal mining in the area. The geology walk visited local exposures, in this case Carboniferous sediments including what may be the best exposed fluvial sediments in the area. The walk was advertised as “Rocks in Roslin Glen: a Record of a Swampy Past” and all 25 spaces were quickly booked. The location was Roslin Glen, which may sound familiar if you’ve seen the film, The Da Vinci Code, based on the novel by Dan Brown. We have not misspelled the name of the glen incidentally. For some reason, Rosslyn Chapel lies on the edge of Roslin Glen and the country park of the same spelling. The glen itself is a steep-sided valley of around 20m in depth, which carries the River North Esk roughly … Read More

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Introduction to the Messel Pit

Jack Wilkin (UK) The Messel Pit represents a Konservat-Lagersttätte dating to  the Eocene Epoch 47 million years ago. The site is in Hessen State in Germany, close to the city of Darmstadt. It is a disused oil shale quarry that was scheduled to become a landfill in the mid-1990s. Thankfully, due to public and scientific outcry, the site was designated as a UNESCO World Heritage Site in 1995. Ever since, there have been thousands of amazing and revolutionary discoveries. This article seeks to introduce this remarkable site and a glimpse into a lost world. Fig. 1. Amphiperca multiformis (HLMD-Me 8958). During the Eocene, global temperatures were much higher than they are today. The area that is now Messel was a volcanic lake surrounded by subtropical rainforests. The upper portions of the lake supported a wide diversity of organisms. The bottom waters where anoxic. This prevented bioturbation and inhibited bacterial decay leading to exceptional preservation. The lake would have periodically released toxic gases, in much the same way as Lake Nyos in northwest Cameroon, did in 1987 to lethal effect. The pit is comprised of oil shales. The rocks have a high-water content and any fossils recovered must be kept moist or else they will dry out and the specimen will be lost forever. They must also be stabilised with resin, in a process called the “transfer technique”. The Messel Pit is unusual in that both plant microfossils and macrofossils are founds found in abundance. The types of plants found at … Read More

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Colourful bluffs in Long Island recall the most recent ice age

Deborah Painter (USA) Imagine a tremendous piece of land moving equipment that scraped up the soil and some of the surface bedrock from four states within the United States’ Eastern Seaboard, carrying and dragging it all the way, before dumping it on a ridge off the shoreline. That is what essentially occurred with the final advance of the Wisconsinian ice sheet, the only one which left glacial deposits visible in New York State today. Long Island is a ridge of Cretaceous bedrock with glacial deposition. The moraines there have not been ground into sandbars and spits along the western end of the north shore as much as elsewhere, because of the sheltered nature of the Long Island Sound. Therefore, shoreline bluffs expose rocks as well as glacial loess. Fig. 1. Fishermen’s Drive takes you to the loess deposits. To park at the beach requires a permit. (Photo by JB Steadman.) If you find that your journeys take you to New York City, one of the world’s largest metropolitan areas, try to make time to visit Caumsett State Park at Long Island Sound. My own visit began when planning a visit to New York State’s Long Island to see my friend, Joyce Raber. She suggested various things that we might do: go to a Broadway play, go shopping and so forth. However, my list of things to do was typically “eco-tourist”. I wanted to visit the famed American Museum of Natural History in Manhattan, then see nearby Central Park, where the … Read More

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Bryozoans in the English Chalk

Dr Paul D Taylor (UK) We are very fortunate in Britain to host one of the most remarkable deposits in the entire geological record, the Chalk. The Late Cretaceous Chalk (with a capital ‘C’) is an extremely pure limestone, famous for the White Cliffs of Dover and responsible for the landscape of rolling hills and dry valleys, forming the ‘downs’ and ‘wolds’ that stretch through England from Devon in the southwest, to Yorkshire in the northeast. The economic importance of the Chalk to the early human inhabitants of Britain was enormous because the flints contained within it could be fashioned into axe heads and hard cutting tools. Why is the Chalk so special geologically? It is a rare example of a pelagic sediment – an open ocean sediment – that was deposited over the continental shelf. This occurred at a time when global sea-level was high and the supply of terrigenous clastic sediment into the sea was minimal. The Chalk is an oceanic ooze composed mainly of the disaggregated plates – coccoliths – of coccolithophores, planktonic microalgae with exquisitely engineered skeletons of calcite. Unfathomable numbers of coccolithophores sank to the seabed over a period of some 35 million years to produce the thick accumulation of Chalk that today extends over northern Europe and into western Asia. The Chalk is a favourite hunting ground for fossil collectors, yielding beautifully preserved specimens, especially of echinoids. But closer inspection of the Chalk shows that the dominant macrofossils are often bryozoans. These colony-forming invertebrates … Read More

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Volcanism in the ancient world

Dr Robert Sturm (Austria) In the ancient Greek and Roman world, volcanism was recognised as a divine phenomenon standing in close connection with the fire god, Hephaestus or Vulcan. Although there did not exist any term corresponding to the modern word “volcano”, people were aware of the destructive power arising from volcanic eruptions. Some early natural philosophers were already able to identify individual volcanic processes, such as lava flow and the generation of huge and extremely hot dust clouds. In the ancient Greek language, lava masses streaming downhill were simply named “rhea” (ῥύαξ or flow), whereas the Latin words “Vulcanius amnis” (Vulcanic stream), “saxa liquefacta” (liquefied rocks) and “massa ardens” (blazing mass) were used for the same phenomenon. Volcanoes were of enormous importance for the ancient Mediterranean world, because their eruptions caused the destruction of adjacent settlements and even the annihilation of entire civilizations. According to our present historical and archaeological knowledge, three volcanoes had an immense influence on the development of Mediterranean cultures: (1) the volcano of Thira-Santorini, which left behind the huge caldera visible today; (2) Vesuvius near the city of Naples; and (3) Etna on the island of Sicily (Fig. 1). Fig. 1. A satellite map of the Mediterranean region, including the position of the three volcanoes covered in this article. Despite the Thira-Santorini volcano being situated in the Aegean Sea, Vesuvius near Naples and Etna on Sicily, they are all considered to be part of the western Mediterranean Sea. (Photo: ©NASA.) In this article, I intend … Read More

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Urban geology: The strange tale of a windowsill

Stephen K Donovan and John WM Jagt (The Netherlands) Leiden, in the Dutch province of Zuid-Holland, is a city with a fine selection of fossiliferous building stones, mainly Mississippian (Visean, Lower Carboniferous) limestones. which preserve an array of fossils, such as rugose and tabulate corals, brachiopods, bryozoans, molluscs, and crinoids. However, this fine diversity of body fossils is not supplemented by a similar composition of trace fossils. Despite having examined these rocks over many years, when leading student fieldtrips and in collusion with co-workers, SKD has found no evidence of burrows, nor any borings in bioclasts, which can be locally common at some localities where Mississippian strata are exposed (for example, Donovan and Tenny, 2015). It is therefore of note to recognise an uncommon rock type among the building stones of Leiden that is dominated by burrows and lacks body fossils. This article highlights this distinctive building stone that has engrossed SKD for some years. The street Rapenburg (Fig. 1) in Leiden is a favourite route for building stone tours of the city. Although the dominant building materials are bricks, there are ample rocks to make a visit worthwhile. When SKD has led groups of students from the University of Leiden on geological excursions down the Rapenburg, the start is commonly at the North End Pub (Fig. 1). Fig. 1. Map of the centre of Leiden (modified after Van Ruiten & Donovan, 2018, fig. 1); Leiden Centraal railway station is north of the north-west corner of this map and less … Read More

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La Gomera: A short geological guide

Ken Madrell (UK) The island of La Gomera has an area of 370km2, it is 25km in diameter, has a maximum altitude of 1,487m (Alto Garajonay) and is situated approximately 40km west of Tenerife. Unlike the other Canary Islands, La Gomera has experienced a long and continuing eruptive break and is in a ‘postshield erosional stage’. Carracedo and Troll (2016) describe this as the stage when active volcanism has ceased, and erosive and denudational landforms are predominant (p. 39). The submarine base of the island shows that it rests on a shallower ocean bed than the surrounding islands. The emerged land mass is semi-circular in shape, with a radial drainage pattern from its centre near Alto de Garajonay. The dating of the island has proved problematic, as some of the earlier measurements placing its age between 15 Ma and 19 Ma have since proved to be inaccurate. More reliable estimates now put its age at between 10 and 11 Ma. Fig. 1. Roque Argando viewed from Lomo de la Mulata. La Gomera’s general stratigraphy comprises of three main rock sequences: (1) A Miocene basaltic shield, including a basal plutonic complex (that is igneous rock formed by solidification at considerable depth beneath the earth’s surface); (2) A nested felsic (that is, igneous rocks that are relatively rich in elements that form feldspar and quartz) stratovolcano (which is built up of alternating layers of lava and ash); and (3) The youngest Pliocene volcanism. Fig. 2. Sketch map of La Gomera, showing the … Read More

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Whitby Jet and the Toarcian Oceanic Anoxic Event

Arthur Speed (UK) One hundred and eighty million years ago in the Toarcian Stage of the Lower Jurassic Period, the Earth was very different from the world we know today. The continents were all clumped together in a supercontinent called Pangaea, which was just beginning to split apart. Sea level was approximately 100m higher than at present, such that much of Britain (including Yorkshire) lay beneath shallow seas. At this time, the Earth’s oceans were depleted in dissolved oxygen. The chain of events that caused this are complex, but can be traced back to a major volcanic event (Fig. 1). The eruption of the Karoo-Ferrar Large Igneous Province (LIP) spewed lava over what is now southern Africa and released vast amounts of carbon dioxide into the atmosphere. Just as happens now, the carbon dioxide resulted in global warming, which, in turn, had several effects on the oceans: Fig. 1. Volcanism during the eruption of the Karoo-Ferrar LIP may have triggered the Toarcian Oceanic Anoxic Event (Ulrich, 1983). Seawater became deficient in dissolved oxygen, because oxygen solubility decreases with increased temperature.Plankton thrived as a result of the warmer temperatures and increased nutrient supply, using up even more dissolved oxygen.Oceanic circulation was decreased, reducing the supply of cold oxygenated water to the oceanic basins.Warmer water released the green-house gas methane from the ocean floor, further accelerating global warming.The result was the formation of a layer of water that was deficient in oxygen throughout the Earth’s oceans. Its existence was first postulated in … Read More

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Geological transformation of Sharjah, United Arab Emirates

Khursheed Dinshaw (India) In this article, I will briefly deal with the fascinating and relatively recent geological transformation of the Sharjah region of the United Arab Emirates (UAE). Sharjah needs no introduction in terms of it being a popular tourist destination, especially for families. However, very few know how it was formed and subsequently transformed. In this article, I hope to explain this fascinating aspect of Sharjah. From the beginning At the beginning of the Miocene Period, 23 Ma, Arabia finally split from Africa along the Red Sea and the Gulf of Aden became a separate plate. This new plate moved in a northerly direction and collided with, and was subducted under, the Eurasian continent (Fig. 1). The Strait of Hormuz also closed as the remains of the Tethys Ocean formed a rapidly subsiding basin in which thick layers of salt were deposited. Large scale folding and faulting took place in the UAE producing hills of folded rock, such as Jebel Fai’yah and Jebel Hafit. Fig. 1. Granite from continental drift. In the eastern part of the UAE, uplift of the Al-Hazar Mountains began. This continued into the Pliocene Period, from 5 to 2 Ma. In the late Miocene and Pliocene, the Sharjah region finally rose above sea level and the landscape we see today was formed. Fig. 2. Various rock exhibits at the Sharjah Natural History and Botanical Museum. When the region known as Sharjah rose above sea level, it allowed the area to be covered by the moving … Read More

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Three-dimensional photographs of fossils (Part 2): Stereophotography of ancient micro-organisms

Dr Robert Sturm (Austria) In the past 60 years, microfossils have increasingly attracted the attention of earth scientists for several reasons. Firstly, they are highly useful in biostratigraphic respects; secondly, they can be easily determined by light- or electron-microscopic studies in most cases; and thirdly, sampling, preparation and storage of microfossils is carried out according to well-defined and mostly simple procedures. By definition, microfossils are the petrified relics of micro-organisms, which have mainly colonised aquatic habitats of the Tertiary or older epochs of earth history. Most of these ancient micro-organisms measured less than 1mm in size, so any scientific documentation of their remains requires a magnifying glass or, better still, a microscope. In certain cases, the size of microfossils is between 10µm and 100µm, which necessitates the use of an electron-microscope to elucidate their structure and to determine the species. Fossils measuring less than 10µm in size chiefly belong to another category of fossils, that is, nannofossils (for example, coccoliths). Typical representatives of microfossils include radiolaria, foraminifera, ostracods and diatoms, which may be used as index fossils within certain local or regional strata. A special role is taken by conodonts, which are small dental structures belonging to the so-called ‘conodont animal’. This is supposed to be distantly related to the lancet fish (Brachiostoma). While foraminifera, radiolaria and ostracods have colonised the earth with varying abundances since the Early Cambrian (570Ma), the occurrence of conodont animals seems to be restricted to the time period ranging from the Middle Cambrian (about 550Ma) … Read More

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Boxstones: In search of Miocene Suffolk

Tim Holt-Wilson (UK) The date is 24 May 2014 and I am browsing across East Lane Beach at Bawdsey in southeast Suffolk. A brown lump of sandstone with a white fossil shell impression catches my eye. A boxstone. This is the first one I have ever found with a fossil in it. Looking closely, I see that the sea has abraded the shell’s outlines, although the margins have survived better than the rest, so it should be possible to identify the specimen (Fig. 1). Fig. 1. Boxstone, found 24 May 2014. Boxstones are fragments of a vanished world. They are all that remains of a lost geological stratum in Suffolk called the ‘Trimley Sands’ (Balson, 1990), although deposits of similar age are still present across the sea in Belgium and other parts of Europe. Boxstones are lumps or concretions of brown sandstone, which may contain shell fossils and – if you are extremely lucky – bones and teeth. They are beach-rolled and rounded, and typically measure between 5 and 15cm in diameter. The sand is mostly quartzose, with a rich assemblage of secondary minerals, and is cemented with carbonate-fluorapatite (a phosphate mineral) and calcite (Mathers and Smith, 2002). Boxstones can be found scattered sparsely across the shingle beaches at Bawdsey and Felixstowe Ferry (Fig. 2), and in situ as a common component of the basement beds (nodule beds) at the base of the Coralline Crag and Red Crag formations of southeast Suffolk (Fig. 3). They are eroding out of the … Read More

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Saltwick Bay, North Yorkshire

Emily Swaby (UK) Saltwick Bay is located along the Yorkshire Coast, between Whitby and Robin Hood’s Bay, and can be accessed from the Cleveland Way, which passes the spectacular Whitby Abbey. The geology of the area is predominantly Jurassic in age, with the site often being described as a ‘fossil treasure trove’. The bay yields a wide variety of specimens, including common ammonites and belemnites to rarer finds such as marine reptiles, Whitby Jet and even dinosaur footprints. Even though Saltwick Bay is close to Whitby, it is still a very productive locality and you never leave empty handed. In fact, it is a good location for families and beginners. The walk to Saltwick Bay from Whitby itself is approximately 2.4km and provides many picturesque views of the abbey, the harbour entrance and the remarkable coastline. The steps leading down to the beach are located just past Whitby Holiday Park, but can sometimes be slippery during winter months. It is also recommended that you check tide times for the area before arriving, as high tide can limit the extent of accessibility and could potentially cut you off. Fig. 1. The steps descending down the cliff to the bay. Once you have made your way down the steps, fossils can be found immediately among the scree or in the shingle. However, it is advisable stay away from the base of the cliffs, as rock falls are common, with loose fragments of shale constantly falling down. Fig. 2. The Nab is a … Read More

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Colorado mountain memories

Steven Wade Veatch (USA) While headed for the California Gold Rush of 1849, George Giggey (who was my great-great-grandfather) first made his way through the mountainous and untamed wilderness of what would later become Colorado. He was among a group of young men, who were determined to make a new life, fortune and future in the American West. After working in the Californian goldfields, he turned his attention to Colorado, where he prospected for gold for a while and then returned to the East. In 1865, George Giggey returned to Colorado with his family of ten children and built a homestead in the wilderness near what would become, in just a few years, the town of Caribou. The town developed around the Caribou silver mine that was discovered by Sam Conger in 1868. George Lytle, one of Conger’s partners, was from British Columbia and named the mine after his caribou hunting trips in Canada. By 1870, the Caribou Mine was in full production and was shipping ore down Coon Trail, to the nearby settlement of Nederland for processing. By 1872, the frontier town of Caribou built a much needed schoolhouse. Three of George Giggey’s boys attended Caribou’s first school session. They were: George Leon (my great-grandfather), who was 14 years old; Adelbert, age 7; and Charley, who was only 6 years old. I can feel the boy’s excitement when they took their seats in the one-room schoolhouse, with new furniture, blackboards, maps, globes and a new teacher – Miss Hannah … Read More

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Finders, keepers: The lost world of some Isle of Wight geological heroes

Martin Simpson (UK) There is a growing misconception that most of the earliest important fossil discoveries were made by a select few famous geologists – established names, who were supposed to have ‘found’ everything in their collections. In reality, however, the true ‘discoverers’ of the original specimens were an often unknown or forgotten assortment of amateurs, labourers, beach-combers, longshoremen or quarrymen: opportunists, who were finding ‘new’ material with surprising regularity. These people not only had local knowledge, but also had the distinct advantage of being in the right place at the right time, thanks to the hours they devoted to searching. On the other hand, the early geological pioneers were fervently adding to their private museum cabinets by whatever means possible. As news of major finds of unusual fossils came to their attention, perhaps by way of the reports in some of the provincial broadsheets mentioned later, the more diligent and successful collectors (the acquirers) put their money where their mouths were and purchased directly from the sources (the finders). Eventually some of this material found its way to the academics and their institutional museums (the keepers). In the case of the Isle of Wight – that classic locality for Cretaceous and Palaeogene fossils – the earliest and most important historical discoveries have been attributed to a small group of generalised geologists. These include William Buckland, Adam Sedgwick, William Fitton, Edward Forbes and the surgeon, Gideon Mantell between the 1820s and the 1850s; and later to a whole host of … Read More

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Carbonate platforms and coral reefs: The Coralline Oolite of the Yorkshire Upper Jurassic – a prime source of palaeontological information

Keith Eastwood (UK) The Malton Oolite Member of the Coralline Oolite Formation (Corallian Group), as exposed in the Betton Farm South Quarry (TA00158555) at East Ayton, near Scarborough (Fig. 1), provides a wealth of fascinating palaeontological and sedimentological information. Examination of outcrops within this small quarry enables the geologist to reconstruct the palaeoenvironment of deposition of the Betton Farm Coral Bed, a localised system of patch, ribbon and framework reefs that developed during the Upper Jurassic. Fig. 1. Locality map of the Betton Farm and Spikers Hill quarries. Geological outcrops from BGS Sheet 54 (Scarborough) (1998), (Wright, 2001, p.157, fig.4.20). Total image © Joint National Conservation Committee; geological outcrop map – British Geological Survey © NERC. Redrawn and reproduced with permission. The lithology and textural characteristics of the Malton Oolite Member provide a sedimentological basis for the interpretation, but the fossil content adds definitive ecological and climatic insights. The Malton Oolite is the upper of two oolite members in the Coralline Oolite Formation (Fig. 2). The lower one, the Hambleton Oolite Member, is not seen in the Betton Farm Quarries (which consist of two quarries: Betton Farm North Quarry and Betton Farm South Quarry, north and south of the A170, respectively) but is fully exposed in the Spikers Hill Quarry (SE 980863) just 3km to the WNW (Fig. 1). This location is important in providing a regional depositional context for the Betton Farm deposits, even though the upper surface of the intervening Middle Calcareous Grit Member is a minor unconformity. … Read More

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Volancoes of Big Island, Hawaii (Part 3)

Dr Trevor Watts (UK) This is the last of a three part article about the volcanoes of Big Island, Hawaii. In the first part, I discussed their background and explained some of the terms used to describe the lava that can been seen there. In the second, I discussed some of the highlights that my wife and I saw during our several trips to the island, including in October 2014. And in this part, I will continue to describe what we saw. Fig. 1. One of the kipukas (that is, untouchedby- lava areas of forest). The abandoned lava cliff at Kalapana This is a stretch of old cliff face that is now several hundred metres from the sea. It is located among the flows of February 1992 to October 2003, but the area was re-flooded with lava between 2007 and November 2013, when the ocean entry hereabouts was blocked. The site is just under 5km southwest of present-day Kalapana near Poupou, where the Royal Gardens lava flow reached the coast. The walk is well worth the effort for the variety of lava formations, the many tumuli or blisters of lava, and the coastal scenery along the present cliffs. We were guided here by Gary Sleik, who lives on the lava at Kalapana. Fig. 2. The first section of cliff face, with the lens-shaped tube blocked by cindery flow. The cliffs are backed up by a small kipuka, which is an area that was left untouched, as the lava flowed around … Read More

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Volancoes of Big Island, Hawaii (Part 2)

Dr Trevor Watts (UK) This is the second of a three part article about the volcanoes of Big Island, Hawaii. In the first, I discussed their background and explained some of the terms used to describe the lava that can been seen there. In this part, I will discuss some of the highlights that my wife and I saw during our several trips to the island, including in October 2014. A night walk to the flowing lava from Kalapana This was one of the major highlights of our previous trip in 2013. Several local guides conduct walks across the old lava (mostly 1981 to 2013 flows) to wherever the current flow is best viewed. Our lead guide was Dave Ewing (postewing@gmail.com or (808) 315-2256) and our group met up at his house, located on private properties beyond the “End of the road” signs at Kalapana. This house is one of the very few to survive the 2010 flow, which came through the Royal Gardens subdivision and into Kalapana. Fig. 1. A going away party to mark the long-expected event of the house burning at Kalapana on the night of 25 July 2010. My thanks to Darlene Cripps and Gary Sleik for this picture. We began in late afternoon, with around a dozen people in the group. The walk initially passed the remnants of some of the other homes – a corrugated roof, a fridge, some pilings, and so on, before getting onto the fresh lava. It was almost five kilometres … Read More

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