It is a wonderful state of affairs that we can not only now write detailed books about planetary geology and geomorphology of the bodies in the solar system, but we can also illustrate them with wonderful photographs.
I quite like regional guides books, even about areas I haven’t been to and am unlikely to visit. That isn’t the case for South Wales, which is one of my favourite areas in the UK for both scenery and geology. Therefore, this guide is another good addition to my collection and will no doubt accompany me soon on another holiday in the Principality.
Almeria is a province in southeast Spain, situated in the furthest southeast part of the Iberian Peninsula. It is a classic area for southern European and Mediterranean Neogene and Quaternary geology.
Ruth Crosbie (UK) The Loch Lomond and the Trossachs National Park has a unique and very visible geological character. This, and the geomorphological processes that have taken place in the area have been fundamental in shaping the outstanding landscape and scenery of the park. Fig. 1. The outstaniing landscape and scenery, seen today at Lock Lomond and the Trossachs National Park, has been shaped over millions of years by geomorphological processes. Rolling, relatively low-lying farmland along the southern margins of the park is underlain by Silurian to Carboniferous sedimentary rocks. North of the Highland Boundary Fault, this rolling country gives way to increasingly mountainous land, underlain by more ancient metamorphosed rocks. Many of the visible landforms represent the actions of glacial processes. Classic ‘U’-shaped valleys, such as the north Loch Lomond basin and Strathfillan, were carved by glacial ice. Other features, such as drumlins near Tyndrum and the rolling landscapes south of the Highland Boundary Fault, are the result of sediments deposited by melting glaciers. Such contrasts in the geology and landforms are reflected in similar marked contrasts in land-use patterns. Geological Structure The park contains a wealth of geological and geomorphological features, including some of national and international importance. The Highland Boundary Fault, which separates the Highlands from the Scottish Midland Valley, is well known. Within the park, the fault runs from Arden through Balmaha, Aberfoyle and Loch Venachar, and its line is clearly visible through the islands of southern Loch Lomond. Although less well known, other features include … Read More
Stephen K Donovan (The Netherlands), David AT Harper (UK) and Roger W Portell (USA) In his latest book, Ted Nield (2014) reflects on building stones and what they tell the geologist about where they are. Once upon a time, building stones in Britain were derived locally and told the informed observer something of the local geology (apart from, of course, the exotic stones imported for banks and office blocks). That is, they were built of local stone from the local quarry. Today, stone is imported from as far afield as China, where once they would have been derived locally by horse and cart or canal boat. One place where local stone is still used is Antigua in the Lesser Antilles. For example, Jackson and Donovan (2013) described an attractive, green chloritized tuff, which is used throughout the island as a bright and distinctive building stone. Many old structures in rural areas are still constructed of stone, such as walls, buildings (including ruins) and, the subject of this article, disused windmills. For a general introduction to the geology of Antigua, see Weiss (1994) or Donovan et al (2014). All major stratigraphic units are Upper Oligocene; the regional dip is to the northeast. Betty’s Hope The Betty’s Hope site, in the parish of Saint Peter in eastern Antigua (Fig. 1), is an open air monument administered by the Museum of Antigua and Barbuda. Fig. 1. Outline map of Antigua (redrawn and modified after Weiss, 1994, fig. 3), showing the principal geological subdivisions … Read More
Dr Sue Beardmore (UK) When most people think of Scotland, the images that come to mind are those of high, heather covered mountains like Ben Nevis, islands like Skye, Arran or Rum, or the endless rugged coastline of the northwest coast. However, there is another half to the country, along the east coast, which few people have explored. For example, the county of Moray offers Burghead Bay, where pill boxes sit half submerged in sand, or there are the frequently climbed sea cliffs below Cummingston and Covesea, and Findhorn Bay, the only natural harbour on the south side of the Moray Firth, where shipwrecks litter the beaches at low tide alongside remnants of an old settlement destroyed by shifting channels. Fig. 1. Baryte mineralisation in Permian sandstone at Hopeman.In terms of geology, the Moray shore provides evidence of the ancient landscape 250mya, easily found by following the coastal path, a walkable distance east from the village of Hopeman. A short detour onto the beach, behind the brightly coloured huts, reaches small outcrops of Permian sandstone, the Hopeman Sandstone Formation, which occurs continuously along the coast for several kilometres. At this particular spot, the sandstone is heavily mineralised with barytes, primarily as cement holding the medium-sized grains in place, but also as concentrations a few centimetres across that give the outcrop an overall speckled appearance and nearly obliterate the original bedding (Fig. 1). Such an outcrop can also be found near Covesea Lighthouse, as can fluorite in characteristic (but difficult to … Read More
Russell Garwood and Alan Spencer (UK) The Carboniferous Period is a fascinating time in earth history. It spanned 60Ma (359.2 to 299.0Ma), towards the end of the Palaeozoic era, falling between the Devonian and Permian. During the Carboniferous, the supercontinent Pangaea was assembling and the oceans were home to invertebrates such as corals, bryozoa, ammonoids, echinoderms, trilobites and crustaceans. Fish were also well represented (especially sharks), which were rapidly diversifying at the time. The continents were no barren wasteland either – they were host to some of the first widespread terrestrial forest and swamp ecosystems. In these lived both invertebrates, which had crawled onto land by the Silurian period (at least 423mya) and vertebrates, which were relative newcomers to this realm. This article provides us with an excuse to write about the Carboniferous. We will first introduce the geology and palaeogeography of the Carboniferous, including an overview of the most common mode of preservation we see in terrestrial fossils. Then, we will provide an overview of terrestrial life during the period, as land-based ecosystems of this age are among the best known from the Palaeozoic and an exciting time in the history of life. Fig. 1. Global paleogeographic reconstruction of the Earth in the late Carboniferous period 300mya. (C)opyright Dr Ron Blakey (Wikipedia Creative Commons). Carboniferous geology The Carboniferous is split into two epochs, the Mississippian (or Lower Carboniferous; 359.2 to 318.1mya) and the Pennsylvanian (or Upper Carboniferous; 318.1 to 299.0mya). As we shall see, the two are associated with … Read More
Stephen K Donovan (The Netherlands) The last weekend in September 2013 was sunny after more than two weeks of grey skies, rain and even some fog. Saturday was spent as planned, moving bookcases ahead of Karen’s insatiable paintbrush, the walls changing from lime green to white as she progressed. Sunday morning was spent putting some books back onto bookcases, but I had to get out in the afternoon. It might be six months or more before I could venture out again in only a T-shirt, shorts, training shoes and floppy hat. I had my son, Pelham, as field assistant, but where to go? The answer was obvious to me – this was the day to consummate a project that I’d had in contemplation for some years. The Netherlands is not renowned for its pre-Pleistocene geology. There is the type Maastrichtian (uppermost Cretaceous) in the south, some fine Triassic near the German border in the east and odd spots of poorly exposed Tertiaries. Where I live, in Hoofddorp (near Amsterdam Schiphol Airport), we live below sea level on the bed of a drained lake; but what Hoofddorp lacks in surface exposure, it makes up for in building and ornamental stones. To the south and east of the town is a business park in the Beukenhorst district, with a fine range of architectural styles and building materials, both man-made and natural stone. One road, Siriusdreef, in this part of town has intrigued me for years. Street art is widespread in the Netherlands … Read More
Dean Lomax (UK) A Lagerstätte is a sedimentary deposit that exhibits exquisite fossil richness, detail and/or completeness, often preserving fine details, including soft parts, which wouldn’t normally be found as fossils. There are two main types of fossil Lagerstätten: concentration Lagerstätten, which simply consists of large concentrations of fossils found together in deposits such as bone beds; and conservation Lagerstätten, where the defining feature is the preservation of quality rather than the quantity of fossils. A few examples of famous Lagerstätten include the Eocene Green River Formation, which is primarily known from Wyoming, but can also be found in Colorado and Utah. Famous European Lagerstätten include the Solnhofen Formation of Bavaria, Germany. This has produced some spectacularly preserved fossils, including Archaeopteryx, which is considered to be a transitional fossil between dinosaur and bird evolution. Another famous Lagerstätte, situated in central Germany, is the Messel Pit (Grube Messel). This quarry contains Eocene-aged strata and has produced specimens such as Darwinius masillae, identified as a basal primate and described in 2009. Fig. 1. A group searches for fossils in one of the privately owned quarries. (Photo by Dean Lomax.) Geological setting and location Menat is a small village located within the department of Puy-de-Dôme, Auvergne in central France, near the town of Gannat, a town famous for Oligocene and Miocene-aged fossil deposits. The geology of Menat consists of sedimentary rock that includes soft shale layers (including bituminous, pyritious and oil shales) and hard layers consisting of diatomite. The preservation of the fossils … Read More
Robert Broughton (UK) The end Permian mass extinction occurred 251mya and marked the end of the Palaeozoic era. The loss of life is currently estimated to consist of 95% of the marine fauna and around 70 to 77% of the known terrestrial fauna (where the fossil record is inevitably less complete). This article will provide an overview of the many events and processes that played a part and a discussion whether they can all be attributed to a single, root cause. Reef evidence At this time, the landmass was united into the single, super-continent of Pangea, surrounded by warm shallow seas with abundant reef systems. This extensive reef fauna supported a variety of suspension feeders (for example, crinoids, rugose and tabulate corals, and so on), which were the most heavily hit by the extinction event, with all the known corals dying out. Modern scleractinian corals only appeared in the Triassic and there is a considerable gap in the coral fossil record at this time. Other reef inhabitants, such as the last phillipsid trilobites also became extinct. All these creatures were sessile or relatively immobile inhabitants of the reefs that occupied a relatively narrow zone on the continental shelf. This habitat must have been destroyed almost globally by a number of factors, but importantly, the single shelf margin around Pangea meant there was no other shallow reef environment for the fauna to migrate to. Fig. 1. Reef evidence. Tectonic activity The single continent of Pangea was always doomed to split apart. … Read More
Dr Robert Sturm (Austria) Ancient civilizations had a high demand for raw materials, like clay, diverse rocks and, most of all, metals. These were required for buildings, crafts, agriculture, their armed forces, financial concerns, art and culture. Clays and rocks produced by opencast mining primarily served for the production of bricks and building blocks, which were used for civil and hydraulic engineering. They were additionally extracted for the manufacture of durable goods and art objects, such as dishes and statues. Metals – like gold, silver, copper, tin, iron and lead – being essential raw materials in antique civilisations, were commonly produced by underground mining. Gold and silver were mostly used as raw material for ancient coins. The use of noble metals in monetary economy has been going on since the seventh century BC, when barter trade was successively replaced by a monetary economy. Copper, tin and iron was mostly produced for the manufacture of arms, whereas lead was, among other things, used for the production of water conduits and as a stain for ornamental painting. Fig. 1. Some examples for the use of metals: lead was, among other things, used as stain for ornamental painting (left), whereas silver was used for coins (right). Ancient techniques used for the mining of raw materials Sufficient supplies of metallic and mineral raw materials required systematic mining, since only gold was found in large enough amounts in washes of brooks and rivers to make panning worthwhile. Other metals usually occurred as chemical components of … Read More
Stephen K Donovan (The Netherlands) My writings on urban geology are normally centred in the area around my home in Noord Holland, but sometimes I am lucky enough to travel. A personal wish that I have had since I was a teenager was to see and, if possible, board a dreadnought battleship. This whim was finally satisfied in March 2014, when I visited the last surviving dreadnought from World War I, the USN Texas, preserved at the San Jacinto Battleground State Historic Site, near Houston (Fig. 1A). What I had not realised was the battleship is interred adjacent to the site of the Battle of San Jacinto, where a rag-tag army of insurgents, following defeat at the Alamo and Goliad, decisively defeated the Mexican army in under 20 minutes in April 1836, thereby winning independence from Mexico for Texas. Fig. 1. Two breathtaking exhibits at the San Jacinto Battleground State Historic Site, near Houston, Texas. (A) The dreadnought battleship, USN Texas, commissioned in 1914 and a veteran of two world wars. (B) The San Jacinto Monument, built in 1936 from Cordova Cream Shellstone and the tallest memorial stone column. The San Jacinto Museum of History is in the base. The Battle of San Jacinto is commemorated by a towering monument (Fig. 1B), which is the tallest memorial stone column, about 175m, and some 4.5m taller than the much better known Washington Monument in Washington DC. The San Jacinto Monument is visible over a wide area of this flat coastal plane … Read More
Benjamin Kear (Australia) and Georgios Georgalis (Greece) Most people are familiar with the famous giant tortoises of the Galapagos Islands – isolated oddities evolving in the absence of predators on a remote tropical paradise. However, as little as 5mya, continental landmasses (including Europe, Africa and India) also had their own species of giants. However, these were nearly three times the size of their modern cousins, probably close to the mass of a small car, and would have rivalled some dinosaurs for being among the most colossal reptiles of all time. Fig. 1. A life-size reconstruction of the European gigantic tortoise Cheirogaster as displayed in the University of Athens Palaeontological and Geological Museum. This model represents a massive individual of a carapace length of around 2m and was based on finds from Pikermi, near Athens, and the island of Lesvos. The best preserved gigantic tortoise fossils (as opposed to the merely ‘giant’ ones) have been found in Mediterranean Europe, particularly France, Greece and Spain, and were described in the scientific literature as early as 1877. Yet, despite an impressive chronicle of discoveries, the inter-relationships between these different kinds of gigantic tortoises are far from adequately understood. The present, albeit tentative, consensus is that there are at least three separate lineages, all of which achieved maximal body size at about the same point in geological time. Cheirogaster, the genus found in Europe, has a long fossil history stretching back some 50mys to the Eocene and includes up to 11 species. It is … Read More
Henk Oosterink (Netherlands) The Lower Muschelkalk (from the Anisian age of the Middle Triassic) of the quarry at Winterswijk in The Netherlands is well known for its beautiful and sometimes abundant finds of reptile footprints and bones. A few, almost complete, skeletons have even been found. Most of the bones come from marine reptiles within the Sauropterygia (that is, ‘winged lizards’, referring to their paddle-like flippers) group. The quarry is one of the most important sites for Triassic reptiles in the world. Every year, between 2,000 and 3,000 people visit this quarry on excursions and during open days, most being fossil collectors. Many new forms of life The Triassic Period is characterised by an explosive development of many reptile groups. For instance, at the end of this period, the dinosaurs appeared. Many new forms of life developed in terrestrial and marine environments. In the Tethys Ocean and its epicontinental seas, some reptiles adopted a semi-aquatic lifestyle allowing them to be functional in the sea as well as on land. Many of these reptiles belonged to the Sauropterygia. Sauropterygians are diapsids – reptiles are divided into two groups, anapsids that include turtles and diapsids that have two holes in the skull behind the orbit. Their skulls have upper temporal openings and, on the back of the skull, the quadrate is immovable and is connected to the squamosal. The sauropterygians lived mainly in the sea, but they did come ashore, for instance, to lay their eggs. This reptile group appears for the … Read More
Paul D Taylor and Consuelo Sendino (UK) Last week, In the first par of this two part series (see Dinocochlea (Part 1): The mysterious spiral of Hastings) we introduced Dinocochlea ingens, a gigantic spiral fossil from the Lower Cretaceous Wadhurst Clay Formation of Hastings, Sussex. Discovered in 1921 during the extension of St Helens Road near Old Roar Glen, this fossil immediately excited local and, indeed, national interest. The specimens were despatched to the British Museum (Natural History) where BB Woodward, a mollusc specialist who had recently retired as chief librarian, formally described the fossil as the new genus and new species – Dinocochlea ingens. The clue to Woodward’s interpretation of the fossil is in the name Dinocochlea, meaning ‘terrible snail’. Woodward (1922) considered Dinocochlea to be the largest snail that had ever lived. By piecing together the fragments found by the workmen building the road, he was able to reconstruct the supposed snail as a monster over 7 feet tall, 14 inches wide and with 23 spiral whorls (Fig. 1). Fig. 1. Plaster reconstruction of Dinocochlea, measuring more than 2m in length. Not a snail For a short time, Dinocochlea achieved celebrity status and was exhibited in the public galleries of the BM(NH) between the wars. However, its identity as a colossal snail was soon to be challenged. One of Woodward’s colleagues, the eminent fossil mollusc researcher LR Cox, was the main critic. Cox (1929, 1935) pointed to the variability in the tightness of spiral coiling between specimens of … Read More
Paul D Taylor and Consuelo Sendino (UK) Spiral structures in nature hold a particular fascination on account of their beautiful yet twisted symmetry. The logarithmic spiral coiling of ammonite shells and rams’ horns, the corkscrew helix of a plant tendril, and the planar spiral of a hurricane when viewed from space, all have an aesthetic appeal beyond that of simpler geometrical shapes. Fig. 1. The site in Hastings, as it appears, today where Dinocochlea was discovered during road construction in 1921. This is the first of a two part series on Dinocochlea. The second can be found at: Dinocochlea (Part 2): A possible solution to the mysterious spiral of Hastings. When huge spiral objects were unearthed during road construction in Hastings, almost one hundred years ago, it was not surprising that they attracted the immediate attention of geologists. To this day, the origin of these spirals from the Lower Cretaceous Wadhurst Clay is a puzzle. The story is as follows. History of the find In 1921, St Helens Road in Hastings (now the A2101) was extended westerly to meet up with Seddlescombe Road North (now the A21), thereby providing a bypass to Hastings town centre. Close to Old Roar Glen (a well-known local beauty spot) the workmen excavated a shallow cutting and came across some huge spiral structures lying horizontally in the rock. The engineer in charge of the roadworks immediately notified the Hastings Museum. Those specimens not already bagged as rockery stones by local inhabitants were sent to Dr … Read More
Mark Wilkinson (UK) From much of the coast along the Firth of Forth in southeast Scotland, and from coastal hills such as Arthur’s Seat in Edinburgh, the impressive piece of rock called the Bass Rock forms a prominent landmark. This steep island is the neck of a Lower Carboniferous volcano, rising 107m above sea level. Scuba divers, on the north side of the island, have shown the sea bed to be around 40m in depth, so the neck would be 150m high if we could see it all. The rock is made of phonolitic trachyte, that is, an alkali igneous rock with less silica content than a ‘normal’ trachyte, so the alkali feldspar is accompanied by one of the silica-deficient feldspathoid minerals, such as analcime. Unfortunately, this interesting mineral assemblage is too fine-grained to see easily, except in thin sections under a microscope. In winter, Bass Rock is a dark brown as might be expected, but, in summer, it turns white from both the seabirds that crowd every available surface and their accumulated guano. The shape of the island is significant – clearly the igneous rock was more resistant to erosion than the surrounding sediments into which it was intruded. These country rocks are not visible now, having been eroded away to below water level, with an estimated one kilometre or more of overlying rock removed since the time of intrusion, along with any surface eruption products, such as lavas and pyroclastic rocks. Fig. 1. The Bass Rock from the west. … Read More
Dr Michał Zatoń (Poland) The Middle Jurassic Bathonian stage, which is preceded by Aalenian and Bajocian and overlaid by the Callovian, was established on the basis of oolitic limestones outcropping at Bath in Somerset. This historical and English connection is a major reason I have chosen the Bathonian as a topic for Deposits Magazine. The Bathonian clays in Poland, like the English classic Kimmeridge Clay or Callovian Oxford Clay, are characterised by their rich fossil content. Although some years ago, the Bathonian clays from Poland were not as well known as these two English formations, today they have become progressively more recognised outside of Poland. This is due to an increasing number of publications dealing with different aspects of the clays and the 7th Jurassic Congress held in Kraków (southern Poland) in 2006, during which scientists from all over the world had the chance to meet and actually look at the Bathonian clays. Geological and palaeogeographical background The best outcrops of Bathonian clays are in southern and south-central Poland, in an area called the Kraków-Częstochowa Upland (Fig. 1). Here, the Jurassic rocks, and especially Oxfordian (Upper Jurassic) limestones, form a distinct belt stretching approximately in a south-east to north-west direction. That is why the late Professor Stefan Zbigniew Różycki in 1960, when comparing the area with such classic areas as the Swabian and Franconian Jurassic, called it the ‘Polish Jura’. Fig. 1. A map of Poland without the Cenozoic cover: 1. Pre-Jurassic, 2. Jurassic, 3. Cretaceous; PJ – Polish Jura. … Read More
Sebastian Lüning (UK) Morocco is a popular tourist destination. Most people travel to the white beaches of Agadir to sunbathe and relax, to watch the magicians on Djemaa el-Fna square in Marrakech, or to go shopping in the UNESCO-protected Osouk of Fes. However, Morocco has much more to offer. Some of the most attractive specimens found at international fossil fairs originate from this country. Morocco is home to exceptionally well-preserved trilobites and attractive Orthoceras assemblages from the Palaeozoic. The beds containing these fossils are systematically mined in the Anti-Atlas. Other fossils, such as goniatites and ammonites, complement the diverse palaeontological national treasure. Fig. 1. Location map of geological sites mentioned in this article. 1) granites near Tafraoute, 2) algal mats near Ouarzazate, 3) Ordovician glaciation, 4) Silurian graptolithic shales, 5) Orthoceras limestones, 6) Devonian mud mounds and Merzouga sand dunes, 7) Triassic Argana river sands, 8) Cascades d’Ouzoud, 9) Friouato karst shaft, 10) Dades Gorge, 11) blowholes near Agadir and Cretaceous oysters, 13) Amesfrane cliff. These fossils are part of an exciting geological past. This article aims to guide you through the highlights of Morocco’s geological history, exploring the stories behind the country’s natural wonders and its multi-million-year-old inhabitants. Concealed in its spectacular mountain chains are some fascinating snapshots from the past. Our trip will commence at the very beginning of this history and will take us gradually forward through time. We will visit various sites on a route starting in the Precambrian of the Anti-Atlas, in the southern part … Read More
Dr Steve Koppes (USA) Hikers visiting the Kilauea Iki crater in Hawaii today walk along a mostly flat surface of sparsely vegetated basalt. It looks like parking lot asphalt, but, in November and December 1959, it emitted the orange glow of newly erupted lava. Now, a precision analysis of lava samples taken from the crater is giving scientists a new tool for reconstructing planetary origins. The results of the analysis, by the University of Chicago’s Nicolas Dauphas and his associates, were published in the 20 June 2008 issue of the journal Science. Fig. 1. Eruption Hill in Kilauea Iki crater on the Big Island of Hawaii. In December 1959, lava spurted 580m feet high from this location. Working with lava samples from the crater, scientists at the University of Chicago and elsewhere have devised a new tool for reconstructing planetary origins. (Photo: Steve Koppes.) The researchers selected Kilauea Iki for their study because scientists have drilled it for samples many times over the years as it cooled. This sequence of samples makes the lava lake a perfect site for studying differentiation – the separation of minerals and elements as magma cools and hardens. In particular, a close examination of iron isotopes – the slight variations the element displays at the subatomic level – can tell planetary scientists more about the formation of crust than they previously thought, according to Dauphas and co-authors, Fang-Zhen Teng of the University of Arkansas and Rosalind T Helz of the US Geological Survey. Dauphas informed … Read More
‘Introducing Natural Resources’ is the latest in the Dunedin Academic Press series of introductions to scientific subjects, in particular, the earth sciences. You will probably be aware that I have positively reviewed a large number of them for this magazine, and this new guide is no different.
The Geologists’ Association have extended their excellent series of geological guides by producing what some people (including me) would think at first was a slightly self-indulgent couple of volumes on ‘Devonshire Marbles’.
Rosalind Jones (France) “Time and tide wait for no man” and “truth is often stranger than fiction.” Both these sayings apply to Scotland, especially Argyll with its islands at ‘the edge of the world’. Here, historic stones – some truly associated with destiny, others more dubiously linked by legend – fascinate and abound. Fig. 1. Perched erratic, Ben Hogh, CollColl and Tiree, to the northwest of Mull and Iona, are non-identical ‘twins’. Coll is rugged and rocky; Tiree is low, fertile and flat. However, in common with islands of the Outer Hebrides, both have pure white strands of calcareous sand made chiefly from maerl, backed by sand dunes of flower strewn machair (a low-lying grassy plain found on some of the northwest coastlines of Ireland and Scotland, in particular, the Outer Hebrides). Individually, they have their own strange, legendary stones – glacial erratics that have drawn myth to themselves and one which ‘rings’ its own warning today. Fig. 2. Sand dunes and white maerl sandy beach, Isle of Coll.Maerl is formed when Atlantic Ocean currents force upwards dissolved mineral that nourishes the marine organisms of the Hebridean fringe. From this rich cold water, calcium carbonate is extracted, not only by invertebrates to make their shells, but also by the calcareous red algae, Phymatolithon and Lithothamnion coralloides, collectively known as ‘maerl’. Found at depths of between 10m and 18m, living maerl beds produce small granules between 2mm and 10mm in size that accumulate in beds and which grow at 1mm a year. Sorted by currents and eventually washed landwards … Read More
Landis Wofford (USA) Like all mountains, the Blue Ridge Mountains of western North Carolina and Eastern Tennessee are the result of the action of plate tectonics. The crust of our planet is composed of five primary plates, or huge pieces of rock that move very slowly over deeper layers of hot, pliable rock. Some of the plates are composed of heavy oceanic crust, while others are made of lighter continental crust. At the middle of each oceanic plate, a large crack pours lava out onto the ocean floor. This causes oceanic plates to expand by an inch or two every year. When oceanic crust is forced against continental crust, the oceanic crust is pushed underneath the continental crust. When continental crust is forced against continental crust, huge mountains usually are formed. Fig. 1. View from the top of Grandfather Mountain. The Appalachian Mountains were formed in the remote past, some 200Ma, by collision of two continental crusts. During such mountain building, huge sheets of rock are pushed over each other. A rock layer called the Blue Ridge Thrust Sheet was moved over 60 miles to cover what is now Grandfather Mountain. These mountains were once ten times higher than they are today. Over hundreds of millions of years, erosion has carried away most of the rocks to form thick layers of sediment across the Piedmont, Coastal Plain, and in the Atlantic Ocean. Grandfather Mountain is the tallest mountain in the Blue Ridge and is now a popular tourist destination resort. … Read More
Trevor Devon (UK) Slovakia is situated at the north-western end of the Carpathian Mountains, a region well-known for its metal ore mines and quarries. One of the Sussex Mineralogical Society’s members had been a schoolteacher in Slovakia and had explored many of its mineral locations. Through his contacts there, an 11 day visit was arranged and a quite large group, comprising 17 society members, descended on the rural tranquillity of eastern Slovakia in August 2008. We were met by our two expert guides, one of whom was Dr Rudolf Ďud’a, head of the Department of Natural History in the Eastern Slovak Museum in Košice and author of the Slovakia chapter in the book Minerals of the Carpathians. Our journey took us on a round trip from eastern Slovakia up to Prešov and the Tatra Mountains on the border with Poland, across to Banská Bystrica in central Slovakia, south to šiatorská Bukovinka near the Hungarian border and back to Košice. Much of the driving was through heavily wooded mountains and attractive scenic valleys. The mines (now mostly inactive) and quarries were often well hidden, and generally required some walking (always upwards, of course) to get to from our coach. During our trip, we visited four quarries, eight mine dumps and a wooded mountainside deposit of ‘flesh opals’, so we were kept busy. One of the lasting impressions of the mine dumps (some of which were very large indeed) was the richness of secondary mineralisation – when in Cornwall, one is usually … Read More
David Bone (UK) “I have been greatly disappointed … [owing to] sand, sometimes two to three feet in thickness, or the tide not leaving the shore sufficiently exposed; so that a stranger might conclude that there were no fossils to be procured at Bracklesham”. The Sussex geologist, Frederick Dixon, writing about Bracklesham in 1850 warned readers with these words and it is no different today. Exposures of the richly fossiliferous Palaeogene sediments, which comprise the Bracklesham Group (Eocene), come and go unpredictably with the tides and weather. On a good day, extensive shell beds, around 46 million years old, cover the beach and sharks’ teeth may be found by the hundred. On a bad day, Dixon’s quote is all too true. Fig. 1. Location map for Bracklesham Bay, West Sussex. Bracklesham Bay is located seven miles south of Chichester in West Sussex, on the south coast of England (Fig. 1), at the eastern end of the syncline known as the Hampshire Basin. To the north, beyond Chichester, the ground rises to the Cretaceous chalk hills of the South Downs, while, to the south, across the waters of the Solent, the Isle of Wight stretches across the horizon. It is often said that if you can see the Isle of Wight, it is going to rain. If you can’t see it, then it is raining. This is a fair warning to anybody planning a trip here – this balmy stretch of coast, even on a sunny day, takes the full brunt … Read More
Tim Ball (Canada) Those who I refer to as ‘the new deniers’ keep trying to repair the infamous climate “hockey stick”. This is a term coined for a chart of temperature variation over the last 1,000 years, which suggests a recent sharp rise in temperature caused by human activities. The chart is relatively flat from the period AD 1000 to 1900, indicating that temperatures were relatively stable for this period of time. The flat part forms the stick’s ‘shaft’. However, after 1900, temperatures appear to shoot up, forming the hockey stick’s ‘blade’. Those who support the hockey stick focus on the blade, but it was not the major issue originally. The bulwark claim of the anthropogenic global warm (AGW) hypothesis and the objective of the stick are that current global annual average temperatures are the warmest ever. This meant that the upturn of the blade in the twentieth century was only relevant if it was higher and steeper than any previous record. Earlier warm periods were not a threat in the first reports of the Intergovernmental Panel on Climate Change (IPCC). Their mandate required that they only look at human causes, which they interpreted to mean the industrial period. However, as experts who were denied participation in the IPCC process began to examine what was said, they identified earlier warmer periods, especially the Medieval Warm Period (MWP) dating from 900AD to 1300AD, and more rapid temperature increases. Fig. 1. Temperatures for Europe plotted against the 20th century average. (Source: Based … Read More
Stephen K Donovan (The Netherlands) Building stones may tell us something or nothing about the geology of the local area. As Ted Nield (2014) recently highlighted in his book, Underlands, stones used in Britain today are rarely local. Once upon a time, local stone would have been derived from a nearby quarry. Now, stones are commonly imported from overseas. If that is the case in the British Isles, then pity the poor geologist in the Netherlands, where genuine exposures of rock only occur in the south, in the province of Limburg, and mainly consist of Upper Cretaceous chalks and limestones. In consequence, ornamental and facing stones on buildings are almost invariably imported. I mainly have eyes for the imported Upper Palaeozoic limestones, probably mainly Carboniferous, but potentially including some from the Devonian. These rocks are common (van Roekel, 2007), but I also pay attention when I spy a beautiful granite, in the broadest sense, which are common on the fronts of banks and used even more extensive to clad offices. This article is about two such granites (out of many) cladding buildings in Noord Holland, which have particularly caught my eye. For a general mineralogical reference, I recommend Deer et al (1966). A faulted granite in Hoofddorp This site is close to the limestone street art in Siriusdreef (described by Donovan, 2014; and see also Fig. 1) and is an easy walk from Hoofddorp railway station or bus stops on the #300 express bus route. The building in question (there … Read More
For anyone like me who finds the immensity of geological time (‘deep time’) both fascinating and fundamentally difficult – both emotionally and intellectually – this is a great book.
Dr Neale Monks (UK) While they can be found in many other parts of the British Isles, Scotland is uniquely associated with Palaeozoic fossil fishes. That Scotland’s fossil fishes are so well known is largely thanks to a remarkable man from Caithness, called Hugh Miller. Where scholars had dismissed the Old Red Sandstone as lacking in fossils, Miller found many finely preserved fossil fishes. He published several books on field geology including, in 1841, his most famous work, The Old Red Sandstone. This eminently readable book described the formation in great detail and included dozens of beautiful engravings that illustrated the fossil fishes he had discovered. Fig. 1. Dipterus – Achanarras Quarry (© Dr Jens Rydell). What is the Old Red Sandstone? The Old Red Sandstone is a distinctive set of sandstone rocks dominated by sediments laid down under non-marine, relatively dry climate conditions. It is predominantly Devonian in age, though, in Scotland at least, certain parts may be as old as Middle Silurian. This makes it much older than the formation known as the New Red Sandstone, which was laid down during the Permian. Fig. 2. Milleosteus remains from Thurso. (© Dr Jens Rydell.) Geologists can find Old Red Sandstone sediments across much of the British Isles, from Cornwall in the southwest of England to the Orkney Islands off the northeast tip of Scotland. For the most part, the Old Red Sandstone is indeed red thanks to the large quantities of iron oxide it contains, but, at some localities, … Read More