Jon Trevelyan (UK) I had the good fortune recently and rather delightfully to spend a week on the beautiful Isle of Skye, the largest of the Inner Hebrides. The weather was surprisingly good for September and a good time was had by all. In terms of geology, there are some exceptionally old rocks on Skye. We were staying on the east coast of the Sleat Peninsula, which consists of Lewisian gneiss, which is some 2.8 billion years old, and nearby is Torridonian sandstone, which is a mere 550 million years old. There are also Triassic rocks, from a time when Skye was part of a vast desert and there are the much younger, Palaeocene rocks of the Skye volcano, whose gabbros makes up the glorious Cuillin ridge (Fig. 1). Fig. 1. A classic view of the gabbro of the mighty Cuillin Ridge. So, while I was there, I took the opportunity to leave the family in their respective beds early one morning (none of whom are really interested in geology) and drive to the little Staffin Museum (known also as Staffin Dinosaur Museum), in the northeast of the island. This also provided me with the opportunity to drive past and visit some of Skye’s other geological highlights, namely the Storr (Fig. 2), the impressive Mealt Falls cascading directly into the sea and the equally impressive Kilt Rock (Fig. 3). Fig. 2. The Storr. Fig. 3. Mealt Falls, with the basalt columns of Kilt Rock in the background. However, it is … Read More
Deborah Painter (USA) On a cool, early December day in 2020, my friend David Hawk and I decided we simply had to search for fossils after not doing so for months, and also not be stopped by the chill or the coronavirus. Rather, we would prepare for both. We set off from Norfolk, Virginia USA and drove west to Smithfield, using our GPS to find Chippokes Plantation State Park in Surry County. We found the intersection of Business Route 258 and US Route 10 west of Smithfield, and followed the latter for approximately 22km, before turning right off US Route 10, Virginia to State Route 634. From this intersection, we travelled on 634 for a few kilometres, then right onto State Route 633, and then turned left, which took us back to State Route 634. We then had to climb a steep and winding road through a forested area. “This had better be worth it”, I grumbled, mostly to myself. After about 15 minutes, we reached the intersection with State Route 665 and saw the sign for Chippokes Plantation State Park. We paid our seven dollars daily parking fee at the entrance gate and we soon found the car park for the visitors centre. A family with young children arrived at about the same time and quickly took one of the trails. The car park was only about 40 or so meters from the edge of the bluff overlooking the James River, an estuarine tributary of the Chesapeake Bay. Here, … Read More
Paul D Taylor (UK) Many fossil collectors will have been disappointed to discover mollusc and brachiopod shells ‘disfigured’ by crust-like coverings of oysters, serpulid worms, barnacles or bryozoans so firmly cemented to the shells that they cannot be removed. However, rather than discarding these encrusted shells, it is worth considering what they can tell us about the ecology of the host animals and the fate of their shells after death. Furthermore, the surfaces of the shells were battlefields for encrusters fighting for living space, allowing a rare opportunity to observe the effects of biological competition millions of years ago. The key palaeoecological advantage offered by encrusters over most other fossils is that they preserve their original life positions. For example, a fossil barnacle encrusting a fossil bivalve (Fig. 1) is located on the shell exactly where the barnacle larva settled and the adult spent its life. Encrusters are not transported or displaced from where they originally lived, although of course the shells themselves may have been moved. Fig. 1. Field photograph of two barnacles, one large and one small, attached to an articulated bivalve shell. Like other encrusters, the barnacles preserve their original life positions on the bivalve. Pleistocene, Nukumaru Brown Sand, near Whanganui, New Zealand. Encrusters are sclerobionts, a collective term for organisms colonizing all kinds of hard substrates, including shells, bones, wood, rocks and sedimentary hardgrounds (Taylor and Wilson, 2003). Other types of sclerobionts bore into hard substrates, leaving trace fossils as evidence of their former presence, or … Read More
Dr Kendal Martyn (UK) Spectacular “spiny” adaptations of the Devonian (about 380Ma) trilobites of Morocco are well known. Free-standing spines, sometimes up to one hundred on a single specimen, make for spectacular (if fragile) specimens. Historically, similar species were first recognised way back in the 1880s by the classic work of Barrande on the fossils of Bohemia (in what is now the Czech Republic). Fig. 1. Walliserops issimourensis. More recently, the large-scale commercial digging of trilobites in the Anti-Atlas of Morocco, coupled with improved preparation techniques, has produced a wealth of information and new forms. As the digging around Djebel Issimour got tougher during the mid-late 1990s, this lead to people digging further afield. Near Foum Zguid, they found something new – a trilobite with a trident. Fig. 2. Walliserops issimourensis. Now called Walliserops trifercatus (Morzadec, 2001), many features relate this trilobite to more widespread asteropygid trilobites such as Comura bultynki and Quadrops flexuosa (also known as Phyllonix phyllonix). Fig. 3. Quadrops flexuosa. Walliserops trifurcatus is hard to find: one person, one week (full time) for one specimen (often incomplete). In fact, getting hold of a complete specimen is hard: getting it out of the rock without butchering it is harder still (see an unprepared trilobite and you’ll see what I mean). Fig. 4. Walliserops sp. Debate started almost immediately on the purpose of the trident: hood ornament; antler; defensive spear; sensory organ or feeding aid. Discovery of a smaller, short-trident form at the same locality, Walliserops sp., suggested sexual … Read More
George Corneille (Ireland) I have been a collector of marine reptile and dinosaur fossils for many years and started to sell on a small scale a few years ago. This editorial is specifically to help collectors identify teeth that they may have in their collections and to better understand these giant ocean going reptiles that dominated the oceans from the middle to late Cretaceous. Many mosasaur species have been identified by isolated teeth. This is extremely difficult, because, ideally, to describe a new taxon, you need skull elements, jaw hinges, flipper digits and so on. This fossil material is of course not easily available for the most part and we have to rely on isolated teeth. However, both French palaeontologist, Camille Arambourg, and Belgian palaeontologist, Louis Dollo, have relied on isolated teeth to identify a new taxon. The first mosasaur was discovered in Holland in 1780 by Dr Johann Leonard Hoffman. Since that time, at least another 40 species have been identified worldwide from Sweden to Africa and Israel to New Zealand as well as the USA, especially in Kansas. Mosasaurs dominated the world’s oceans at the end of the Cretaceous. Here, we concentrate on the Moroccan species, specifically from the Oulad Abdoun Basin and Sidi Daoui in the Moroccan Sahara. There are currently six identified species of mosasaur from the marine deposits in Morocco. Arambourg (1952) was the last comprehensive study of marine fossils. In Mosasaurus beaugei (Arambourg 1952), the tooth crowns are described as robust with both carinae … Read More
Steven A Alter (UK) Imagine a shark three times the size of the modern Great White shark charging with reckless abandon into a pod of enormous 30 foot Sperm Whales. The mighty ﬁsh opens its gaping jaws and crunches into the side of one of the swimming mammals, slicing through ﬂesh, blubber, ribs, and vertebrae. A single 6˝ long ivory-white tooth is pried loose from the shark’s lower jaw and ﬂutters down to the bottom of the ocean, stained red from the assault. The tooth hits the bottom and soon settles down in the soft mud. The tooth is slowly covered by the sediment until it is deep enough where it is cut off from the water and any oxygen that might creep through. Ten million years later, a diver probes into the bottom of a relatively modern river and uncovers this magniﬁcent tooth, now brown from the minerals that have penetrated it over the years. This tooth, now a fossil but almost as sharp as the day it was lost, becomes a prized possession for the lucky ﬁnder who hurries up to the boat to show his friends. This tooth is from the largest predator to ever inhabit the world’s oceans – Carcharocles megalodon. Fig. 1. Carcharocles megalodon. This ancient story relives itself day after day all over the world. Evidence of the megalodon shark can be found in fossilised teeth and vertebrae (even fossilised whale bones still showing bite marks from the attack) all over the world. The … Read More
E R Matheau-Raven (UK) Amber is the hardened resin of coniferous and angiosperm trees. Resin should not be confused with sap, which is a product of photosynthesis that consists of sugars, water and dissolved minerals. The sticky extrusive mass that comes from a cut on a pine tree is resin. Under the proper conditions, it undergoes certain physical and chemical changes that turn it into amber. If resin has hardened in recent times, it is called copal. Columbia, in South America, has extensive copal deposits. Presently, certain trees produce large quantities of resin; the Kauri gum from New Zealand (Agathis australis), the Sundarac from Australia (Tetraclinis articulata), the Gum Arabic tree from Africa (Acacia arabica)and the Algarroba tree from South America (Hymenaea courbaril. It was trees like these that produced the resin that often trapped unsuspecting insects and even some slightly larger animals. Like ﬂy paper, the more the animal struggled to get free, the more entangled it became. Fig. 1. Caddis fly: Order – Diptera. Often, the origin of the amber can be derived visually from the amber itself. Baltic amber may have a cloudy appearance, due to air bubbles and also has a high percentage of Succinic acid, as much as 8% by weight. It is a high-molecular compound of organic acids and has been produced as a result of fossilisation of the resin from the pine, Pinus succinifera. This tree was prospering in the Baltic area 40 to 45 million years ago. Fig. 2. Ant (worker): Order … Read More
S M Bowerman (UK) Sharks of the genus Hexanchus belong to the family Hexanchidae and are more commonly known as six gilled sharks or cow sharks. They are well known for the difference in shape between teeth of the upper and lower jaw. They are first recorded in the Jurassic. Smart (2001) states that Hexanchidae are represented in the English late Cretaceous by two species: Hexanchus microdon and H. gracilis, both species being known only from rare isolated teeth. I collected a single specimen of H. gracilis, which is the subject of this short article. It was found at Hunstanton, in Norfolk in the UK (TF 673414), from the Upper Cretaceous Lower Chalk, Middle Cenomanian, Varians Chalk, Schloenbachia varians zone. Fig. 1. The striking cliffs at Hunstanton (picture courtesy of Andrea Clark). It is an incomplete specimen from the lower jaw. The specimen shows only two cusps of a possible seven. These appear to be accessory cusps. The posterior aspect of the specimen is not preserved therefore the principle cusp is not seen. The cusps show no signs of serration and the specimen remains in chalk matrix with the lingual aspect uppermost. The root is rectangular and slightly convex. Tooth width is 5mm, and its height is 3mm. Fig. 2. Hexanchus gracilis (Ref. No. H/619). Further reading Fossils of the Chalk: Palaeontological Association Guide No 2 (2nd edition), edited by Andrew B Smith and David J Batten, The Palaeontological Association, London (2002), 374 pages (Paperback), ISBN: 0901702781 References Smart, P. … Read More
Alister and Ian Cruickshanks (UK) During the year of 1818, a nugget of gold weighing around ten pennyweights was discovered in the river Helmsdale, in Northeast Scotland. The ﬁnd sparked national interest and the Scottish local newspapers were soon headlining the discovery. It was then in 1968 that Scotland ensured its place in the history books following the discovery of further gold nuggets at Kildonan, in the river Helmsdale by a local man Robert Gilchrist, who had spent 17 years in the gold ﬁelds of Australia. Fig. 1. Gold panning at Baile an Or. Gilchrist was granted permission from the Duke of Sutherland to pan the gravels of the river Helmsdale. Shortly after, word started to spread into London and, within just six months, over 600 people made their way to Kildonan, creating its own miny gold rush. A whole series of temporary living quarters started to appear along the riverbanks forming the small town, Baile an Or (meaning ‘Village of the Gold’). Fig. 2. The equipment you will need. Today, Baile an Or (Grid Reference: NC 91136 21380) continues to provide fun for all for those wishing to try their luck at gold panning. The original nugget from the river was said to have been made into a ring and is in possession of the Sunderland family, but there have been recent stories too of a couple who panned for gold twice every year over a number of years, who had their wedding ring made from the gold of … Read More
E R Matheau-Raven (UK) Florida has one of the world’s richest fossil deposits of both terrestrial and marine origin, encompassing over 2,000 known fossil locations. The state is famous for its Pliocene/Pleistocene fossil fauna but also has a rich and diverse Miocene heritage, plus its coastal waters abound with giant Carcharocles megalodon shark teeth, much prized by fossil divers for their value. Fig. 1. Tapir lower jaw. The Thomas Farm site in Gilchrist County, North Central Florida has the largest Miocene mammal deposits east of the Rocky Mountains. It was discovered in 1931 after locals reported what they thought was an Indian burial site and has, for the last 70 years, continually given up its secrets. The fossils from here are dated at 18 million years old and are typiﬁed by many types of mammal, such as the early three-toed horse Nanippus. Fig. 2. Horse upper molar: Equus sp. Florida began to form by a combination of volcanic activity and marine deposition along the northwest portion of Africa over 500 million years ago during the latter part of the Cambrian Period. At about 300 million years ago (during the Upper Carboniferous), the time of the formation of the supercontinent, Pangaea, Florida was sandwiched between what were to become North and South America and Africa. Near the Triassic/Jurassic boundary (210 million years ago), Pangaea began to divide into two major continents, Laurasia (North America, Europe and parts of Asia) and Gondwana (South America, Africa, India, Australia and Antarctica). Fig. 3. Tapir … Read More
Patricia Vickers-Rich , Peter Trusler, Steve Morton, Peter Swinkels, Thomas H Rich, Mike Hall and Steve Pritchard (Australia) The “road map” allowing (time) travellers to move across more than 1,000 million years in Namibia is recorded in the rocks of this land. And, it is on display in several museums in Namibia – in Swakopmund, Windhoek, Rosh Pinah and Farm Aar. The old part of the road In drafting the early section of this map, Southern Namibia has been a key region for understanding some of the sights our time traveller will come into contact with, some being the weird organisms called Ediacarans. Since the early days of the twentieth century, when geologists, such as Paul Range, and German soldiers occupying isolated outposts in the Aus region of Southern Namibia, some of these strange fossils were reported. These were the first ‘large’ multicellular organisms that prospered on planet Earth before the development of true animals, and amongst them were the tiny cloudinids. Their fossils are preserved in the thick rock sequences that can be seen along the “time road” in Southern Namibia. These showcase a time in the history of life when there were fundamental and pivotal changes in life occurring, with life transitioning from an enigmatic biota to what we consider normal today. And, at a number of museums in Namibia, including the Swakopmund Museum and the Namibian Geological Survey in Windhoek, several of these intriguing organisms are on show – such as the soft-bodied Ernietta, Pteridinium and Rangea,and … Read More
Deborah Painter (USA) I am an ecologist and general environmental scientist, specialising in transportation, energy and industrial development planning to minimise deleterious environmental impacts. I live in the United States and have also written several articles for this magazine. I appreciate just how important local geology and soil science are in one of the aspects of work I do: researching and writing National Environmental Policy Act documents. This is the third of three articles on how environmental scientists apply this knowledge. Part 1 detailed geology and the hazardous materials site assessment of a property (Fig. 1; see Environmental scientists and geology (Part 1): The first phase of an environmental geology investigation). Part 2 dealt with wetland and water permitting and how geology is important in that process (Fig. 2; see Environmental scientists and geology (Part 2): Geology and soil science in the ‘Wetlands and Waters Permitting’ process in the USA). Fig. 1. Hazardous material releases can have a tremendous impact and must be documented along with plans for remediation. (Credits: Deborah Painter.) Fig. 2. If wetlands are to be impacted, permits must be obtained, along with avoidance and minimisation measures put in place. The impacts must not be significant ones. (Credits: Deborah Painter.) Both of these areas of environmental due diligence are parts of every National Environmental Policy Act document, or “NEPA” document. When I write one of these, I must thoroughly document that these two potential issues – and twenty more – have been examined, and that any remediation … Read More
Ken Brooks (UK) The beach from Rocka-Nore to Pett Level is rich in fossil evidence. Even the most insignificant fossils are important because they provide clues that enable us to reconstruct the ancient environments of this area. Between 100 and 140 million years ago, much of southern England was covered by lakes and lagoons. Rivers flowing from the London area and the west deposited great quantities of sand and silt on extensive flood plains. Molluscs, fish and freshwater sharks lived in the lakes and rivers, while the land was dominated by crocodiles, turtles and dinosaurs. Fig. 1. The Hastings coastline today. Eventually, their fossilised shells, scales, teeth, bones and footprints were preserved in the layers of sediment. Carbonised plants, such as horsetails, ferns, cycads, conifers and tree ferns, indicate that the summers were hot and dry (with frequent fires), followed by wet and humid conditions in wintes. Millions of years later, when Africa collided with the European plate, southeast England was pushed upwards into a vast dome-shaped structure, known as the ‘Wealden anticline’. Since then erosion has removed many layers of rock and exposed the sandstones and clays which now form the cliffs between Hastings and Pett. Fig. 2. Hastings during the Lower Cretaceous (© Stuart Handley). Bones and footprints of Iguanodon are among the most common dinosaur remains, although other very interesting fossils have recently been found in the Hastings area. These include the spines and vertebrae of Polacanthus, a tooth from Baryonyx and quillwort plants still in their … Read More
Alister Cruickshanks (UK) The Norwich Crag at Easton Bavents, Southwold in Suffolk is one of the only locations where mammalian remains from the Pleistocene Epoch can be found, in situ, at an accessible location in the UK. The Norwich Crag splits the Antian and the Baventian. At Easton Bavents South Cliff, the Norwich Crag Shell Bed is missing. Instead, there is a ﬁne gravel layer with laminated clay and sand, which yields occasional remains. This bed is equivalent to the Lower Shell Bed of the North cliff at Easton Bavents, One of the latest theories suggests that this was once a pre-historic fast ﬂowing river, which ﬂowed into a larger estuary that was present at the North Cliff during the Pliocene Era. The North Cliff itself has a stone layer above the Norwich Crag Shell Bed. This bed comprises three main bands: the upper, middle and lower beds, but varies considerably along this stretch of cliff. The Norwich Crag Stone bed is directly below the Baventian Clay, both of which are from the Baventian stage which is 1.55 to 1.6 million years old, from the Pliocene Era. The Norwich Crag Shell Bed is Antian in age, which is 1.6 to 1.7 million years old. Fig. 1. Fine gravel layer with laminated clay and sand. A complete lower mandible of a walrus was discovered in situ after high tides during 1993, by my father and me. At this time, the specimen could not be fully identiﬁed and spent ten years at … Read More
Mike Thorn (UK) If you ask someone to think of Oxford, they will not usually picture warm tropical beaches and azure coral seas. However, go back to the middle Jurassic and you would be hard pushed to find a dreaming spire or student on a bicycle anywhere. At that time, around 160 million years ago, Oxfordshire lay beneath a shallow, tropical seaway at about the same latitude that the southern Mediterranean occupies today. Over the course of the middle Jurassic, this seaway varied in depth, but remained close to nearby land masses from which a lot of sediment was derived (Fig. 1). A great thickness and variety of limestones, sandstones and clays were deposited over several tens of millions of years. Fig. 1. Southern England during the middle Jurassic, 160 million years ago. During the nineteenth and early twentieth centuries, there were many working quarries in the Oxford area, exploiting the abundant clay and limestone for the brick and building stone industries. Quarrymen were frequently paid to look out for fossils and these turned up in abundance, fuelling the academic debates on evolution taking place at the time. Fig. 3. Geological Context for Kirtlington Quarry and Dry Sandford Pit. Sadly, many of these quarries have now been filled in and, for the casual fossil hunter in Oxfordshire, it might seem that there are now few opportunities to collect. However, Kirtlington Quarry and Dry Sandford Pit are two old quarries which are open to the public and at which there is … Read More
Ken Brooks (UK) This is the first of three articles on the geology and fossils in the cliffs and foreshore to the east of Hastings. This one is intended as a field trip. The geology here is all Lower Cretaceous and is some of the best in Britain if you are interested in this period of time. Follow the Hastings seafront eastwards to the ‘Old Town’ and the famous ‘net shops’ in Rock-A-Nore Road. Below the high, sandstone cliffs of the East Hill, you will find the Fishermen’s Museum, the Blue Reef Aquarium (a sea-life centre), a large car park and public toilets. This field trip begins at the last stone groyne and continues along the beach towards Ecclesbourne Glen, nearly one kilometre (half a mile) to the east. The massive sandstone cliffs of the Upper Ashdown Formation are overlain by the shales and sandstones of the Wadhurst Clay. A distinct junction between one horizontal bed of rock and another often marks a period of erosion. This may have been followed by a change in the environmental conditions where a different grade or type of sediment was deposited. In this area, the lower part of the cliff is hidden under a scree slope of broken rocks, but there is one small exposure in situ at beach level. Here, there are flattened branches of carbonised wood lying horizontally within a silty mudstone. These were probably washed into a river or lake, then later covered and compressed by sedimentary layers. The leaves … Read More
Deborah Painter (USA) I am an ecologist and general environmental scientist specialising in transportation, energy and industrial development planning to minimise deleterious environmental impacts. I live in the United States and have also written several articles for this magazine. One of the things I really appreciate is just how important local geology and soil science are in one of the aspects of work I do: delineating wetlands and obtaining permits from regulatory agencies for work in wetlands and waters. This is the second of three articles on how environmental scientists apply this knowledge. The first is entitled Environmental scientists and geology (Part 1): The first phase of an environmental geology investigation. The discharge of dredged or fill material into waters of the USA and most categories of work in navigable water bodies require US Army Corps of Engineers authorisation under Section 404 of the Clean Water Act of 1972. These activities also require Section 401 Clean Water Act permits from their state governments. The Federal definition of “waters of the United States” includes rivers, small streams, bogs, most nontidal wetlands, many lakes, mud flats, bays, the US territorial sea, and even many drainage ditches (Figs. 1, 2 and 3). They do not include isolated, nontidal wetlands with no connection to interstate commerce. However, a state may assert jurisdiction over these isolated wetlands under its Section 401 program, if it chooses. Fig. 1. In New York State, northern white cedar (Thuja occidentalis) is a common nontidal wetland tree. (Credits: Deborah Painter.) … Read More
Dr Kendal Martyn (UK) This article describes several processes producing the shape of crystals. Such processes are illustrated in the most common mineral from the Earth’s surface, quartz. Quartz or “simple” silicon dioxide, is made up of interlocking atoms of silicon and oxygen, arranged into various symmetrical structures depending on pressure and temperature conditions. Such variation in the structure accounts for most of the different minerals discussed below. The presence of these different SiO2 minerals in rocks gives important information about the conditions those rocks were exposed to. Starting rules Minerals are classified by their distinctive structure (atomic arrangement), as well as their chemistry: all the mineralsdescribed below have the same chemical composition but different physical forms, known as polymorphs.Different physical structures are favoured by specific conditions of temperature and pressure (Fig. 1).If conditions favour a change in structure, the old structure may be preserved or a new structure formed,depending on the amount of energy available, the energy needed to make that change and the time available to make that change. Quenching (very rapid cooling) may “freeze in” the old structure. Kinetics (the physical re- arrangement of atoms and bonds) triumphs over thermodynamics (theoretically the energetically most favourable structure).Fig. 1. Diagram showing the stabilities of some (not all) of SiO2 polymorphs under different temperature and pressure conditions. (From the Cambridge University website.) Breaking and reforming atomic connections, a radical rearrangement, needs more energy and requires material to diffuse across the crystal. Such reconstructive transitions will only happen if there is … Read More
Ken Brooks (UK) During the Lower Cretaceous period, between 110 and 145 million years ago, Britain was part of the European land-mass. Southeast England was covered by meandering rivers, extensive ﬂood-plains, lakes and lagoons which extended across to central France. Rivers ﬂowing from the London Uplands and the west brought huge quantities of sand, silt and mud, which were deposited over the whole area. Fig. 1. Starlight Cove These sediments later became the sandstones and clays of the Ashdown Sandstone and Wadhurst Clay within the Hastings Beds. Structures in the rocks, combined with fossil evidence, can be used to reconstruct the ancient environments and communities of this period. For example, the siltstones, clays and sandstones have preserved features such as river channel and ﬂood plain deposits, as well as a rich variety of fossilised plants and animals. Fig. 2. An infilled river channel. The carbonised remains of horse-tails, ferns, cycads, conifers and tree-ferns indicate that Southern England had a sub-tropical climate with seasonal rainfall, perhaps like the Mediterranean today. Freshwater sharks and shellﬁsh lived in the lakes and rivers, while the land was dominated by crocodiles, turtles and dinosaurs. Today, their scales, teeth, bones and footprints may be found along the stretch of beach between Rock-a-Nore and Pett Level. Fig. 3. Crocodile tooth: Goniopholis. Around 100 million years ago, the great weight of the sediments, combined with geological faulting, resulted in a gradual subsidence of the southeast. As a warm, shallow sea began to cover most of England and northern … Read More
The second edition of this guide is written to explain the key concepts of tectonics and rock structures to students and to interested amateurs. I have reviewed a number of Graham Park’s books in recently years (see below) and he is clearly a prolific and excellent writer of books about the earth sciences.
Tony and Anna Gill (UK) The best time to look for fossils in Dorset is after heavy rain and winter storms. These conditions make the cliffs unstable and collapse. High winds produce rough seas, which wash the mud away, leaving the nodules that contain the fossils exposed on the beach. The beginning of November 2005 saw a period of heavy rain and strong winds. This stormy weather continued for several days and on 5 November gale force 10 winds, before a high tide, exposing new material (Fig. 1). Fig. 1. A large landslip, approximately four hundred metres east of Charmouth, contains most of the best fossil horizons. This slip is illustrated with the sea crashing into it (Fig. 2). The large stones in the picture below do not contain any fossils. If they did, they would not be there. The best place to look for smaller fossils is around these large stones. Some of the pyrite ammonites found here can be up to 25cm to 30cm in diameter. Fig. 2. The storm crashing against the cliffs at Charmouth. The flat stones, which are from the Obtusum Shales, sometimes contain the ammonite Asteroceras Planicosta and usually the smaller ammonites Promicroceras Planicosta (Fig. 3). Fig. 3. Charmouth was the seabed in Jurassic times, some 195 million years ago. The football shaped and sized, Stellare Nodules, when broken, contain calcite crystals. Occasionally though, an ammonite can be found inside the larger ones. These ammonites can be up to 50cm across, but unfortunately, most … Read More
Dr Richard J Hubbard (UK) Introduction The Thanet Anticline is an uplifted area forming the northeast corner of Kent and is home to the four coastal towns of Birchington, Margate, Broadstairs and Ramsgate (Fig. 1). Historically, the area has been known as the Isle of Thanet and, in this article, I will look at sediment deposition and erosion around the upstanding anticlinal structure and how shorelines have shifted during the past two thousand years. I will finish with some thoughts about how shorelines might look one hundred years from now. The article is based on material drawn from three guidebooks published by GeoConservation Kent, written by Geoff Downer and myself (see below). Fig. 1. The Isle of Thanet. Sketch map of northeast Kent to show the geography of the Wantsum Channel at the time of the Roman occupation. Today’s shoreline is superimposed with some medieval settlements added for orientation. The Isle of Thanet is elevated and forms an ‘island’ because of the underlying structural geology. Note the location of the offshore seismic line published by Ameen (1995), on which the cross section of Fig. 4 is based. (Figure 87 from The Smugglers Trail, Hubbard & Downer, 2021.) This article has also been written to accompany a book review that was recently published by Deposits (see Book review: The Smugglers Trail – Geology of the Thanet Coastline from Broadstairs to Cliftonville, by Richard Hubbard and Geoff Downer). Thanet has been a high standing area for more than 300 million years and … Read More
Helen Gould (UK) Chemistry is the key to identifying the source of a meteorite. The commonest rock in the Solar System – and on Earth – is basalt. Erupted at mid-ocean ridges and many hotspot volcanoes, it also floors the oceans. However, each of these situations can be identified as geochemically different from one another. Some meteorites have geochemical signatures associated with individual asteroids, being either enriched or poor in specific minerals. The ratios of their minerals are plotted against one another, then the shape and co-ordinates of the plots are cross-referenced to a database. This process has allowed distinct groups of meteorites with similar geochemistry to be identified, suggesting that the meteorites in each cluster plotted came from the same source. There are five sub-groups of achondrites of various chemical composition, including eucrites, diogenites, SNC, lunar achondrites and ureilites. The name means they don’t contain chondrules. Most are of igneous origin, but lunar achondrites resemble fragmental sedimentary rocks. The only “weathering” on the Moon comes from impacting meteorites, but this breaks up rocks and reforms them into breccias – jumbles of jagged fragments fused together. Eucrites Eucrites are basaltic meteorites containing low-calcium proxenite and plagioclase feldspar with metallic iron, troilite (iron sulphide) and silicates. They probably all crystallised at or just below the surface of their source bodies. Fig. x. Eucrite. Diogenites Diogenites consist of calciumpoor pyroxenite, which is an igneous rock resembling the ocean crust. Fig. x.. Diogenite. SNC SNC meteorites have been identified as coming from Mars. … Read More
The Crowood Press are really developing a nice little series of books on the landscape and geology of select regions of the British Isles, and Tony Waltham’s addition to the series about the Peak District is well worth a read. This new one follows the same format as the others – beautiful, full colour photos and diagrams, a fascinating chapter on each of the important geological and geomorphological aspects of the area (including buildings and industry), and an author who knows his stuff and can write it down with an easy and authoritative style.
Thomas H Rich and Patricia Vickers-Rich (Australia) Whether they had horns or not, the ceratopsian “horn faced” dinosaurs are distinctive, not only from other dinosaurs, but all other vertebrates as well, in the structure of their skulls. In addition to the horns, another element of their skeleton, the lower arm bone (called the ulna or elbow bone), unexpectedly is so distinctive that it has provided clear evidence that, 130 million years ago, these very ceratopsians were living in Australia. Prior to that discovery, the ceratopsians were known almost exclusively in the Northern Hemisphere. Just over a century ago, a toothless lower jaw found in Patagonia, Argentina was named Notoceratops, “the southern horned face”. The last time that fossil was seen was a decade later when the world-renowned dinosaur authority, Fredrich von Huene, studied and redescribed that fossil and agreed unreservedly that it was a ceratopsian. Illustrations of that bone strongly support its correct identification as a ceratopsian. However, unfortunately, von Huene is the last person known to have laid eyes on it, and the fossil cannot now be found. Thus, the only ceratopsian previously thought to have come from the Southern Hemisphere, disappeared. When the Victorian dinosaur ulna, which is the subject of this article, was first found at the base of the Arch near Kilcunda (Fig. 1) by Mike Cleeland, Tom’s first guess was that it was some kind of carnivorous dinosaur or theropod. This was because it was a short, stumpy bone, which is so characteristic of the … Read More
Deborah Painter (USA) I am an ecologist and general environmental scientist living in the USA and specialising in transportation, energy and industrial development planning to minimise deleterious environmental impacts. I have also written several articles for this magazine. As such, I appreciate just how much local geology is a vital consideration in many circumstances and especially during one of my routine responsibilities – undertaking a Phase I Hazardous Materials Site Assessment of an industrial or commercial property in the United States. This is the first of three articles on how I and other environmental scientists apply our knowledge of geology in our day to day work. But what is the purpose of these assessments? Companies such as my employer do these to benefit a person or business desiring a loan from a bank to purchase a property or to pay for upgrades. Cities and counties also contract with environmental companies for Phase I Environmental Site Assessments for properties they own and want to improve, or intend to acquire for resale to private parties. For example, city officials may have their eyes on an old former school and grounds as the future site for a new police station, and want to know how expensive it would be to renovate it as opposed to demolishing it to build a new structure. The assessment is done to satisfy the current American Society of Testing and Materials (ASTM) Standard E 1527-13: Standard Practice for Environmental Site Assessments (2013), and the United States Environmental Protection … Read More
This is an ambitious little field guide, which aims to allow amateurs to identify basic rocks and rock formations, for the first time, in a systematic way., as it says: “… using only careful observation, a magnifying glass, a pocket knife – and a bit of patience”.
Stephen Moreton (UK) Our journey around Ireland concludes in Ulster. This comprises Northern Ireland, which is part of the UK, and the counties of Cavan, Donegal and Monaghan, which are part of the Republic of Ireland. As geology is no respecter of politics, the national border is ignored here. I assure my gentle readers that this is not intended as a political statement! The geology consists of metamorphic rocks and granite intrusions in the west, a huge expanse of Tertiary basalt in the eastern half, and a series of Tertiary granite intrusions in the southeast corner. Carboniferous limestone makes an appearance in some places, but is not as well endowed with minerals as further south. Fig. 1. The four regions of the island of Ireland. Fig. 2. Ulster in more detail. Donegal, occupying the northwest corner of the island, has such a varied geology that it has long been a favourite venue for university ﬁeld trips. In spite of this variety, there are few mining sites. Lead has been mined at Glenaboghil, Keeldrum and Glentogher, but these old mines are not noted for specimens. However, minor yellow powdery greenockite occurs at the ﬁrst location and green coatings of pyromorphite at the second. What it lacks in mines, the county makes up for in silicate minerals. The beryl occurrence at Sheshkinnarone is probably the best known. Finger size green and blue-green prisms in a white quartz matrix occur at several spots here. The richest is just outside the garden wall of … Read More
Helen Gould UK) What are meteorites? Lumps of rock left over from the formation of the solar system or “chipped off” planets during major impacts can become trapped in the Earth’s gravitational field and fall as meteorites. The three main types are iron, stony and stony-iron. All of these are discussed in this article. In particular, I consider two important questions: Why are they so important? Because they represent the growth (accretion) of planets, they carry clues to our Solar System’s formation.How do we know we are dealing with a meteorite? Like other rocks, meteorites record events. Most of their minerals are familiar but some have higher or lower concentrations than rocks found on Earth, suggesting an extra-terrestrial origin.Irons Fig. 1. Iron meteorite. Most contain 7-15 wt % of Nickel (Ni) metal, with traces of other minerals. At room temperature, instead of a single mineral, this forms a Widmanstätten structure, whose intergrowth lamellae show two different minerals, one with about 40% Ni, the other with only about 5% Ni, and indicate slow cooling from greater than 700°C. Iron (Fe) meteorites have usually been completely melted, proving they formed in asteroid cores. So even asteroids are differentiated – like the major planets – with a core and mantle which solidified slowly. Widmanstätten patternsAlso known as Thomson structures, these are figures of long nickel–iron crystals, found in the octahedrite iron meteorites and some pallasites. They consist of a fine interleaving of kamacite and taenite bands or ribbons called lamellae.Stony-irons Stony-iron meteorites probably … Read More
I like local geological guides, which aim to get you out and about, visiting areas you might not have known are worth a daytrip. And this is a good example. I sat down and read it cover to cover, as it is only 90 pages long. And I now really want to visit this bit of Kent coastline. Largely concentrating on the Upper Cretaceous Chalk, this guidebook explains and illustrates what seems to be some marvellous geology that can also be explored during what could be a lovely day out on the beach.