Akal Wood Fossil Park, Rajasthan, India

Khursheed Dinshaw (India) The Akal Wood Fossil Park is located about 18km from the desert city of Jaisalmer in Rajasthan, India. It has preserved fossil evidence dating back to the Jurassic Period (Fig. 6) indicating a hot and humid climate characterised by dense forests. In particular, 180-million-year-old fossils of animals and plants are preserved here. Fig. 1. The fossilised logs have been protected by iron grill cages with overhead tin sheds. The Jaisalmer Basin formed part of the southern shelf of the Tethys Ocean during Jurassic times. The area is well known for its rich geo-diversity, both in terms of landscapes and outcrops of rock types, and the variety of fossils that these rocks have preserved. When I spoke to him, Dr Sudesh K Wadhawan, who is Adviser (Geosciences) and Visiting Faculty, Director General (Retired), Geological Survey of India, explained that, “Lithostratigraphy of the geologically mapped formations displays an array of Jurassic siliciclastic, mixed carbonate-siliciclastic and carbonate rocks that range in age from Lower Jurassic to Upper Jurassic in geological timescale. A variety of depositional environment, ranging from continental fluvial to near-shore and off-shore deep marine, are interpreted and well documented in the Jaisalmer basin”. Fig. 2. Fossilised tree trunks lying scattered in an area of 21 hectares. The fossil logs, representing gymnosperms, belong to the dicotyledonous stems of these trees (Figs. 7 and 8). (In such stems, the vascular bundles are arranged in a ring, with pith concentrated at their core, rather than being scattered throughout the plant interior.) … Read More

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Collecting sharks’ teeth at Herne Bay, Kent

Les Lanham (UK) Just to the east of Herne Bay in Kent, on the way to Reculver at Beltinge, there is a small area on the foreshore where fossils of shark and other fish remains can be found on a good low tide. As this is a beach location, success will depend on good, local conditions but, if favourable, a good number of fossil teeth can be found. In fact, Beltinge is one of the best areas in Britain to collect such teeth and it is not unusual to find 20 to 30 persons on the beach on very low tides. Even so, everybody there could end up with a good haul of material by the end of the day. Fig. 1. Four keen geological groups meet for the annual extreme low tide event. I have set out directions at the end of this article detailing where to start your day. From this starting point, go as far out as the tide will let you and shark teeth can be found. Indeed, the chances of finding teeth improve the further out the tide goes. Broadly speaking, the collecting area is in the section of beach between the groynes either side of the concrete steps. Here, when the tide has gone out quite a distance, there appears to be a “stream” running out to sea. This is the junction between the clay beds to the west and the shingle to the east. Fig. 2. Thanet Beds exposed east of Herne Bay. … 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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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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Urban geology: The Worsley Park wall game, Manchester

Stephen K Donovan (The Netherlands) Wall games are a very geological form of light entertainment and education. I certainly have amused myself by identifying rocks and their features in walls since my days as an undergraduate and before. I was introduced to the name for the wall game (obvious, I know) by Eric Robinson (1996, 1997). Eric’s examples inspired me to devise my own version of a wall game in far-flung Jamaica. At the time, I was a member of the teaching staff in geology at the University of the West Indies in Mona, Kingston. Each semester, we took the first year classes for three one-day field excursions. As cash was getting ever tighter. I hit upon the money-saving idea of running one of the first trips on campus where there were various ‘urban geological’ features worthy of note. One of these was the stone base of a ruined building that had survived from Mona’s days as a sugar plantation. The rocks in the base were a marvellous mixture of blocks and rounded boulders, presumably collected from the bed of the nearby Hope River, which drains the mountainous country to the east of the university. This trip worked well and, after a few years, the late Trevor Jackson and I published a field guide based on my excursion (Donovan and Jackson, 2000). The primary criterion for a geologically interesting and educational wall game is a good variety of rocks. The Mona wall game was most satisfactory in this respect, with … Read More

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All change at Selsey, West Sussex, UK

David Bone (UK) Issue 26 of Deposits magazine in the Spring of 2011 included my article on fossil collecting at Bracklesham Bay in West Sussex, following in the footsteps of my guide book on Fossil hunting at Bracklesham & Selsey, published in 2009. This area has been well known for the foreshore exposures of Palaeogene and Quaternary geology since the mid-nineteenth century and is still very much an area for popular fossil collecting, as well as research. Many readers will have been to Bracklesham or Selsey to collect sharks’ teeth and may have even been lucky enough to find a piece of mammoth bone or tooth. The scientific value of the area is recognised by much of the coastline being designated as a geological Site of Special Scientific Interest (or SSSI). However, this has been impacted by two major coastal defence schemes at Selsey that were completed in 2013, significantly changing access to the foreshore and any exposures of the geology, as well as rendering my guide book in need of a major update. In medieval times, Selsey was effectively an island, although this is no longer the case due to the construction of sea defences and land reclamation. However, Selsey remains a localised area of higher land surrounded by low-lying land prone to flooding (Fig. 1). It has also been an area of coastal erosion and loss of land to the sea throughout recorded history. The relatively unconsolidated Palaeogene and Quaternary sediments exposed in the low cliffs of the … Read More

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