ukafh
UKAFH field trip to Withington, near Cheltenham, Saturday 5th October 2019
UKAFH hosted its largest field trip ever on Saturday 5th October when we welcomed 50 members, many of them new joiners, to privately owned ploughed farm fields near Withington which we had obtained permission from the landlord to visit. The proximity of the topsoil to the Inferior Oolite below in this locality means that ploughing brings rock to the surface which contains a large variety of fossils. A field hunt (with landlord permission) really is an excellent way to find fossils with little effort other than to look patiently and “get your eye in”. It is comparatively easy to find rocks on the surface of the topsoil and inspect them for fossils, many of which are already loose from the rock. No tools or equipment are required other than a container for your finds and, at this location, a bucket was ideal as fossils were plentiful and they are easy to carry and drop the robust fossils into as you go along.
The weather conditions were dry and overcast, making it an ideal day to fossil hunt as the rock was relatively clean and easy to spot so plenty of finds were made.
The Cotswold Escarpment rocks are almost exclusively marine and were deposited mainly in warm tropical seas. Plate tectonics has transported this part of the Earth’s crust northward over the last 150-200 million years to its current location. The Middle Jurassic rocks here are the characteristic ‘Cotswold Limestone’; soft, yellow, sandy limestone at the base of the Inferior Oolite (literally egg stone), a sedimentary rock formed from ooids, spherical grains composed of concentric layers. Towards the top of the Inferior Oolite the limestone becomes more fossiliferous and is referred to as ‘grits’ due to its coarser texture. Such an Inferior Oolite exposure is exposed at the farm and the fossils that this limestone contains date from between 167 to 175 million years ago at a time when this farm was at the bottom of a warm tropical sea. The rocks exposed near the farm comprise the Salperton and Aston Limestone and, from a fossil perspective, the most interesting layers are the Grits (Clypeus, Upper Trigonia Grit and Lower Trigonia Grit), named from the index fossils found in those rocks.
The commonest fossil found at this location is the sea urchin (echinoid) Clypeus ploti. These are more commonly known as Chedworth Buns (after the nearby village where they were often found) or Pound Stones, because their weight was usually a good approximation to 1lb. Clypeus lived in burrows on the seafloor, and burrowed their way through the sediment to get nutrients. They had fine hair-like spines and are an example of what is known as an “irregular” echinoid because they are shaped, not rounded. Because these irregular echinoids lived in the sediment, they didn’t need the spiky and sometimes poisonous spines that the spiny sea urchins (known as regular echinoids) that we can see on the seafloor today have for protection. As well as the Clypeus Ploti we find other echinoid species which are “regular” and would have had sharp spines. Unfortunately the spines rarely fossilize still attached, but they can frequently be found individually in the same sediment.
Brachiopods are bottom dwelling marine animals and, although rare today, in Jurassic times they dominated the sea floor and were frequently found in large colonies. One characteristic unique to brachiopods is the pedicle, which is a long, thin fleshy appendage which is used to burrow into the sea floor as an anchor while the brachiopod could feed clear of the silt. Although the fleshy pedicle itself does not preserve in the fossils, the opening at the top of the animal from whence the pedicle connected (known as the foramen) is clearly visible. Brachiopods are filter feeders, gathering microscopic organisms and bits of organic matter from the water that flows by them using a specialized organ called a lophophore. This is a tube like structure with cilia (hair like projections). The cilia move food particles down the lophophore to the mouth.
Bivalves include such animals as clams, oysters, cockles, mussels, and scallops are also found at Withington. The majority are filter feeders and often they bury themselves in sediment where they can be safe from predators. Others lie on the sea floor or attach themselves to rocks or other hard surfaces, a few such as scallops are able to propel themselves through the water. The shell consists of two usually similar valves, and is joined at the hinge line by a flexible ligament with interlocking teeth on each valve. This arrangement allows the shell to be opened and closed for feeding without the two halves becoming disarticulated. Bivalves found here include Thracia (a member of the clam family) and Pleuromya (a member of the mussel family).
UKAFH would like to sincerely thank the landowner for allowing us access to the fields. Special thanks also to Mark Baggott for organising the visit and providing a fantastic display of local fossils and information for us all to refer to throughout the day. Thank you also to Mark and to Alan Banyard for bringing along some very nice examples of undamaged and prepared Clypeus ploti and ammonites from nearby locations for members to take home and to Andy Crawte and Alan Banyard who gave their time to assist our attendees in identifying their finds.
All in all we had a great day out and it was wonderful to welcome so many enthusiastic new members and see so many families enjoying what was for many of them their first fossil hunt. Everyone went away with finds and I saw many happy smiles! This is exactly what UKAFH is all about and I really hope we see many of you on future fossil hunts. Our 2020 hunt calendar has now been published so please take a look and I hope to see you all soon!
UKAFH Weekender – Isle of Wight 2018
On 14 and 15 April 2018, UKAFH conducted its first weekend event of the year. UKAFH members from across the UK left the mainland behind and sailed across the Solent to the sunny and highly fossiliferous shores of the Isle of Wight.
On Saturday, 14 April, we descended onto Thorness Bay, which is on the north coast of the island. Access to the bay is through Parkdean Thorness Bay Holiday Park, where many of the group were staying in caravans or, the bravest amongst us in tents. The park has excellent facilities, such as toilets, and a bar and restaurant, as well as ample parking and a small supermarket, which made it a very comfortable start to the day.
The weather was glorious and sunny – the first really warm and sunny day of the year, which filled us with hope and anticipation. In fact, we couldn’t have hoped for better or more relaxing weather.
We began in the car park, where Chris Tait and Nicky Parslow displayed some of the fossils that we were likely to find from the Oligocene epoch, such as carapaces from Emys and Trionyx turtles, and scuta from Diplocynodon alligators. We also saw shiny fish bones and vertebrae, and the very rare mammal teeth of Elomeryx – a stout hippopotamus/pig like creature. In addition, we saw echinoids preserved in flint, which can be found derived from the much older Cretaceous sediments.
We walked as a group down the gentle slope from the carpark to the beginning of the bay, where Chris pointed out the Bembridge Insect Beds to the east and where, unfortunately, fossils are few and hard to find. So, we set off to the west, where we could see a gently sloping shingle beach, with some exposures of green/blue clay from the highly fossiliferous Hamstead Beds. Chris explained to us that the best collecting technique is to look carefully and move slowly, and that moving the gravel with a trowel would likely result in uncovering fossils. Chris also painted a picture of what Thorness Bay might have looked like during the Oligocene epoch, about 30 million years ago – a lagoonal area within an estuary, where alligators, turtles and fish would have swum and hunted. Elomeryx porcinus would have been seen grazing on the edge of the lagoon and also swimming out to eat the plants growing in the lagoon. It would have been much warmer during the Oligocene, averaging 20 to 25oC, as the location lay much further south, closer to the equator.
As we headed west, we found that the first part of the bay was less productive than further along, but most people found gastropods, bivalves and fragments of turtle and fish during the early part of the hunt. As we moved along the bay, the first major find was found by UKAFH leader, Elliot Mills, who found a rare E. porcinus tooth and a fish vertebra on the surface of the shingle, within a few centimetres of each other. The group continued to round the first two corners, where more and more fossils were found. Silas Shaul found a beautiful echinoid preserved in flint, high up on the tide line. As pointed out above, this would not have come from the Oligocene epoch, but from the much earlier Cretaceous period. Isabella Rice found part of a Diplocynodon alligator scute and Nicky Parslow found part of an alligator jaw.
As the afternoon drew late, we ambled back to the holiday park and got cleaned up before the evening’s entertainment. At 7pm, we met up in the bar area of Parkdean and, at 7.30pm, Aidan Philpott presented a quiz to four teams. This was quite challenging, but fun at the same time, and there were several prizes, which were distributed for achievements, such as the Best Team Name – “The Not Crocodiles” and the Best Wrong Answer – “Strawberry Daiquiri” in answer to the question “What Beverage is Sir Hans Sloane often credited with having introduced to the UK?” (The answer is actually hot chocolate.) The Yan family won the quiz with a fantastic score of 15 and claimed the golden hammer.
After the success and glorious weather of Saturday’s hunt at Thorness Bay, we met on a drizzly Sunday afternoon at Brook Bay on the west coast of the island.
The cliffs and foreshore at Brook Bay represent part of the Wessex Formation, which is a mixture of mudstone, sandstone and clay. This was deposited during the Barremian age of the Cretaceous period, about 127 million years ago, in what was a large river basin that drained the surrounding hills. At the time, the climate here was warm and intensely seasonal. This intense seasonality is key to understanding the type and abundance of fossils found here. The landscape would have had rivers and tributaries running throughout it, with ponds, lakes and boggy areas – notable in the fossil record by the abundance of fresh water bivalves and fish remains. The water source and warm climate meant the area was, for much of the time, densely vegetated – the abundance of plant fossils here is immediately noticeable in the form of black, shiny lignite that litters the beach.
The dense vegetation would have attracted herbivorous dinosaurs, such as huge iguanodonts, sauropods and the heavily armoured Polacanthus, and the presence of herbivores would have attracted carnivores, such as the enigmatic allosaurid, Neovenator salerii (the bones of which can be seen at the Dinosaur Isle museum at Sandown). These dinosaurs left their footprints in the mud surrounding the rivers, ponds and lakes. The dry season then came, rivers ran dry, ponds vanished and lakes became anoxic, with the footprints left in once soft muddy sediment becoming solidified among a parched landscape. Charcoal derived from brush fires found in the Wessex Formation, indicate just how intense the dry seasons would have been. The wet season then followed, which is key to understanding the abundance of fossils here. Intense storms would have caused massive flooding, rapidly depositing sediment in the area, burying plant remains, bivalves and bones, as well as filling the dinosaur footprints with coarse sediment, forming casts of the footprints. Brook bay is famous for its dinosaur foot casts, which, after scouring conditions, can number in the hundreds along the beach.
After a talk about the geology and examples of likely finds by Aidan Philpott, we headed north towards Hanover Point, looking amongst the shingle for ‘rolled’ dinosaur bone. Dinosaur bone is commonly found along this stretch of beach. However, it can be hard to spot amongst the abundance of similarly coloured lignite, but we were an eagle-eyed group and bone was soon being discovered. Dinosaur bone here is often described, as ‘rolled’, as it is most commonly found worn, weathered and rarely articulated – not only from being exposed to beach conditions, but also from the intense storms and flooding it experienced before becoming fossilised. This often makes it hard to identify what bone it is or what animal it came from. However, Silas Shaul made a cracking find of a clearly defined dinosaur toe bone. As well as dinosaur bone, other notable finds included a Sheenstia fish scale found by Emma Philpott and the impression of a pine or cycadean cone found by Elliot Mills.
As the tide fell, the group explored the exposed soft ledges for fossils lodged in the rock pools. Nicky Parslow found some beautiful small in situ footprints on these ledges, which we were able to admire and photograph before they are lost to tidal action.
Later in the afternoon, the drizzle stopped and the sun began shining. As the tide had now retreated, it was a perfect opportunity to show the group a dinosaur trackway exposed far out on the shelf, as well as the impressive Pine Raft. The Pine Raft helps to illustrate just how intense the flooding that occurred here was. Preserved amongst the clay and mudstone are the remains of huge tree trunks, which would have been transported by a flooding event and lodged within the river system, where plant debris continued to build up. It is fascinating to see these huge trees in situ, which really helps us to visualise the area 127 million years ago. The dinosaur trackway also helps to visualise the animals that would have lived here. Exposed far out on the ledge, almost directly opposite Hanover Point, is a series of five footprints from a relatively small herbivorous dinosaur. The strides appear short, so we could imagine perhaps a juvenile Iguanodon casually strolling past. Sadly, along this trackway, one of the footprints is notably absent, because it was recklessly removed some years ago with a rock saw. This gaping square hole served to remind us about the importance of responsible collecting and why we must always observe the fossil code and SSSI restrictions, to preserve specimens for all to enjoy and discover.
We would like to extend our warmest gratitude to everyone who attended the Isle of Wight weekender. It was a pleasure to spend the time with such an enthusiastic and dedicated group of fossil hunters. We hope you all enjoyed, learned and discovered. And congratulations again to the Yan family for winning the coveted Golden Hammer on the UKAFH quiz.
Fossil Hunt at Ringstead Bay, Dorset Sunday 9th July 2017
Ringstead Bay remains an almost forgotten gem along the Dorset Coast. Despite the obvious beauty of the location, the site has never been commercialised. Private ownership of much of the land has prevented companies, such as Pontins or Butlins, from exploiting the area in the past and Ringstead Bay remains much unaltered. The winding lane leading down to the bay is certainly not conducive to heavy traffic. Nowadays, the area is under the care and ownership of the National Trust and despite a fairly busy scene around the beach café and car park on Sunday, the rest of the large bay was characteristically mostly deserted, even on a blisteringly hot summer day, as we found out! A few hundred yards away from the slipway and the peace and tranquillity of Ringstead Bay becomes apparent. A brief talk, by Steve, set a backdrop to the location; the geology, the fossils and the Jurassic coast.
To the west of the bay, the harder rocks of the Corallian sequence form the headland of Bran Point, composed mostly of the Osmington Oolite Series and packed full of the large cockle Myophorella clavellata, which are also evident in the reefs and rock pools at low tide. To the east, the majestic Chalk cliffs of White Nothe form a prominent cliff. In between, the tall, slumped and badly weathered cliffs within the bay are entirely composed of Kimmeridge Clay, which is where our hunt began.
The Kimmeridge Clay here is 151 to 156 million years old and is composed of much degraded mudstone, formed on the Jurassic sea bottom when England once bathed in a sub-tropical climate. In fact, it was probably much the same as the day of our hunt, where the sun shone fiercely and the sky and sea were blue and mostly cloudless.
After an introductory chat, explaining the geology of this part of the Jurassic Coast, the party descended to beach level and the hunt was on. Ringstead Bay suffers much the same as other locations at the height of summer; poor erosion from tides and rain and from tourists. The tourists love fossil hunting in Dorset and consequently the more usual specimens found at Ringstead Bay were in short supply. Local collectors wait for the autumn and winter storms to help stir up the coast replenish supplies of fossils. However, the recent lack of good storms, even over the winter, has also meant fewer cliff falls and fresh material being exposed. The Kimmeridge Clay here was very dry and finding fossils within the hard clay body was not easy. However, the first fossil – a piece of the oyster, Deltoideum delta- was found by 6-year old Sophie de Candole. This was followed by several large complete oysters of the same being picked up by most members of the group.
Pieces of hard shale, which could be easily split by hand, exposed several ammonites and various shells. The largest ammonite remained in an immovable boulder on the beach but Aaron Roberts, aged 11, found a nice smaller specimen. The Sandsfoot Formation, which marks the junction between the older Corallian rocks with the overlying, younger Kimmeridge Clay was exposed in the cliff and formerly known as the Ringstead Coral Bed. Broken ‘chunks’ on the beach revealed little in the way of fossils, although 12-year old Cem Izzet found a good-sized bivalve, named Ctenostreon proboscideum. whose large strongly-ribbed shell is unmistakable and easily recognised.
Halfway along the bay, high in the cliffs, are the visible strata of the Portland Limestone Formation and capped by the basal part of the Cretaceous Purbeck Formation. The folded and faulted rocks, form a spectacular unconformity, with the Chalk dipping to the right and the Portland and Purbeck rocks dipping towards the right.
The day was certainly a success. The majority of the group found various fossils and were very pleased with the outcomes. Coupled with the glorious weather, it was a wonderful day out and encouraged those who had never been to the location before, to return. Many thanks to everyone who came along and UKAFH look forward to seeing you on another hunt.
Steve Snowball
Fossil Hunt at Monmouth, Dorset 25th June 2017
On Sunday the 25th June, UKAFH attended a hunt at the ‘Mecca of palaeontology’; namely Lyme Regis in Dorset. Lyme Regis is where fossil collecting and palaeontology all began and where, in 1811, Joseph Anning, the older brother of Mary, dug up a skull of an ichthyosaur on the ledges on the beach. At the time, he thought it was a crocodile but the significant find was followed by Mary’s own discovery of the skeleton that accompanied the 4-foot long head and the rest is history, as they say! Mary Anning went on to become the world’s most famous fossil collector and the discoverer of ichthyosaurs, plesiosaurs, pterosaurs, fish and countless other fossils from this very location. She undoubtedly paved the way for this newly evolving science at the time.
Although nobody in the UKAFH party found anything as spectacular, the coastline at Lyme Regis certainly sets the scene for any fossil enthusiast. The constantly crumbling cliffs can reveal ammonites and other fossils on an almost daily basis. This, of course, has its drawbacks also because during the summer months, hundreds of thousands of people flock to the Jurassic Coast, especially to Lyme Regis and the neighbouring Charmouth, to chance their arm at finding a fossil. Consequently, with low erosion rates, particularly during the summer and with every man and his dog combing the beaches, it’s never an ideal time. Undaunted however, our party made the most of dry weather and great scenery.
As is usual, we began with a short explanation about the geology and what could be found there. To the west of the Cobb at Lyme Regis is Monmouth Beach and here the famous rocks of the Blue Lias Formation can be seen, extending west to Pinhay Bay. The distinctive cliffs of layered limestone and shale is present, particularly at Ware Cliffs. The rocks are the oldest in the sequence of rocks found along the Jurassic Coast and date from around 199 million years ago. These hard, pale layers of limestone and darker organic-rich shales, also occupy much of the foreshore around Lyme Regis, appearing as a series of ledges on the foreshore at low-tide. The rocks gently dip towards the east and the overlying Shales-with-Beef Member and the Black Ven Marl Member (both from the Charmouth Mudstone Formation) eventually reach beach level, beneath Black Ven and East Beach at Charmouth.
Looking for fossils in the cliffs at this location is both dangerous and pointless. The rocks are under constant attack by the sea and the fossils are washed out of the clays and shales and deposited on the foreshore, between the rocks and boulders on the beach and ledges. Searching in these places is far more productive and members of the party were encouraged to do just that and soon some finds were found. As explained, there is a low frequency of fossils during the peak season and specimens that were picked up were in no way spectacular but they, nonetheless, were representative of the myriad of life forms which were present in Jurassic seas; for this is where Lyme Regis was once located. Then, the current Dorset coast was enjoying a climate similar to the current coast of North Africa and the nearest land mass lie many miles away. Consequently, fossils are mostly of marine origin, despite them being from the time of the dinosaurs. Dinosaur remains and vegetation are rare as fossils at Lyme Regis and such fossils are invariably of those organisms that were swept into the sea, from the nearest land, only to sink into the muds and silts of the ocean floor. However, bones and teeth of marine reptiles, such as ichthyosaurs, plesiosaurs and pliosaurs are common finds but not during our hunt, alas!
As with most hunts at coastal locations, the best time is to coincide with a falling tide, which is exactly what we did. The walk along Monmouth Beach, traversing rocks and boulders, searching for fossils can be quite arduous and we soon reached the spectacular ‘ammonite pavement, very near to our destination at Pinhay Bay, just as the tide retreated fully. This incredible stretch of foreshore accommodates dozens, perhaps even hundreds of large ammonites among the boulders and in situ on the exposed bedrock. These particular ammonites cannot be collected but their enormous size and abundance makes them worth seeing all the same.
On the way, members of the party found a number of ammonite fragments and in the case of Rebecca Walsh, a complete ammonite. UKAFH Leader Lizzie Hingley found a nodule, which looked quite promising until it was expertly cracked open, to reveal a highly an ammonite badly preserved in calcite within! However, she did find a nicely preserved Gryphaea (an oyster) and a large bivalve from the slumped Upper Greensand boulders found nearer to Pinhay Bay. Serpulids (worms), belemnite fragments, gastropods and various bivalves were also found by the party, so despite the finds being unspectacular and few everyone thoroughly enjoyed a sunny (yes, the sun finally came out!) and informative day, on the stunning Jurassic Coast of Dorset. Many thanks to all who attended and made this a very enjoyable event.
Please note that the site is given SSSI status, as part of the Jurassic Coast World Heritage Site, so the cliffs themselves are not to be hammered into.
Steve Snowball
