ammonites

UKAFH visit to King’s Dyke Nature Reserve, Sunday 19th August

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20180819_131316On 19th August UKAFH visited King’s Dyke Nature Reserve at Whittlesey near Peterborough.  This highly productive, family-friendly location is always a popular hunt and places quickly filled up so we had a full house of 35 with leaders Aidan Philpott and Sam Caethoven.

The geology of the location consists the Peterborough Member of the Oxford Clay Formation, representing the middle Jurassic period of circa 180 million years ago.  The clay is quarried for brick making but a spoil heap is provided in a designated area for fossil hunting and it was to this area we were destined today.

We were fortunate to enjoy warm but overcast weather, making hunting comfortable and dry. We kitted up we headed down to the dedicated fossil-hunting area where Aidan gave the group an introduction to the fossils that can be found.  The commonest finds are ammonites (especially Kosmoceras), belemnites (especially Hibolithes) and gryphaea, an oyster often called “Devil’s toenail” because of their curled, scaly appearance. However marine reptiles have also been commonly found in the quarry as well as teeth and bones from fish including the ray-finned Leedsichthys, probably the largest fish ever to have lived. An abundance of bivalves and brachiopods can also be found.

The location has an enormous quantity of fossils available and they are very easy to find, making it equally perfect for beginners who want to take home a treasure or two and for old hands who want to find something special, be it a bone, fish remains or a particularly large, complete or well-preserved specimen. The clay is easy to dig into and split so it is never a question of finding fossils; rather of narrowing down the large volume of finds into “keepers”. Soon we had good finds turning up, including calcite Kosmoceras ammonites, plenty of belemnite sections and an abundance of gryphaea.

Although on this occasion no-one was fortunate enough to find any reptile bone,  a Hybodus sp. shark tooth was found by Silas Shaul – the first I’ve personally encountered from this site. Well done Silas! Some sharp-eyed hunters like Billy Currie found small fish scales, bones and vertebrae and Tracey Herod found a beautifully preserved calcite-filled gastropod with its aragonite shell still in place.

As events drew to a close we received many kind remarks from attendees who commented on how they had enjoyed their day and were pleased with their finds.  We always love to hear your comments and see pictures of your finds, whether from one of our hunts or your own forays so please do share your news on our website and facebook pages!  Also please do sign up to our mailing list or keep an eye out on our website for forthcoming 2019 hunts which will be published soon.

Sam Caethoven

Fossil Hunt at Lyme Regis February 3rd 2018

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It was grey, cold and with weather forecasts that Captain Scott would have shuddered at the thought of! Undeterred, our group met in the Charmouth Road car park and descended to the beach, via the new sea wall next to Church Cliffs, with unsurpassed views of Lyme Bay and to Seatown and Golden Cap in the east. After a welcome to the delights of the Jurassic Coast location and an introductory talk, which took in the geology, Mary Anning, coprolites, public toilets, cliff falls, David Attenborough’s ‘Sea Dragon’, an introductions to UKAFH staff and our ‘guest helper’, Brandon Lennon, we all headed east.

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The geology here at Lyme Regis is quite complex. The cliffs and foreshore between Lyme Regis and Charmouth represent three stages within the Early Jurassic (or Lias) period termed the Hettangian, Sinemurian and Pliensbachian, dating from approximately 199-189 million years ago.

Essentially the rocks at Church Cliffs are Jurassic-aged from the Sinemurian stage. The Hettangian stage rocks of the older Blue Lias slowly dips away eastwards beneath sea level and the Shales-with-Beef layer, capped by the Black Ven Marls (part of the Black Ven Mudstone Member) and in turn, part of thr Charmouth Mudstone Formation descend to the beach under Black Ven. The younger Pliensbachian rocks are best studied at Charmouth. During this time a shallow epicontinental sea (less than 100m deep), was present across much of Europe, including most of England, Wales and Ireland, and laid down alternating layers of clay and limestone. At that time, Lyme Regis (as it’s now known), lay closer to the equator, roughly at the latitude North Africa is today.

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Armed with all the background, our intrepid explorers heading off. The best place to look for fossils is among the pebbles and rock pools on the foreshore, loose fossils including ammonites, belemnites and reptile bones can all be found with a little patience. Fossils can also be found protruding through the surface of the slumping clays along the top of the beach. At high tide the waves wash away the soft clay, leaving the more resistant fossils exposed and able to be collected by hand.

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Our hunt took place on an exceptionally low tide and Lyme’s famous ledges soon began to appear. This is usually a great place to look, as fossils are washed out of Black Ven’s clays and are deposited in the rocks and boulders and in fissures on the ledges. But finds were remarkably thin on the ground and despite some of our party finding a few very small ammonites, along with fragments from larger specimens, not much else turned up. Andrew Baylis found an ichthyosaur vertebra, which is a common find at Lyme Regis. However, the rain, sleet and snow forecast did not materialise! How wrong can the forecasters get it?

As the tide extended further out into the bay, boulders with large ammonite impressions appeared, not dissimilar to those found on the ‘Ammonite Pavement’ on Monmouth Beach.

Finding fossils is never guaranteed and participants of this hunt were not disappointed with the few specimens that were found. The coastal scenery was dramatic and the forecast inclement weather held off! Many thanks o all who attended, many of whom went on to the Charmouth Heritage Centre, to see the newly displayed ichthyosaur skeleton, discovered recently at Lyme Regis and made famous by David Attenborough’s ‘Sea Dragon’ BBC documentary.

 

 

UKAFH weekender at Folkestone and Samphire Hoe, Kent 14th and 15th October 2017

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The Folkestone foreshore

On Saturday 14th October UKAFH took a group out to the Warren, Folkestone for day one of the Kent weekender.  We were blessed with unseasonably warm weather as our group of 30 descended the (pleasantly dry) mud footpath down to the beach to begin our hunt through the Cretaceous period! Once on the beach, UKAFH leader Chris Tait briefed the group on the geology of the location and what we might expect to find.

The rocks at Folkestone represent the Albian stage of the lower Cretaceous, 110-105 mya.  Lower Greensand is found at the base of the cliff with Lower and Upper Gault clay resting conformably atop, however the clay slumps over the Lower Greensand and is eroded at sea level to release large volumes of fossils onto the beach in this highly productive locality for fossil hunting.  During the time these sediments were laid down the UK was at a more southerly latitude in the area of the modern day Mediterranean and a warm sea teeming with life covered the UK.  During this time sea levels were transgressing, with the Lower Greensand being deposited as and continued to erode, to be replaced with fine clay sediments once nearby land was completely submerged.

The Lower Greensand is less fossiliferous as the near-shore environment it represents was less suitable as a habitat but still contains excellent fossils such as ammonites; the Gault Clay, however, is packed with diverse fossils, some with exceptional preservation. Ammonites, belemnites and molluscs are common; nautilus, crabs, crinoids, fish remains, shark teeth and scaphopods can be found, along with rare finds of reptilia. Examples of all of these were found by members of our hunt group!

Phosphatised preservation is typical but quality is variable, with examples often fragmented or in nodules.  However many examples are preserved in superb detail in pyrite and those which are newly emerged from the clay can retain some or all of their nacrous shell.  Bivalves and molluscs which are newly exposed are often extremely fragile and are rarely collectable unless carefully removed along with the surrounding clay, but ammonites are more durable and make marvellous specimens to add to a collection.

Soon after we reached the beach heading towards Copt Point the finds were already plentiful.  Partial regular and heteromorph (partially uncoiled) ammonites and bivalves were quite common and finds increased as people “got their eye in”. Some of the group progressed quite quickly along the beach to inspect the slips of clay for freshly washed out fossils and check out the shingle between the large rocks and boulders on the foreshore. Others remained nearer the start of the beach, working methodically through the shingle by hand, with a trowel, or dry sieving, in search of smaller finds like shark teeth.

Several members of the group found shark teeth, with Isabelle finding the largest example.  At the other end of the scale, Sam found a small but scarce Acrodus shark tooth while sieving using a 3mm mesh. Sieving is a good technique to remove sand and search for small fossils which wash out higher up the beach because they are lighter. Sieving and shingle-searching up the beach yielded crabs, solitary corals, urchin spines, shark teeth and vertebrae as well as fish teeth, a turtle bone and the day’s star find, a swordfish tooth!

By the end of the day we had a really great selection of finds amongst the group!

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Leader Selfie

The following day we were greeted with yet another gloriously sunny autumn day, enhanced by the towering white cliffs of Dover above our meeting point as Samphire Hoe Country Park.  We had another full house of attendees and headed west along the beach to hunt for fossils amongst the chalk boulders on the foreshore.  Aidan Philpott, UKAFH Leader, explained the geology and identified local fossils to look for to the group. The lower chalk (also known as the grey chalk) at Samphire Hoe is from the Cenomanian stage of the Upper Cretaceous so yields fossils aged 100.5 – 93.9 Mya.

Common finds are brachiopods, bivalves and echinoids. Sponges, shark teeth, worm tubes, gastropods and fish can also be found and, rarely, ammonites. As well as beautifully preserved fossils within the chalk, some echinoids and shells and many sponges form flint casts which can be washed out of the chalk and found in the shingle.  Attractive pyrite crystals can also be found in the chalk.

Our first find of the lay was an eroded echinoid inside a flint block.  UKAFH leader Chris Tait then found a large section of clam.  These giant molluscs are mostly found broken into small pieces so this was a really nice find.  As the day progressed a good variety of finds were made including echinoids, shark teeth and brachipods.

Samphire Hoe isn’t the easiest location for fossil hunting as you need to scrutinise the loose chalk boulders on the foreshore carefully for signs of fossils and then extract them very carefully with a chisel to ensure they are not damaged.  You can also hammer the boulders to break the chalk up in search of fossils so work, tools and care are needed to have a good chance of finding fossils here.  Once extracted, however, preservation is usually excellent, with fine details clearly visible.

Cleaning chalk fossils is easy, requiring little more than dry brushing the remaining chalk matrix with a soft brush (a children’s toothbrush is ideal) to remove any chalk remaining on the fossil surface.  As chalk is very soft, you can easily remove larger amounts of remaining chalk with a blunt knife or craft knife until you approach the surface of the fossil and switch to brushing.

Finds were pleasing but not abundant, however everyone enjoyed the hunt and the sunshine day.

Chris, Aidan and Sam, your UKAFH leaders, would like to thank all of our members and attendees for joining us on our weekend fossil extravaganza and we look forward to seeing you all soon!

Click here for our UKAFH news and to see out upcoming events (we update the list regularly so check back often!)

FOSSIL HUNTING EVENTS

 

 

Photos from UKAFH’s fossil hunt at King’s Dyke Nature Reserve, Sunday 13th August

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King’s Dyke quarry
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Small reptile tooth – crocodile?
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Iridescent Kosmoceras ammonite
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Coprolite
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Beautiful ammonite
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Incredible fish skull and fins
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More ammonites!
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Ammonite with nice 3D preservation
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Fossil wood
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Incredibly preserved plesiosaur vertebra
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Ammonite
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Beatifully preserved bivalve
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Leaders Chris Tait, Aidan Philpott and Sam Caethoven