shark teeth

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

Posted on

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

field trip to Ramsholt – 10th June 2018

Posted on Updated on

On Sunday June 10th UKAFH visited Ramsholt, located on the river Deben in Suffolk. We met near the Ramsholt Arms, a popular pub with tourists and boaters, then walked about 2 miles north through woodland and along the river bank before reaching a shingle beach where fossils are abundant.

UKAFH leader Sam Caethoven explained the geology and pre-history of the site and provided an example of likely finds.

IMG_0498

There are three distinct deposits exposed at Ramsholt. The base of the small exposed cliffs and the foreshore consist of London Clay, a roughly 50 million year old marine deposit commonly exposed on the south east coast from which many bivalves, gastropods, crabs, lobsters, shark and ray teeth, fish, reptile and mammal remains can be found. Above the London Clay sits the Coralline Crag formation, a much younger (~ 5 million year old) sandy sediment containing numerous bivalve and gastropod remains. As the name suggests, the formation does contain corals however more common here are bryozoans, which can often be found with corals seeded within their chambers. The 5 million year old Coralline Crag comes to lay directly on top of the 50 million year old London clay as the underlying sediment was eroded before the Crag formed, this has resulted in a diversity of derived fossils in what is called the Basement Bed, directly above the Coralline Crag and forming the base of the roughly 2.5 million year old Red Crag above it. Derived fossils are those which, having become fossilised in one deposit have since been eroded out, often transported by rivers or tides, and become part of a much younger sediment. This means that, within the basement bed, fossils from the Eocene and Miocene can be found and even Cretaceous belemnites and crinoids have been found within the basement bed. The effects of “refossilisation” of shark teeth here are striking; the teeth are often polished and the colours derived from exposure to different elements are diverse and vivid. Marine mammal bone fragments, often attributed to whales, are also common from this bed and have become silicaceous in their preservation. The iron rich Red Crag above is also noted for well preserved and often complete bivalves and gastropods.

Finding fossils here is relatively easy as they can be found in abundance among the shingle of the foreshore – the site is SSSI protected and so digging in the cliffs or the exposed clay on the foreshore is prohibited. With fine, dry and warm weather it was not long before the group began making discoveries. Gastropods and bivalves from the Red Crag and Bryozoans from the Coralline Crag were the first fossils we noticed as we progressed north along the foreshore.

But it was not long before shark and ray teeth were being found, some fantastically preserved and some with vivid red, orange and even blue colours. Daniel Austin found a particularly rare and large Isurus tooth while Eliott Mills found an uncommon large Otodus tooth.

Other notable finds included some large pieces of marine mammal bone and a delightful although heavily worn crab carapace found by Aidan Philpott.