On a warm but comfortably overcast day a group of 20 UKAFH members met at the marina car park at Burnham on Crouch to study the geology and collect fossils from Butts cliff at Burnham on Crouch. Our leader for the day was Eliott Mills, who has lifelong experience of this and other London Clay locations. Eliott brought a number of superb specimens collected at Burnham on Crouch and other London Clay localities to illustrate the quality and diversity of fossil specimens to be found at this location. Fossils include over 20 species of shark tooth, crabs, lobsters, turtle, birds and fish as well as invertebrate fossils and derived fossils from the chalk such as sea urchins.
The London Clay (Eocene ~50 mya) from the Ypresian of the Eocene is well exposed at Burnham on Crouch. The beds dip westwards and there is a large amount of the sequence exposed. This is some of the oldest London Clay that is accessible.
The London Clay banks here still provide the collector with a rich assemblage of fish taxa, almost exclusively of elasmobranchs (cartilaginous fish, such as sharks, rays and skates). The tidal river cliffs and foreshore exposures reveal a section through the marine rich London Clay, Division D. The main cliff, known as ‘The Cliff’ or Butts Cliff locally, forms a 2 -3 metre thick outcrop on the north shore, which contains the fish fauna (mostly of sharks) which wash out onto the foreshore.
Large cementstone nodules from the London Clay are found here and resemble those found at Sheppey sites. However, at Burnham-on- Crouch, the concretions are largely unfossiliferous when broken open.
At the western end of Cliff Reach, the Upper Chalk is sometimes exposed on the foreshore in boulders. These can contain shells from the Maastrichtian stage of the Upper Cretaceous. This bed is directly beneath the London Clay.
After a walk if some 40 minutes the group arrived at the cliff and began searching for fossils. Many fossils are small and require careful searching through fine shingle but finds were quickly made.
Claire and Sam quickly found small shark teeth in the shingle and Jenny then found a cidarid sea urchin spine derived from the chalk. Xiang then found a bird bone, a rare and excellent find! Leon found a large and very well preserved striatolamia (sand tiger) shark tooth and Aidan found a complete ray tooth plate file.
As we continued to search the beach everyone was able to find and share examples of their finds. Many attendees were able to find small crab nodules and fragments amongst the shingle and Jack found a number of larger crab nodules at the margin where the shingle gave way to the clay which he kindly shared with group members. Steve found a fish jaw with clear tooth sockets and several fish vertebrae were also found.
The find of the day was made by Eliott, whose goal of many years was finally achieved when he found a Hexanchus (6 gilled cow shark) tooth. These tiny teeth are uncommon and many years of searching without success were finally paid for.
Finally the group began the long walk home as the tide came in. Always remember to be safe and to fossil hunt on a falling tide, along time to return safely taking account of any points along the route where there is risk of being cut off. Thank you to Eliott, Sam, Jack, Salma and Aidan, our UKAFH volunteer team for leading and supporting this event.