calamites
UKAFH visit to Seaham, Sunday 11th November 2018
On Sunday 11th November, UKAFH met on the coastline of Co. Durham, just outside Seaham, a small town about 6 miles south of Sunderland.
Unusually for a coastal hunt, we were focused on the spoil heap of the former Dawdon colliery that operated close by. Dawdon colliery began extracting coal in 1907, mining the Carboniferous coal seems far below the Permian bedrock the cliffs at this location are composed of. The spoil from the colliery consists of inferior coal, shales and mudstone which were dumped over the cliff edge, creating, in places, a second cliff of carboniferous material in front the Permian cliffs. Although once the most productive colliery in County Durham, employing over 3800 people, Dawdon colliery ceased extracting coal in 1991. Since then, most of the carboniferous sediment had been eroded away by the sea, but there is still ample opportunity to find spectacular fossils here.
The spoil consists of Carboniferous material about 320 million years old. At the time the sediment was created, County Durham was a vast and boggy forest. The upper canopy was densely foliated with the likes of Calamites trees – related to modern day horsetails, and Lepidodendron trees – related to modern day club mosses, although their modern-day ancestors are diminutive, these trees would have towered over 100ft above the forest floor. The forest floor, where abundant pteridosperms (seed ferns) such as Neuropteris thrived was hydrated and boggy, an ideal environment to preserve the foliage and timber which over millions of years built up to create the coal seems which were so highly prized here during industrial times. Also present in this forest of giant tree like plants were the giant insects the Carboniferous is also famous for – huge dragon flies would have traversed the dense canopy while monstrous millipedes up to 6ft in length would have scurried below. Although insect fossils are extremely rare, it is still something to keep an eye out for.
In complete contrast, the cliffs behind the carboniferous spoil is Permian in age, about 290 million years old and is formed of limestone from a shallow marine environment. Although Seaham is one of the best locations to find carboniferous plant fossils in the UK, the limestone originating from the cliffs should not be overlooked as these can contain bivalves, crinoids, corals and rare but possible fish remains.
After some examples of possible finds provided by Mike Greaves, we took a steep path from the national trust carpark at Nose Point down to the beach. We didn’t know it until we were on the beach that the path we followed and the apparent shelf we were now standing on was in fact the spoil from the former colliery. Here, Katherine Combe MSc provided a talk about the geology and where we were likely to find fossils. It wasn’t long before fossils were found, although the first fossils were that of crinoids originating from the Permian limestone of the cliffs. As we stepped off the spoil onto the beach the first plant fossils were found. Alice Brooks found a great Stigmaria fossil (part the of rhizomatous root of a Calamites tree) and Terry Newsome found some incredible fronds by carefully splitting shale.
Later we headed towards the foreshore where large sections of Lepidodendron trunks could be seen. Here, denser mudstones could be split with a hammer to reveal an abundance of well-preserved pteridosperm such as Neuropteris within. Jake and Matt Ellison found some delicately preserved Calamites leaves, Ben Simpson found some great Sigillaria and Ethan Wale found some beautifully preserved fronds. Mike Greaves found a stunning example of Calamites amongst the shingle.
We were grateful for the calm weather, apart from a few spots of drizzle, the temperature was mild, the wind was light, and we saw a glimpse of sunshine at times.
Being remembrance Sunday, we gathered and observed a two-minute silence at 11am. As an important supplier of coal to Britain during the Second World War, Dawdon Collier was bombed by the Luftwaffe in August 1940 which killed 12 and left 119 people homeless. This then, was a poignant place and time to remember those who have given their lives, not only in battle but also supporting the war effort back home, such as here, producing the supplies needed to win the war.
Thank you to everyone who joined us. A great group of people and some fantastic finds!
UKAFH visit to Betteshanger Country Park, Kent
On a scorching, sunny Sunday 5th August UKAFH members and guests headed to the south east corner of Kent to Betteshanger Country Park (near Deal) to hunt for Carboniferous plant fossils.
Betteshanger is a RIGS spoil heap at the old Betteshanger Colliery, which was the largest in Kent but was closed in 1989. Betteshanger Country Park was created by regeneration of the former Betteshanger colliery site and provides a large green parkland and recreation area ideal for walking, cycling and other outdoor activities. However as part of Geoconservation Kent (http://www.geoconservationkent.org.uk/), there is agreement to retain a fossil hunting area within the country park. The fossil collecting spoil heap, which is northeast of the original site, is set aside for the study of the fossils to be found in the coal measures formerly mined there and this was our destination for the day.
Our group of 25 assembled outside the visitor centre, which offers toilets, showers, information on the park and a small cafe alongside a childrens’ play area. From there it was quite a short walk to the fossil hunting area where Andy Temple of GeoConservation Kent awaited us as our special guest leader for the day. Andy regularly supports school and group trips and visits to Betteshanger and other Kent locations and is expert on the many, varied plant fossils to be found in the coal deposits. Sam Caethoven welcomed the group and introduced Andy who gave an overview on the site and what can be found.
Betteshanger is Upper Carboniferous (Silesian) in age, from the mid-Westphalian Stage (Asturian Substage of 323.2–315.2 Mya) to the Stephanian Stage (Stephanian B Substage of 315.2–307 Mya). The rocks are from between 316–311 Mya and mostly consist of the Kent 5 coal seam, with some Kent 7. Kent 5 is assigned to the Upper Coal Measures (Warwickshire Group) and Kent 7 to the (South Wales) Middle Coal Measures. Fossils show that there were areas of forest and river levees, with overbank deposition taking place.
Fossils at Betteshanger are found either lying on top of the spoil heap or by digging into the spoil. Remains of Arthropleura, a large arthropod, have been found at the site. However, unlike other coal measures sites in Europe, no insects have been found at Betteshanger.
When we arrived at the fossil area we were delighted to be informed by Andy that a digger had just been in to turn over the coal spoil and dig out fresh areas, removing the old spoil that had already been examined many times previously. As a result we were extremely fortunate to be able to find abundant, varied plant specimens!
Fossils were quickly being found, both in quantity and variety. Kath Kemsley found a smashing Neuropteris seed fern and Aiden Philpott found an exquisitely preserved Alethopteris seed fern. Jake Ashley found a very nice example of Lepidodendron (also known as a scale tree) which is an extinct lycopsid club moss. Kaitlin Asher found a fantastic selection of plant fossils and Nicky Parslow uncovered a beautifully detailed example of asterophyllites horsetail.
The swampy Carboniferous landscape was dominated by three types of plant: ferns (true ferns and seed ferns), lycopods and sphenopsids. Ferns were at their most abundant and diverse in the Carboniferous period but persist today. Giant lycopsids – clubmosses – such as Lepidodendron and Sigillaria grew to the height of trees and their fossilised bark is characterised by leaf scars. The fossils of the root systems of both these plants are called Stigmaria because they look so similar. These are examples of form taxa, where a collection of organisms is given a taxonomic name but is known to be a grouping based on similar morphological characteristics, rather than more extensive biological similarity. Finally the sphenopsids consist horsetails which were gigantic in the Palaeozoic but persist today in much smaller and less diverse forms. The leaves of horsetails, which form in whorls around the stem, are termed annularia but the root fossils are known as calamites.
Huge thanks to Andy Temple for bringing a fabulous display, expert advice, identification and preservation tips and plenty of very useful spare newspaper for wrapping finds!
