A Carboniferous Fossil Forest in North Wales: Problems and Potentials Associated with Developing and Conserving a ‘Soft-Rock’ Site
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A small area of Duckmantian deposits at Brymbo, Wrexham, in North Wales contains a variety of sedimentary rocks laid down between two coal seams. The exceptionally well-preserved flora contains three dimensionally preserved Calamites, Stigmarias and lycophyte stems in their original positions of growth together with a varied flora of compression plant fossils. The site is protected as an SSSI and has been included in the Geological Conservation Review, and the ownership will be transferred together with adjacent scheduled buildings from the former iron and steel industry to a Heritage Trust. Its future seems secure but such soft-rock sites deteriorate through exposure to the weather. The plan to develop it as an educational and research site relies on its survival, and the only secure way is to enclose the site, which will then permit further excavation and exposure of the plant fossils.
KeywordsCarboniferous North Wales Fossil Forest Sedimentary rocks Geoconservation
Geoconservation does not have the same priority in the general public’s mind as biological conservation. Interest in geology is stimulated by visiting different places to study the rocks, and teaching with the aid of notes on responsible fieldwork may temper any destructive tendencies to overcollect, but there is a need to instil in the aspiring geologist the need to save sites for future research or educational use.
Geological sites are being lost all the time through quarrying and landfill, but legislation within the devolved regions of the UK can bring about the purchase of sites for National Nature Reserves and more regional action can result in Local Reserves of geological interest. Most of our geoheritage is not preserved in this way, but a great many sites have been given protection as a Site of Special Scientific Interest (SSSI) and included in the Geological Conservation Review (GCR). In Northern Ireland, they are known as Areas of Special Scientific Interest (ASSIs) (Thomas and Cleal 2005, 2012). Nevertheless, even these sites can lose much of their value if they are left to degrade or become covered with vegetation. The type of rock in the designated sites can control any action necessary to ensure its continued usefulness. There is an enormous difference between hard rock igneous and metamorphic sites and those made up of sandstone and shale. Exposures of these ‘softer’ sites may be constantly renewed if they are on the coast, but problems arise if they are inland. Sometimes the only option is to cover them up again to preserve them (boon, 2004).
A new geological SSSI, which is also a new GCR site, in North Wales poses all the problems associated with these inland sites. Its study has revealed it to be an extremely valuable exposure for research and has the potential to be an excellent educational facility. However, the only satisfactory solution for the continued use of the site is to enclose it.
Coal has been mined in the area from at least the year 1410, and mines are recorded as being active in 1540 in ‘Harwd’ which is the old name for the village of Brymbo. However, Brymbo is best remembered not for its coal but for iron whose production commenced in 1796 with steelmaking beginning in 1885 and continuing until its closure in 1990. Many of the historic structures including the original eighteenth century blast furnace and foundry were retained in what is currently being developed as a ‘heritage area’.
The Scientific and Educational Value of the Exposure
Stigmaria is one of the iconic plant fossils of the Carboniferous, and fragments of the narrower parts of the rhizomorph are found in most museum collections. However, very few almost entire specimens have been found and preserved (Thomas & Seyfullah 2015b). The most famous are those of the Fossil Grove preserved in a small building in Victoria Park, Glasgow (McGregor and Walton 1972). Another group of Stigmaria was re-exposed at the new housing development at Middleton, Sheffield, but after charting them, they were covered over to preserve the remains from weathering (Boon 2004).
Careful recording of the plant fossils has enabled different assemblages to be recognised from the various strata enabling tentative ecological interpretations to be made. Representative specimens of all the taxa have been deposited in the National Museum of Wales, Cardiff, together with an illustrated data base.
The ability to see the changing sediments between two coal seams together with their differing assemblages of plant fossils, lycophyte stems and Calamites in their original growth positions and the potential to handle a variety of plant fossils and understand how they were formed make the exposure a rare and ideal educational facility for students of all levels from primary schools to university level.
Problems in Conserving the Site
The site is currently owned by Park Hill Development Company whose management has agreed that it will give the whole heritage area and the Fossil Forest to the established Brymbo Heritage Group. Its future therefore appears secure, but there are outstanding problems to be faced in saving the site for the future. The major threat faced in conserving the Fossil Forest is erosion and degradation through rain and frost, which is breaking up the exposed shale and destroying the plant fossils within it. The lycophyte stems and the Calamites exposed in side view are also weathering with those preserved in shale (Thomas 2014, Figs 10, 11) having been nearly all degraded and broken up. Many of the in situ Calamites preserved in sandstone have not yet been uncovered, being only visible as circular sections on the top of the sandstone (Thomas 2014, Fig. 14).
Part of the Fossil Forest has been temporarily covered by a membrane covering with drainage piping to take away the surface water, although the rest is still exposed. The upper 2-yard coal is exposed in a face at the end of the site where it is exposed to weathering and erosion. Theft has also been a problem, although most probably by local people taking fossils for their own interest. For both these reasons, excavation has been stopped for the time being. There are plans to fence the site which should prevent access to the exposure by unauthorised persons. Park Hill Estates have recently developed the adjacent restored large area of levelled land with roads and lighting for future housing, a school and retail outlets. This should not only bring a certain amount of security for the site but an added impetus to develop the Fossil Forest and the rest of the Heritage Area.
Long-term conservation for research and teaching will be only possible if the site is protected against continuing erosion by the weather, and this could only be achieved in an environmentally controlled building. The exposure could ultimately be viewed from raised walkways and information supplied through displays of fossils and instructive interpretation boards. Here, as always, the question of finance arises with current estimates somewhere in the region of £250,000 for a basic steel building and £1–2 million for its complete development as a scientific and educational facility.
I am indebted to Park Hill Estates and especially Mr. Andrew Foster for saving the site and permitting access to it for study. Special thanks are due to Mr. Peter Appleton who spent a great deal of time collecting and documenting the plant fossils.
- Boon G (2004) Buried treasure—Sheffield’s lost fossil forest laid to rest (again). Earth Heritage 22:8–9Google Scholar
- Calver MA, Smith EG (1974) The Westphalian of North Wales. In: Owen TR (ed) The Upper Palaeozoic and post-Palaeozoic rocks of Wales. University of Wales Press, Cardiff, pp. 169–183Google Scholar
- Cleal CJ, Thomas BA (1995) Palaeozoic palaeobotany of Great Britain. The Geological Conservation Review Series, 9. Chapman & Hall, London, p. 295ppGoogle Scholar
- Davies JR, Somerville ID, Waters CN, Jones NS (2011) Chapter 8. North Wales. In. A revised correlation of carboniferous rocks in the British Isles. Geological Society Special Report 26:49–56Google Scholar
- McGregor M, Walton J (1972) The story of the fossil grove at Glasgow Public Parks and Botanic Gardens, Glasgow, rev. edn. Parks Department, Glasgow, Glasgow D.CGoogle Scholar
- Thomas BA, Cleal CJ (2005) Geological conservation in the United Kingdom. Law, Science and Policy 2:269–284Google Scholar
- Thomas, B.A. and Cleal, C.J., 2012. Geoheritage in Europe: the U.K. In Wimbledon, W.A.P. and Smith-Meyer, S. (Editors) Geoheritage in Europe and its conservation. Progeo. 393–403Google Scholar
- Thomas BA, Seyfullah LJ (2015a) A new look at Lepidodendron ophiurus Brongniart and the recognition of L. wingfieldense sp. nov. (Flemingitaceae, Lepidodendrales) from the Langsettian (Bashkirian) of Derbyshire, East Midlands, UK. Palaeontographica B 92:23–32Google Scholar
- Webb, C.B., Smith, B., Wills, M.A. 1928. The Geology of the country around Wrexham, Part II Coal measures & Newer Formations Memoires of the Geological Survey of England and Wales: Explanation of Sheet 121, 237 ppGoogle Scholar
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