|Why is Shropshire important for geology?|
The advancement of knowledge and the widening of educational opportunities has encouraged the growth of geology as much as any other subject. The exceptionally diverse range of geological strata, in terms of both age and rock type, within Shropshire would be sufficient to place the County in the top set of localities, but added to this is its frontier position: at former plate boundaries, just below the major erosion surface of the crust prior to opening of the Atlantic Ocean, and the meeting point of several glaciers during the last Ice Age. Thus the variety of geological settings is unmatched within the British Isles or, within such a relatively small area, probably anywhere else in the world.
Click on the images for more detail.
Geology evolved as a discipline in its own right about two hundred years ago, as discussion focussed on the nature of science alongside an increasing enthusiasm for collecting and a desire for knowledge about the world around us.
Philosophical debates tended to take place in the capital cities, leading to establishment of scientific gatherings to facilitate discussion and record the deliberations. Thus were born the Royal Society (of London) and the Royal Society of Edinburgh, encouraging pioneering geologists such as James Hutton. They realised the need for facts to support their arguments, and thus took advantage of opportunities to travel. This was the period when fashion favoured the choice of brick rather than stone for buildings, yet many small local quarries were still accessible. Underground mining for coal and metal was increasing, and thereby opportunities for studying natural materials in situ.
Hutton chose to visit Shropshire about the time his 'Theory of the Earth' was published in the Transactions of the Royal Society (1788), meeting up with Charles Greville, a collector of minerals, through their mutual Salopian friend, Erasmus Darwin, grandfather of Charles Darwin (who was born in Shrewsbury). Together Hutton and Greville ascended the Wrekin, in later correspondence describing the rocks there as Primitive, i.e. as being ancient.
Robert Townson (portrait above) was another notable Shropshire resident and, like Hutton, a Fellow of the Royal Society of Edinburgh. He travelled extensively, increasing his knowledge of mineralogy to the extent that in 1798 he was able to publish his 'Philosophy of Mineralogy' and, in the following year, 'A sketch of the Mineralogy of Shropshire' within his 'Tracts and Observations in Natural History and Physiology': the first substantive account of the geology of Shropshire (a copy resides in the County Archives).
This was a period of rapid expansion of industry and the accompanying need for raw materials. The location and assessment of these resources were the provenance of the mineral surveyor, precursor of the field geologist. Survey work accompanied systematic mapping of the land, a massive undertaking placed in the hands of the Royal Engineers, this branch later to become separated as the Ordnance Survey. Thus the Wright brothers (Robison and Romley) came to work in Shropshire and not only compiled the first accurate topographic map of the County but also recorded on a copy their geological observations together with a cross section to show what they thought might lie beneath the surface.
Murchison and the Silurian
Roderick Murchison saw the Wright brothers' map before embarking on his historic tour of England and Wales in 1831; this was perhaps the principal reason he came to Shropshire. This was most opportune, since on the way he visited the Wye Valley and recognised there a correspondence in the sedimentary strata, hitherto thought to be too diverse and distorted to be elucidated (then known as the 'Grauwacke', of the 'Transition Era', transitional between the ordered strata of the Coal Measures above and the Primitive, i.e. igneous and metamorphic, rocks beneath). Relating his observations to his hosts in Radnor prior to arriving in Shropshire, the enthusiasm and observations of the local natural historians present not only spread to Murchison but led him to realise the importance of integrating local knowledge with his own, broader based, concepts of the Earth's structure.
Thus Murchison sought to meet local amateur geologists on arriving in South Shropshire, among them Dr Thomas Lloyd, the Ludlow doctor, and Thomas Lewis, the curate at Aymestrey. Their collections of fossil fish from the supposedly unfossiliferous Old Red Sandstone (Lloyd) and systematically collated fossil shells annotated with the strata that hosted them (Lewis) enabled Murchison to deduce an order for his Silurian System, thereby defining one of the most important time periods within the Lower Palaeozoic, a period which saw the evolution of life migrating from the sea into fresh water and onto land for the very first time.
Ludlow Bone Bed
Details were to be refined in the years to come, and are still undergoing refinement as new discoveries are made (for instance recognition of early plant life by Dianne Edwards at Cardiff University and discovery of fantastically well preserved fossils in the Silurian Seas by the Siveter brothers). Murchison decided to define the top of the (marine) Silurian and its passage into the estuarine and river environments of the Old Red Sandstone (later to become known as the Devonian) at the 'lag' deposit called the Ludlow Bone Bed. Originally thought to be a layer of sediment packed with the remains of the earliest fish bones, recent work shows that this remarkable deposit actually contains charcoal fragments too, the remains of fossil plants burnt in the earliest wildfire known to have taken place on Earth, and then washed downstream with the flood from a violent thunderstorm.
Just over one hundred years ago, studies of the evolution of life were being pioneered by researchers from Mason College, later to become the University of Birmingham, under the direction of Charles Lapworth. Notable were the Salopian studies by three women (at a time when it was socially almost unheard of for females to undertake field work): Gertrude Elles, Ida Slater and Ethel Wood. These women were to publish important evidence for the evolution of graptolites, fossils of algal-like creatures which were not only widespread in the Lower Palaeozoic seas but evolved relatively quickly, and thus extremely useful for correlation of strata across the world.
Studying the surface morphology of Shropshire had been the interest of Arthur Aikin at the end of the 18th Century (e.g. his 1797 'Journal of a tour through North Wales and part of Shropshire; with observations in mineralogy and other branches of natural history'); Aikin was to go on to become one of the founding members of the Geological Society of London, the world's first such body, in 1807. 150 years later Leonard Wills took the subject further with his study of the river terraces of the Severn, and in the 1960s Peter Cross extended this to the Teme and was able to show that this river had, along part of its course, actually reversed its flow, the result of glacial interference with the drainage system.
Quite why central Wales and the Marches had its higher land levelling off to an apparently uniform plateau was, until recently, very much a mystery, but the work of John Cope over the last decade has shown that this may well be due to this part of the country passing over a hot spot in the Earth's interior, causing the land to rise and subsequently sink as the Atlantic began to open. This was a consequence of the crust losing some of its strength as it was heated above the hot spot, followed by partial melting, movement and recrystallisation of material from the base of the crust causing it to thin in the centre and thicken towards the margins. Such changes in crustal thickness caused an eventual drop in elevation at the centre (the Irish Sea Basin) and uplift around the margins (including mid Wales and the Marches).
Plate tectonics and a 12,000 km journey
Sudden breaks in the pattern of rock outcrops could be the result of cracks within the Earth's crust. Evidence is seen in the discontinuity of the rock sequences throughout the County, by the occurrence of occasional (small) earthquakes, the presence of anomalously high temperatures of groundwater, and the presence of radon gas. These are all features associated with faults that may still occasionally move and so provide zones of weakness allowing fluids to migrate through the crust. The development of faults is related to stress. This can arise as a result of loading and unloading as rocks become deposited and subsequently eroded, and by the development of glacial ice sheets. Of equal importance is the stress developed by plate movements, as indicated by the work of Nigel Woodcock and colleagues from Cambridge University. Indeed, Shropshire has had a remarkable passage of some 12,000 km in just 500 million years due to this process, migrating from south of the Tropic of Capricorn to its present day location, and is still moving northwards.
Ludlow Research Group
The need for precise dating of the rock sequence and its correlation with other parts of the world led first to detailed studies of their distribution in this area, notably in the mid 20th Century by members of the Ludlow Research Group (LRG), initiated by Stephen Straw and developed by his research team (Charles Holland, Jim Lawson and John 'Mac' Whitaker and, later, Vic Walmsley). The international dimension was developed further in the 1970s and 80s by Robin Cocks and Mike Bassett, leading to a visit by the IUGS Subcommission on Silurian Stratigraphy in 1979, and again in 2011 (click here for further details). The LRG continues to encourage geological research on the Silurian through its network of contacts fostered by annual meetings in the field.
The collecting of curios from the natural world was most popular during Victorian times. The Ludlow Natural History Society, founded in 1833, soon considered establishing a museum, and thus was born the Ludlow Museum and Resource Centre which continues to this day. The early collection included the fossils that were of such importance to Murchison in his definition of the Silurian. Such collections have international importance and thus the collection was passed to the Natural History Museum in South Kensington a hundred years later, for more detailed scientific study and professional curation and conservation, facilities not then available to a small local museum. However, the arrival of John Norton in the 1960s saw the collection regenerated and a new phase of activity focused on public information and education, a role now replicated across the country in recognition of the need for knowledge and conservation of the natural heritage, and for underpinning tourism, which is now one of the most important contributors to the economy in many rural areas. Details of the collections are in the process of being transferred to the Discovering Shropshire web site.
The County has several other museums and exhibition venues which portray the local geology, including:
Shrewsbury & Atcham
until recently located in Rowley's House (Shrewsbury) but currently undergoing transfer to the old Music Hall; much of its material is accessible online at:
which houses an important collection of flint implements collected close by, evidence of early trading through this region between central Wales and southern England.
Ironbridge Gorge Museums
include the Jackfield Tile Museum, which has 4000 geological specimens collected by George Maw in the nineteenth century.
There is a trail guide for those wishing to learn more about the geology of the Gorge (click here to see the PDF).
Much Wenlock Museum
Shropshire Hills Discovery Centre (Craven Arms)
including the GEOcaching Secret Hills Time Trail in Onny Meadows, adjacent to the Visitors' Centre.
Elsewhere in the region there are several museums which house important collections of Shropshire geology, including:
Herefordshire Heritage Services Resource Centre
Lapworth Museum at the University of Birmingham.
Education, Conservation, Publication
Visits to the County by school groups, university field trips, amateur geologists and holiday makers are numerous. To support this high level of interest there have been many publications, original studies published in the scientific literature (especially the Quarterly Journal of the Geological Society, the Proceedings of the Geologists' Association, the Geological Magazine and the Geological Journal), in the journals of local natural history societies (notably the Transactions of the Woolhope Naturalists' Field Club and our own Proceedings of the Shropshire Geological Society), and in books providing an overview, ranging from Townson's 1799 'A sketch of the Mineralogy of Shropshire', through Murchison's 1839 'Silurian System' and Wills' 1948 'Palaeography of the Midlands', to Peter Toghill's 2006 'Geology of Shropshire', now in its second edition.
The British Geological Survey under David Schofield's direction is currently planning to resurvey the Marches and thereby bring up-to-date the early studies by the Wright brothers, Murchison and the LRG. Scope for new geological studies in the County is considerable, as is the need for geoconservation and education, aspects summarised in the Geodiversity Action Plan published in 2007, available online.
Click here to see the Geodiversity Action Plan for Shropshire.
Click on the map below to see the detail
published in Stanford's Geological Atlas (Woodward, 1914).
This gives some idea of why Shropshire has been, and continues to be, important for geology and those interested in the landscape and the ground beneath our feet.
Suggested reading on this topic:
Anon. (2007). Shropshire Geodiversity Action Plan. Shropshire County Council. Available on-line at: http://www.shropshire.gov.uk/planning.nsf/open/EEE885581E0DAEF280257516003D64B6
Cope, J.C.W. (1994). A latest Cretaceous hotspot and the southeasterly tilt of Britain. Journal of the Geological Society of London, 151, 905-908. Fellows click here to see the PDF
Cross, P. & Hodgson, J.M. (1975). New evidence for the glacial diversion of the River Teme near Ludlow, Salop. Proceedings of the Geologists' Association, 86, 313-331.
Glasspool, I.J., Edwards, D. & Axe, L. (2004). Charcoal in the Silurian as evidence for the earliest wildfire (Ludford Lane). Geology, 32(5), 381-383.
Holland, C.H. & Bassett, M.G. (1989). A global standard for the Silurian System. National Museum of Wales, Geological Series No. 9, Cardiff, 325 pp.
Holland, C.H. & Lawson, J.D. (1963). Facies patterns in the Ludlovian of Wales and the Welsh Borderland. Liverpool and Manchester Geological Journal, 3(2), 269-288.
Lloyd, D. (1983). History of Ludlow Museum 1833-1983. Ludlow Historical Research Group, 23 pp.
Murchison, R.I. (1839). The Silurian System founded on geological researches in the counties of Salop, Hereford, Radnor, Montgomery, Caermarthen, Brecon, Pembroke, Monmouth, Gloucester, Worcester, and Stafford: with descriptions of the coal-fields and overlying formations. John Murray, Albermarle Street, London, 768 pp (2 vols plus geological map). Also on-line, in the Oxford Digital Library: http://www2.odl.ox.ac.uk/gsdl/cgi-bin/library?e=d-000-00---0munahi10--00-0-0-0prompt-10---4------0-1l--1-en-50---20-about---00001-001-1-1isoZz-8859Zz-1-0&a=d&c=munahi10&cl=CL1.6&d=munahi010-abu
Rosenbaum, M.S. (2008). The ground beneath our feet: 200 years of geology in the Marches. Proceedings of the Shropshire Geological Society, 13, 1-4. Click here to see the PDF
Schofield, D.I. (2008). The future for geology in the Marches: a BGS perspective. Proceedings of the Shropshire Geological Society, 13, 164-170. Click here to see the PDF
Siveter, D.J. (2008). The Silurian Herefordshire Konservat-Lagerstatte: a unique window on the evolution of life. Proceedings of the Shropshire Geological Society, 13, 60-63. Click here to see the PDF
Toghill, P. (2006). Geology of Shropshire. 2nd Edition, The Crowood Press, Marlborough, 256 pp.
Wills, L.J. (1937). The Pleistocene history of the West Midlands. Presidential Address to Section C of the British Association for the Advancement of Science, Report of the Annual Meeting, 1-8 Sep, 71-94.
Woodcock, N.H. (1984). Early Palaeozoic sedimentation and tectonics in Wales. Proceedings of the Geologists' Association, 95(4), 323-335.
Woodward, H.B. (ed.) (1914). Stanford's Geological Atlas of Great Britain and Ireland, with plates of characteristic fossils preceded by descriptions of the geological structure of Great Britain and Ireland and their counties; of the Channel Islands; and of the features observable along the principal lines of railway. 3rd edition, Edward Stanford, 12-14 Long Acre, London, xii p., 1 fold. l., 214 p., 50 (i.e. 53) double pl. incl. 42 col. maps, front., illus. 20 cm. Also on-line: http://www.maproom.org/00/35/index.php
Please also take a look at our Resources page, which gives access more detailed information regarding libraries and literature pertinent to Shropshire's geology.
Contacting the Shropshire Geological Society:
Click here to see full list of Shropshire Geol Soc Committee Members and Officers
We would like to thank Chris Darmon of Geo Supplies Ltd for his suggestion that we give an indication of Shropshire's place in the history of geology.