A CASE PUT FOR GEOLOGICAL STREET WALKS

  For a geologist, the streets of any town present a wonderful opportunity to practice their art. In cities, the offerings can be even more attractive for the many exotic stones which have been introduced as cladding to new buildings or as fascias to old shop fronts renovated. In walking, we are simply fastening on to the buildings of the streets as an open air Museum to Geology.

  Happily, Geology is an "observation" science, requiring only a keen eye and a receptive memory for the names which "authority" has offered for the stone seen in a particular building. It is a version if you like of Kim's Game, made easier for the beginner by our tradition in Britain of using our best available building stones and repeatedly going back to the quarries of Portland, Bath, and Hopton Wood for our limestones. To Darley Dale, Stancliffe or Low Fell for our sandstone (or the many quarries in Pennant Sandstone if we are in Wales). If it is granite, we have always looked to Dartmoor, Bodmin Moor, Aberdeen and Peterhead for these most decorative of stones.

  All of this covers the grander civic and commercial buildings of the 18th, 19th and early 20th centuries so we are always meeting time and time again rocks which become familiar through repetition. For sound geological conversations, the vocabulary needed is no great taxing of memory. Thanks to Empire and our once thriving export trade in stone, it can be a vocabulary which would serve in Cape Town, Sydney and New Delhi. Since the Second World War however, all has changed as the World has opened up to the stone trade with a consequence that modern buildings in the cities are likely to be faced with stone from Brazil, India, or South Africa as well as all parts of Europe seeking a sterling trade balance. A walk down any city street is thus a blend of native stone with a range of truly exotic granites and marbles never seen to previous generations of British geologists.

  Apart from the diversity of stone, street geology offers several useful advantages. First, there is the total areas of exposure. Square metres of polished stone compared with those small neat squares seen beneath the glass cases of the average museum. Wiped clean with a damp cloth, there is ample surface area from which to appreciate fossil content, crystal textures and sedimentary structures with the naked eye. In unpolished stone, if we know the date of a building, we can assess the extent and degree of weathering caused by pollution or "acid rain" which has reduced a once smooth stone surface to an etched and corroded roughness. A second advantage of street geology to us in our efforts to win the interest of the non-geologist public, is that we are making our contacts with them not in a lecture theatre where they have been coaxed to listen to a lecture on Geology, but somewhere where they feel much more comfortable—a familiar streetscape. For several years I have taken part in the successful programme of Open House, leading walks in Trafalgar Square. Last year, over 250 people joined me on four walks. Many of them knew the ground quite well, passing through the Square on their way to pass on information about the buildings for which I was describing the stonework. It was a two-way dialogue which I hope increased their daily journey and which might have made Geology less of an arcane science.

  The first significant published geological walk on city streets in my experience was "A Building Stone Guide to Central Manchester" published in 1975 by Ian Simpson and Fred Broadhurst for the Extra-Mural Studies Department of the University, which certainly became the model for my work in the following years. For the past 20 years, midday walks have been offered at the Annual Meetings of the British Association at whatever venue they have been convened. Walks were added to the BBC Website for Urban Studies in 1998 for Glasgow, Newcastle, Cardiff, Birmingham and London (St. Paul's, Trafalgar Square, Westminster, Greenwich, The Tower, with Windsor and Hampton Court in preparation). Now, almost all towns and cities have been covered as the application has dawned that this is our best contact with the non-geologist public.

  With geological street walks we have found common interest with civic societies, architectural historians, conservation areas in towns and individuals with civic pride. Of our more rewarding returns, however, we would have to list our new contacts with teachers seeking to fulfil the requirements of the National Curriculum in Science. "Crustal Materials" and "The Processes of Weathering" are easier to demonstrate on the streets close to the school than in the confines of the classroom and as a "hands on" study, can compete with the excitement of dinosaurs and volcanoes. Geology has never had so early a contact with your people and leads us to hope that the next generation will be more comfortable with hazards, global warming and natural processes than the present one.

Eric Robinson
Geologists Association

January 2001