Geoarchitecture of some Romanesque churches in Aquitaine, France

Nouvelle-Aquitaine (New Aquitaine) is a vast region of southwest France covering more than 30,000 square miles. Between 1154 and the end of the Hundred Years War in 1453, much of the region was under British control. Links with Britain are still strong today, both through tourism and the large ex-patriate British population, particularly in the Dordogne, known jokingly to locals as ‘Dordogneshire’.

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Urban geology: The Boxtel wall game

Stephen K Donovan (The Netherlands) The Netherlands is a land of museums, approximately 1,200 of them in a country the size of southeast England. Although the major cities have an ample supply – about 30 in Amsterdam, for example – there are many and varied museums dotted throughout the country. (I remember, in 2003, being driven to Arnhem and seeing a German Panther tank parked outside a small military museum – be ready for the unexpected.) For the geologist, one of the gems is Het Oertijdmuseum (= The Prehistoric Times Museum; formerly De Groene Poort) in Boxtel, in the province of Noord Brabant, north-north-west of Eindhoven. As may be deduced from Fig. 1, the museum has a specialist collection of dinosaurs and other saurian – replicas in the gardens around the main building and mounted skeletons inside. Fig. 1. Welcome to Het Oertijdmuseum! I presume any visitor spots the glass fibre Tyrannosaurus before reading the notice on the right. Other saurians are lurking in the undergrowth around the main museum building, much to the delight of children of all ages. I am a walker and I prefer to saunter from the station through the attractive town of Boxtel to Het Oertijdmuseum rather than take a bus. The walk is a long 30 minutes. As you near the museum, the route passes a most extraordinary building, Bosscheweg 107, ‘Den Daalder’. This appears to be an entirely conventional office block until you reach the end closest to the museum, when all is … Read More

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Urban geology: A failed example of gabions as false urban geology from the Netherlands

Stephen K Donovan (The Netherlands) The provinces of Noord and Zuid Holland, including much of the Dutch North Sea coast and adjacent inland areas, are devoid of rocky exposures. In a region of flat-lying Pleistocene siliciclastic successions (Burck et al, 1956), there are no quarries, cliffs or other man-made or natural exposures of lithified rocks. The topography is slight, with the highest natural structures being the coastal sand dunes, in part preserved as a national park (Jelgersma et al, 1970). To offset this lack of geological ‘furniture’, the Dutch have enterprisingly imported and installed sundry rocks that fill what may be an unattractive void in the environment. These rocks vary from the minimalist, such as roadside boulders (in part, possibly erratics) (Donovan, 2015), to reconstructions of structures such as a replica of a natural bridge in Mississippian limestone slabs (Donovan, 2014). But, in some instances, reconstructions are unsuccessful or, at least, inaccurate, such as the false (Pennsylvanian) Coal Measure strata without identifiable coal beds in the national railway museum (Het Spoorweg Museum) in Utrecht (Donovan, 2018a). In this article, I describe further mock geological structures that fail in the details. Gabions are tools of the engineering geologist. Yet, when packed with cobbles of imported, grey Mississippian limestone, they may make convincing false sedimentary ‘beds’, at least from a distance, and are a not uncommon feature of the environment of Noord and Zuid Holland (Donovan, 2018b). (Vertical, dyke-like structures are rarer and are less successful as false geology; Donovan, research in … Read More

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Urban geology: A rostroconch in Hoofddorp

Stephen K Donovan (The Netherlands) Part of my job is to provide service teaching for the University of Leiden. The university lacks a geology department, but my colleagues and I provide tuition in stratigraphy and palaeontology for life science students at the undergraduate and masters degree level. One of my favourite practical classes is a building stones tour of a part of Leiden that is rich in Mississippian (Lower Carboniferous) limestones, which are packed with fossils. These have been used for facing stones, external stairs and paving slabs. Many have been in place for some hundreds of years and many have been etched by slow solution by rainwater as a result. Common fossils include crinoid columnals, tabulate and rugose corals, brachiopods, and molluscs (Donovan, 2016; van Ruiten and Donovan, in review). These are most commonly seen in two dimensions and random sections, a different view of life to what the life scientists are usually accustomed. One group of fossils in these rocks were a mystery until recently, but we now know they are sections through rostroconchs (Donovan and Madern, 2016, p. 349), an extinct group of Palaeozoic molluscs. Rostroconchs were formerly considered to be an ancient group of bivalves and they are certainly bivalve-like in appearance, but lack an articulation of interlocking teeth and a ligament. That is, the shell is a univalve, a one-piece structure. I had only seen the sections of rostroconchs in building stones in Leiden. It was therefore gratifying, shortly after publication of these fossils, to … Read More

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Urban geology: New Red Sandstone at Amsterdam Airport

Stephen K Donovan (The Netherlands) In a country with a limited resource of pre-Quaternary geology in outcrop, the Netherlands nevertheless has a wealth of rock types in building stones (Donovan, 2015a; Donovan and Madern, in press), street furniture (Donovan, 2015b) and artificial ‘outcrops’ (Donovan, 2014). Perhaps the commonest rock type seen in Dutch cities is limestone, particularly imported Mississippian (Lower Carboniferous) limestones (van Roekel, 2007; Donovan and Madern, in press), but also Upper Cretaceous limestones from the province of Limburg in the south of the country (van Staalduinen et al., 1979, p. 47). Less common are massive sandstones, both used as building stones and occurring as boulders (Donovan, 2015b) – most of these that I have seen are, presumably, Pennsylvanian (Upper Carboniferous). The area of outcrop of Carboniferous rocks in the Netherlands, again in the province of Limburg, is limited. Carboniferous rocks used for buildings or street furniture are assumed to come largely, probably entirely, from the more extensive outcrops that are quarried elsewhere. One rock type that is not commonly encountered is red siliciclastic rocks such as siltstones, sandstones and conglomerates. This is despite the broad distribution of the Permo-Triassic New Red Sandstone (NRS) in northern Europe (Hounslow and Ruffell, 2006, fig. 13.2). In my pursuit of river-rounded boulders in the human environment of the Netherlands, I have only seen one NRS specimen of note – a coarse-grained sandstone with abundant gravel-sized fragments truncated by a scoured, erosive contact with an overlying conglomerate (Fig. 1). This is at the … Read More

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Windmills and building stones: Antigua, West Indies

Stephen K Donovan (The Netherlands), David AT Harper (UK) and Roger W Portell (USA) In his 2014, Ted Nield (2014) reflects on building stones and what they tell the geologist about where they are. Once upon a time, building stones in Britain were derived locally and told the informed observer something of the local geology (apart from, of course, the exotic stones imported for banks and office blocks). That is, they were built of local stone from the local quarry. Today, stone is imported from as far afield as China, where once they would have been derived locally by horse and cart or canal boat. One place where local stone is still used is Antigua in the Lesser Antilles. For example, Jackson and Donovan (2013) described an attractive, green chloritized tuff, which is used throughout the island as a bright and distinctive building stone. Many old structures in rural areas are still constructed of stone, such as walls, buildings (including ruins) and, the subject of this article, disused windmills. For a general introduction to the geology of Antigua, see Weiss (1994) or Donovan et al (2014). All major stratigraphic units are Upper Oligocene; the regional dip is to the northeast. Betty’s Hope The Betty’s Hope site, in the parish of Saint Peter in eastern Antigua (Fig. 1), is an open air monument administered by the Museum of Antigua and Barbuda. Fig. 1. Outline map of Antigua (redrawn and modified after Weiss, 1994, fig. 3), showing the principal geological subdivisions and … Read More

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Urban geology: A sunny Sunday in Hoofddorp

Stephen K Donovan (The Netherlands) The last weekend in September 2013 was sunny after more than two weeks of grey skies, rain and even some fog. Saturday was spent as planned, moving bookcases ahead of Karen’s insatiable paintbrush, the walls changing from lime green to white as she progressed. Sunday morning was spent putting some books back onto bookcases, but I had to get out in the afternoon. It might be six months or more before I could venture out again in only a T-shirt, shorts, training shoes and floppy hat. I had my son, Pelham, as field assistant, but where to go? The answer was obvious to me – this was the day to consummate a project that I’d had in contemplation for some years. The Netherlands is not renowned for its pre-Pleistocene geology. There is the type Maastrichtian (uppermost Cretaceous) in the south, some fine Triassic near the German border in the east and odd spots of poorly exposed Tertiaries. Where I live, in Hoofddorp (near Amsterdam Schiphol Airport), we live below sea level on the bed of a drained lake; but what Hoofddorp lacks in surface exposure, it makes up for in building and ornamental stones. To the south and east of the town is a business park in the Beukenhorst district, with a fine range of architectural styles and building materials, both man-made and natural stone. One road, Siriusdreef, in this part of town has intrigued me for years. Street art is widespread in the Netherlands … Read More

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Urban geology: Monumental geology

Stephen K Donovan (The Netherlands) My writings on urban geology are normally centred in the area around my home in Noord Holland, but sometimes I am lucky enough to travel. A personal wish that I have had since I was a teenager was to see and, if possible, board a dreadnought battleship. This whim was finally satisfied in March 2014, when I visited the last surviving dreadnought from World War I, the USN Texas, preserved at the San Jacinto Battleground State Historic Site, near Houston (Fig. 1A). What I had not realised was the battleship is interred adjacent to the site of the Battle of San Jacinto, where a rag-tag army of insurgents, following defeat at the Alamo and Goliad, decisively defeated the Mexican army in under 20 minutes in April 1836, thereby winning independence from Mexico for Texas. Fig. 1. Two breathtaking exhibits at the San Jacinto Battleground State Historic Site, near Houston, Texas. (A) The dreadnought battleship, USN Texas, commissioned in 1914 and a veteran of two world wars. (B) The San Jacinto Monument, built in 1936 from Cordova Cream Shellstone and the tallest memorial stone column. The San Jacinto Museum of History is in the base. The Battle of San Jacinto is commemorated by a towering monument (Fig. 1B), which is the tallest memorial stone column, about 175m, and some 4.5m taller than the much better known Washington Monument in Washington DC. The San Jacinto Monument is visible over a wide area of this flat coastal plane … Read More

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Urban geology: Palaeontology at the Wagamama restaurant, Amsterdam

Stephen K Donovan (The Netherlands) A misconception shared by many non-palaeontologists is that fossils are rare. For example, when governments pass legislation to protect their fossil heritage, they are stopping the export of complete and well-preserved specimens, such as those of Mesozoic dinosaurs, hominids and Ice Age mammoths. There can be little argument that protecting their prehistoric heritage is responsible. Yet, these same politicians will support, for example, the export of cement. This may seem unrelated, but, of course, limestone is rich in fossils, most particularly invertebrates (Bathurst, 1971), and is an essential component of cement. These fossils are not dinosaurs or mammoths, admittedly, but they are fossils nonetheless. Legislation needs careful wording to ensure that exporting cement is not an illegal activity. Fig. 1. Imported rocks used in raised flowerbeds and paving at Amsterdam Zuid (=south) railway station, the Netherlands. (A) General view. The grey stone is Carboniferous limestone; the pink stone is gneiss. The Wagamama restaurant is to the left of the photographer. (B) Detail of the upper surface of limestone on a raised flower bed. The fossils are dominantly fragments of crinoid and a colonial tabulate coral (Michelinia? sp.) is seen towards the bottom of the page and a section through a productid brachiopod(?) is right of the coin. The coin is €2, about 25mm in diameter. The Netherlands is an exporter of cement from the Upper Cretaceous limestone quarries in Limburg, in the far south of the country (Felder and Bosch, 2000) and therefore trades fossils … Read More

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Urban geology: Boulders and the Dutch

Stephen K Donovan (The Netherlands) My late wife, Dr Trina MacGillivray, was a geomorphologist. She loved the Netherlands and the Dutch landscape, but more than once made astute comparisons with the scenery of other northern European countries. The Dutch landscape, if it has a fault, is too organised, too well arranged and too manicured. Woe betide the blade of grass that dare step out of line. Trina’s observations extended to Belgium. If travelling to Brussels by train, it is immediately obvious when you have crossed the border because the landscape relaxes. It is not unruly or untidy, but, unlike the Netherlands, it does not need to maintain a near-geometric precision. Trina liked her trips to Belgium, too. These memories were revived on a recent bus ride from Leiden to Hoofddorp, near Amsterdam Schiphol International Airport. It was a grey, overcast day – the sort of dreary weather that the Netherlands does too well and too often. Even before we had left Leiden, the regular geometry of the town impressed itself on me. But then there was something in the central reservation that caught my eye – a cluster of irregularly rounded boulders of various lithologies (Fig. 1E, F). It occurred to me then that such clusters of boulders were not so unusual in the Dutch landscape, breaking up the geometry in unusual ways (Figs. 1 to 3), yet were undoubtedly man-made. Fig. 1. Boulders in Leiden, 4 February 2015. (A) The boulder garden, a favourite of all children who like … Read More

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