Through The Sandglass

Rippled Roads - the granular physics of washboards

Leaving the tarmac, anywhere in the world, is liberating. For a geologist, a dirt road is often the highway to fieldwork and all its pleasures, satisfactions, frustrations, and challenges. You set out, going through in your mind the plan for the day, with the window down and a rapidly growing sense of isolation and freedom; the road is good and straight, and you speed up, the hills in which the day's challenges lie coming increasingly into focus, that one outcrop that will reveal all beckoning you on - and then, suddenly, there they are in front of you, corrugations, a washboard road, the strange behaviours of granular materials rearing their ugly heads. You slow down, and it's excruciating, both physically and mentally. To avoid this, there are two choices, the first to drive at a glacial pace, around four feet a fortnight or so it seems. This is, of course, intolerable, so you elect for the more thrilling approach - you accelerate to the point where the washboard only generates a sort of background massaging vibration as you fly over the corrugations with little or no traction at all, dry aquaplaning in the clouds of dust.

I did years of fieldwork in the glorious lonesome country of the northern Nevada basin and range; it was some of the most enjoyable time that I've spent in the field, but boy did I get to know washboard roads. Entire stretches of road across the broad valley floors would be smooth, only isolated stretches corrugated, or the whole journey would be over a washboard. Why does this happen, inevitably, to dirt roads (and train tracks and ski runs, for that matter)? The corrugations look like ripples in the sand, regularly spaced, asymmetric, and of a constant bone-shaking amplitude. Conventional wisdom for a long time decreed that it was all to do with driver behaviour, vehicle speed, characteristics of the suspension and tires, weight, wind, and the grain sizes of the gravel and sand used on the road. But then why are the corrugations so uniform? And why, despite many attempts, did the design of a non-washboarding road elude the best engineering minds? Well, it turns out that the phenomenon is quite simple, and like anything to do with granular materials, at the same time immensely complex. Back in 1993, Keith Mather, former director of the Geophysical Institute at the University of Alaska, Fairbanks, reported on a simple experiment that demonstrated that the corrugations build spontaneously in a bed of sand, however apparently smooth the starting surface, when a simple wheel rolls continuously over it (http://www.gi.alaska.edu/ScienceForum/ASF12/1291.html).

Then, a couple of years ago, a team from the Universities of Toronto and Cambridge published the results of an again simple experiment and quantitative numerical simulations of what is going on. In the experiment, they simply rolled a free-floating hard rubber wheel around and around a circular bed of smooth sand (photo, right). Above a critical velocity (around 1.5 meters per second, an intolerable 3.5 miles an hour), ripples developed spontaneously and spread around the circumference of the sand, migrating in the direction of the wheel's motion, but retaining a regular amplitude and frequency. They repeated the experiment with different materials, different ranges of grain sizes and demonstrated that these make no difference, and that compaction and segregation have nothing to do with the result. Using the mathematical modelling approach of the "soft-particle Discrete Element Method" (beyond my skills to explain further, but see the references below), they replicated the experimental results and were able to analyse the internal structures and evolution of the ripples (illustration below).

Washboard roads are the result of the spontaneous - and bizarre - behaviour of granular materials; if it's any consolation as you shake yourself and your vehicle to pieces, the physics involved is, once again, non-linear and driven by power laws (see the January 11 post, "Granular stuff, earthquakes, and power laws - again").

Of course, no awareness of non-linear granular physics would have changed what happened to me on a washboard road many years ago. It was dusk, after a good day's fieldwork, and I was heading back to my motel room in Battle Mountain, driving fast over the corrugations, a shower and a beer, and maybe a game of pool, all luring me on. In the gathering gloom, I saw too late the shallow ditch excavated across the road in front of me. I hit it full tilt, hammering my head into the roof, and the truck took to the air, coming down with a crash and two exploded tires. Fortunately, as was my quite sensible habit, I had two spare wheels with me. The beer was somewhat delayed. 

[Details of the research, including videos, see the website, from which the illustrations are taken,  http://perso.ens-lyon.fr/nicolas.taberlet/washboard/, and the complete pdf at http://www.physics.utoronto.ca/~nonlin/preprints/TMM07.pdf. There is also a good Science News summary: http://www.damtp.cam.ac.uk/user/jnm11/media/sciencenews-2007-08/www.sciencenews.org/articles/20070818/fob7.asp.]

A small celebration, and another fully-equipped geologist

A brief break from my normally arenaceous topics to pause and reflect on the first four months of this blog. I've just finished a total of fifty posts - not exactly a frenetic rate, I know, but a landmark for me nevertheless. And while Through the Sandglass occupies a sort of blogoplanet of its own in terms both of its subject matter and the modest number of visitors compared to much of the rest of the blogosphere, it has developed a truly international reach. I have very much enjoyed it, learnt a lot myself along the way, and "met" all sorts of interesting people; I'm grateful to the regular visitors and commentators and look forward to the growth of this devoted band.

For anyone who happens upon this blog and is looking for a sense of what it's about, here is a short list of posts that I particularly like, a sort of top eleven which, I hope, illustrate the intended diversity of topics (the celebratory wordle above includes the majority of key words):

• Evolution - organic and inorganic
• Sand, Earth Systems, and the Importance of Size
• Grain-by-Grain (1): worm superglue
• Grain-by-Grain (2): the amazing sand bottles of Andrew Clemens
• The man who figured out how deserts work
• Of Mice and Sand - Evolution in Action
• Building New York - the Long Island Sandminers
• From Bogart to Bugs - the Angle of Repose
• Magic Crystals - Tales Zircons Tell
• tafoni
• Sandstones of Barcelona (2): Gaudi (and tafoni again)

And, on a light-hearted note, there's been another "meme" around the geoblogosphere over the last week - depictions of what a "fully-equipped field geologist" looks like. Started by The Lost Geologist with contributions from all kinds of sources, including Hypo-Theses, Nologic, Pools and Riffles, Looking for Detachment, and others from the blogroll on the right. So here's my - distinctly archival - contribution to illustrate other necessities.

 

Perhaps a few words of explanation are needed. This was 1967, the first of two seasons of undergraduate fieldwork in the Arctic - Spitsbergen, or Svalbard, to be exact. The Cambridge expeditions were famous and famously frugal - the tents were named after Nansen and seemed to date from not long after him. The solution was to gather driftwood and pieces of blown-down trappers' huts (including a stove) and rig up a communal shelter, the Hornsund Hilton. The Johnnie Walker scotch was the single bottle issued for the season, so its opening was an event - I discovered that sea ice still contains salt. There were, of course, other items of field equipment, including a rifle and a radio - but the generator blew up and we spent the entire summer out of contact with anybody. But now I'm in danger of launching into my series of "Welland of the Pole" stories that my wife so enjoys.....

[a couple of years ago, Geoexpro had a piece on geotourism in Hornsund and kindly published a short historical piece I submitted -  read more here if you wish]

Rivers again - sandbags in the Red River Valley

Last Sunday was World Water Day, highlighting the global issues associated with this precious resource. But one of those issues is, as with all natural resources, its distribution, and for the residents of the Red River Valley it's a case of definitely too much of a good thing, battling as they are against rising flood waters. As I write this, predictions are varying, but the river, along the border between North Dakota and Minnesota and northward to Winnipeg (it's sometimes referred to as the Red River of the North to distinguish it from the Texan one), is likely to crest up to 20 feet above flood level over the next few days. The residents of Fargo need to fill two million sandbags. It is, so to speak, all hands to the pump, with volunteers coming from all sections of the community - people who have delinquent fines or outstanding arrest warrants have been given a chance to get them withdrawn if they sign up for sandbag duty. Three "spider machines," shown in the photo at left, above, have been set up to fill sandbags at a rate of 5,000 each every hour, but much of the effort still relies on traditional methods (photo right, above).

There is geological irony here, for the circumstances that make the valley prone to disastrous flooding (the 1997 inundation caused $3.5 billion in damages and required large-scale evacuation) also provide the sand for the sandbags. During the ice ages, glaciers marauded ponderously across North Dakota and Minnesota, scouring and sculpting the landscape and leaving vast swathes of geological debris in their wake. As they retreated and rivers (amongst them, the Red of the North) re-established their courses, a huge lake built up in front of the ice - Lake Agassiz, named for the great Swiss-American geologist who deciphered the stories of glaciation. The map below shows the maximum regional extent of the waters of the lake - they never covered the entire area shown at one time, but the position of the lake shifted as the ice retreated. Today's Red River follows the western shoreline of the lake, and its wide flat valley reflects its origins as as an ancient lake floor. Rivers reworked the glacial sediments and poured huge volumes of sand and gravel into the lake; along the shoreline, deltas, beaches, and shallow water sandbars formed that today provide, among many other things, the filling for the sandbags.

President Obama has declared North Dakota a federal disaster area - let's all hope that, for the communities of the Red River Valley, sand prevents the worst.

[sandbagging photos from http://minnesota.publicradio.org/display/web/2009/03/20/fargo_dikes/; Lake Agassiz map from the Geological Association of Canada, available from the University of Manitoba Libraries Map Collection, http://www.flickr.com/photos/manitobamaps/2091302531/in/set-72157603391175172/. For a good summary of Lake Agassiz, see the North Dakota Geological Survey document at https://www.dmr.nd.gov/ndgs/ndnotes/Agassiz/Lake%20Agassiz.asp]

Clogged Arteries - natural and unnatural rivers

Rivers are vital but also complex and dynamic systems - vital for the planet and vital for us. Civilization has always had an intimate relationship with rivers. They provide habitable areas, transportation and communication routes, food, power, and constantly replenished agricultural land. But river systems in their natural state are sensitive to slight changes in climate and sea level and change their courses routinely - when we interfere with this, things become even more complex and unpredictable and the course of history, as well as that of a river, can be changed.

I have just spent a very enjoyable couple of days in around the city of Narbonne, on the Mediterranean coast of France between the mouth of the Rhone and the Pyrenees. It was enjoyable in many ways - Roman history, great wines, mountain and coastal landscapes, excellent food. I had with me, for occasional reading, the March issue of Earth magazine, in which there is a fascinating article on the work of Franklin and Marshall College geologists Dorothy Merritts and Robert Walter. "Rewriting Rivers - did we get it wrong and what might that mean for river restoration?" underlines the complexity of river systems, and how much, putting aside conventional wisdom, we actually don't know about them. The behaviours, geomorphology, and sedimentology of Countless rivers in the eastern US are controlled by the history of dam building. By 1840, more than 65,000 mills had been built, each with a dam and a millpond collecting sand and silt. After the dams are removed, it is those "legacy sediments" that influence the river's development. The pre-settlement sediments tell a very different story of the river systems - and one that does not necessarily fit with conventional wisdom. And around Narbonne, I found myself in the midst of another historical drama of man and rivers.

To the east, between the city and the coast, is the limestone massif of the Montagne de la Clape (please resist any temptation to indulge in sophomoric humour). The photo at the beginning was taken from there, looking back towards Narbonne in the distance, the great bulk of its unfinished cathedral visible against the dark hills of the Corbieres. The massif is rugged and dry, a fault-bounded up-thrown block that hosts what are reputed to be the hottest and driest vineyards in France -  but the gnarled and dessicated-looking vines thrive in this terroir, and produce some wonderful syrah-rich wines. If, however, the view from this spot was that of eight hundred years ago it would have been dramatically different - I would have been standing on an island and looking east across the shallow waters of a branch of the Mediterranean, and Narbonne would have been a commercially thriving port. It had indeed been a port since its glory days as the major capital of the Roman Empire west of Rome, at the crossroads of major Roman roads (a section of the Via Domitia can be seen today, eerily and evocatively, in the town square). It exported to the Empire linen, hemp, oil, wood, pottery, cheeses and meat - and, yes, of course, wine. Building stones from all parts of the Empire were shipped into the harbour to build the great city. The port was at the northern end of a branch of the sea where the River Aude then emptied into the bay - but the Montagne de la Clape was not an island - another branch of the Aude ran north of the mountain, depositing its sediments in a broad coastal plain (see the top map at right). The Romans also began what would be an ongoing engineering enterprise for the region - canal-building. The Roman Empire fell to the Visigoths, the Visigoths fell to the Saracens, and the Saracens fell to the gloriously-named Pepin the Short. And for some time before the beginning of the thirteenth century, rivers had changed their itineraries, sea levels had risen, and the Montagne de la Clape had become an island (central map).     

But the good times were coming to an end. To compound the effects of the Black Death, the assaults of England's Black Prince, and the expulsion of the flourishing Jewish community, Narbonne suffered a natural disaster - the Aude shifted again. The harbour was filled with silt and sand, and sand bars blocked off the southern branch of the sea, forming the lagoons we see today. The main branch of the Aude chose the northern route, emptying into the Mediterranean north of la Clape and supplying the volumes of sand that were swept down the coast to form today's tourist beaches, and the spits and sandbars that continue to block the lagoons. Narbonne sank into terminal decline.

By the late seventeenth century, commerce to the north was being resuscitated by the completion of the Canal du Midi, the extraordinary feat of engineering that linked the Atlantic with the Mediterranean. This was immediately followed by an attempt by Narbonne to plug itself back into the communications network, and the Canal de la Robine was constructed, following an abandoned course of the Aude, to link northward into the Canal du Midi system. But this conspiracy of the Aude's natural options with the complexities of the canals linking with the river and each other, permanently changed the sediment budget for the region. The lagoons became increasingly isolated from the sea and the Canal de la Robine was extended southwards through the sand barriers to provide a link with the Mediterranean. The lagoons provided an ideal setting for the salt industry that continues today.

When I took the photo that heads this article, I studied the local topographic map, one of the superb 1:25,000 series that the Institute Géographique National produces. In the fields and vineyards that today fill the middle distance, the site of the old branch of the Mediterranean, local names still record, for example, the Ancien Étang du Cercle ("étang" is a lagoon), and l'Étang Salin - names that come down to us through history recording dramatic changes to the landscape that occurred, not in geological time, but our time.

[maps from Géologie du Languedoc-Roussillon, Jean-Claude Bousquet, BRGM, France]

Ochre - the Colorado Provençal

A hundred million years ago, today's Mediterranean didn't exist. Continental bits and pieces that would become Spain, Italy, France, and the whole geological jigsaw that we see today jostled around in balmy tropical seas at the western end of the great Tethyan ocean that separated Africa from Asia. This ocean would later be consigned to the geological graveyard of the Alpine Mountain system, but, during much of the Jurassic and the Cretaceous periods, things were relatively peaceful. Tropical seas are limestone factories, and sometimes, wandering around the Alps, you can't help but wonder whether anything other than the carbonate cycle was going on -seemingly endless landscapes of limestone, now twisted and exhumed, dominate the scenery, as in the hills in the background of the photo above. But what's that in the foreground? Clearly something else was going on - rivers, coasts, and dunes were accumulating sands that would provide a brilliantly colourful relief from the gray limestone hills.  

The brilliance of the palette of these sandstones in Provence, at the southern end of the exposed Alps, is the product of the alchemy of geochemistry and mineralogy, and this is one of the largest deposits of ochre in the world. The sandstones contained iron-rich clays between the sand grains and the conspiracy of time and water moving through the sands changed those minerals into a variety of other clay minerals, many with not only exotic names but also exotic hues. This is the area of the Luberon, around the hilltop village of Roussillon (distinct from the region of Roussillon to the south where I'm currently enjoying warm March sunshine). Ochre has been quarried there for millenia, and, at its peak towards the end of the nineteenth century, seventeen different tints were extracted and exported worldwide. The area became known as the "Colorado Provençal" (colorado being one of the Spanish words for red, hence the US state) and today you can walk any number of trails amongst the old quarries and the outcrops of ever-varying colours - purples, yellows, browns, reds and oranges.

 

The French geological description of these sandstones refers to their originally containing the green mineral glauconite, a complex hydrous silicate of iron that commonly contains a range of other ingredients - aluminium, magnesium, calcium, and so on. It was the glauconite that got caught up in the alchemy and changed into a variety of iron-dominated rusty minerals, goethite, hematite, limonite. Each of those rust minerals has a different colour, but the spectrum is also influenced by the size of the grains and their differing ways of interplaying with light. The sandstone, as can be seen in the photos above, display a variety of sedimentary structures, including dramatic cross-bedding, suggestive of rivers and dunes. Now glauconite is a mineral that is generally regarded as forming in the calm waters of shallow seas, but these sandstones do not have the appearance of having been deposited in such tranquil environments - was the glauconite perhaps eroded out of other (marine) sandstones and transported along with all the other detritus that ended up as the sands of the Colorado Provencal?

Ochre has long been used as a pigment, mixed with natural oils, both for prehistoric art and body ornamentation; it was used by ancient Egyptian women as rouge and lip gloss, and the ancient Picts (and "Red Indians"?) coloured themselves with blood-red ochre. Ochre dyes were used to preserve the canvas sails of English fishing vessels, and it may have contributed to the processes of treating hides. Ochre has been used lavishly in burials from cultures all over the world, and it would seem that this may reflect  practical, as well as symbolic, properties. It was used by the Egyptians in the mummification process and in two thousand year old burials in North America; it is used today by native Australians to heal wounds and burns. Ochre would seem to be natural antiseptic.

And, of course, ochre is still used as a painting ingredient today. Visit the dazzling landscapes of the Colorado Provençal, and you can buy sets of natural pigments. Look in art supply catalogs and you'll find endless varieties of ochre colours. The alchemy of geochemistry and mineralogy is wonderful - no wonder Andrew Clemens could find all the coloured sand grains that he needed (see my Jan 9 post).

 

Rugby: England 34, France 10

Right, a new category for this blog - sport. I tend, not surprisingly, to collect images that use sand in any way, and the picture above comes from an advertising campaign last summer by the major sponsor of the English Rugby team. The campaign was designed to promote interest in the game amongst the country's youth by setting up beach festivals where England players would show up, sometimes in exotic costumes. The campaign culminated on an urban beach in London. Now, given that English rugby had just suffered a series of humiliating defeats in the southern hemisphere over the summer, it struck me that an image of the sport based on sand, not the most tough or durable construction, might stand me in good stead for the winter internationals (although, of course, I hoped not). After further defeats and endless hand-wrung column inches in the press, and accusations flung around about the ability of the new coach and manager to coach and manage, we came down to yesterday's match, always one of the high profile and emotional conflicts, England versus France. Aha, I thought, time for the resonance of my sand image. And I'm in France right now, so, for a match billed in advance as "le crunch," I was prepared for putting up with the far-from-impartial enthusiasm of the French TV commentators, the triumphant headlines in today's newspapers.

BUT, in an extraordinary game, England not only won, but, to put it bluntly, thrashed the French (they were leading 29-0 at half time). The headline in the sporting press is shown below. In other reports "le crunch" became "le crash," and humiliation was a commonly used word. So, it was just a game, and does not necessarily signal the renaissance of English rugby - but what a game!

I should mention, for American readers, that yes, rugby is peculiar in some ways (being required to throw the ball backwards does not make immediate sense), but it is a great sport. I am, after all the years I spent in the States, a fan of American football (should I admit, the Philadelphia Eagles?), but I remain an ex-rugby player at heart; and you could watch two rugby matches in the time it takes to get through one NFL game.  

And one more connection between rugby and sand. Points can be scored by kicking the ball between the posts, the ball being placed these days in a kicking "tee." But it was not that long ago that the ball would be set up for the kick by an assistant running on to the pitch with a bucket of sand, out of which the kicker would build a small pile into which he would carefully embed the ball.

Invading dunes

Dunes move - it's what they do, it's what makes them dunes as opposed to lifeless piles of sand; and nothing will stand in their way. The images above are of dune invasion in the Bahariya oasis of Egypt's Western Desert, but to see a moving National Geographic video of the human cost of dune encroachment, follow the link at http://geology.com/news/2009/shifting-sand-dunes-bury-homes.shtml.   

The video is from Mauritania, but in towns and villages throughout the Sahara, houses engulfed by sand are abandoned, to be reoccupied, perhaps by the next generation of the family, after the sand dune has moved over and onward. Fields and palm groves are treated the same way—but the palms will be dead and new ones will need to be planted. Huge amounts of money have to be spent keeping roads and railways clear of sand or rebuilding them. There are ways of inhibiting the march of the dunes - but I'll leave that fascinating topic for a later post.

Arawan, the once-thriving oasis north of Timbuktu used to serve the camel caravans from the salt mines further north, but for a long time now the visitors have been dunes rather than traders. And the women of Arawan shovel sand, every day when the wind is not blowing too hard. It’s not that they haven’t always lived with sand, being, after all, in the middle of the Sahara; but in the 1960s and early 1970s a series of devastating droughts destroyed much of the vegetation, and the sand began to move. The mosque was buried, trees were engulfed, and the wells had to be reexcavated. Dunes encroach on the roofs of houses, the owners keeping only the doorway clear. The sand women are professionals, often paid in rice or sugar to shovel the surrounding dunes, energetically but for the most part futilely.

The video discusses desertification. Moving dunes do not signal desertification, but expanding seas of sand, the ergs of the world, do. It's a controversial topic and the evidence for desertification around the fringes of the Sahara is not always clear-cut. What is clear, however, is that where the Earth's arid regions are expanding, where desertification is taking place, more often than not it's our fault - and not through climate change. The most dramatic, and potentially catastrophic, example is that of China. More than a quarter of the total area of China, over 2.5 million square kilometers (a million sq mi)—about four times the area of the state of Texas—is covered by deserts. Four of these—the southern Gobi, the Alashan, the Taklimakan, and the Tengger—are more or less connected to form the vast arid interior. The total area of China’s deserts is growing at around 200 square kilometers (80 sq mi) every month, and every year tens of thousands of tons of sand and dust are blown into Beijing. China’s capital has always suffered from dust storms, helped again by the ice age, when grinding glaciers wore rocks down to flour, technically known as loess, which, once airborne, blankets huge areas for long periods of time. But Beijing’s dust storms are turning into sandstorms. It’s not necessary to travel to the Gobi Desert to find encroaching sand; it’s a mere hour’s drive out of Beijing. The Great Wall, built to defend against invaders from the west, is proving no match for the onslaught of sand: whole sections are being destroyed by the storms.

In the village of Longbaoshan, dunes are consuming the houses, and digging has become a way of life. In the region where forests and lakes once provided the hunting grounds for emperors, sand dunes move across the landscape at 20 meters (65 ft) per year. Entrepreneurs have benefited from tourists and filmmakers traveling to Longbaoshan from Beijing in quest of desert landscapes, but a villager's narrative brings us back to the human cost: “Sometimes I dream of the sand falling around me faster than I can dig away. The sand chokes me. I worry that in real life, the sand will win."

Today’s inhabitants of villages like Longbaoshan can point to dusty, bare hillsides and valleys that they remember being verdant. It is estimated that firewood collection, excessive grazing, and overcultivation account for close to 90 percent of recent desertification. For many areas of the world where sand is threateningly on the move, it is not nature, but humans that are the cause, and, as for the woman in the video, it's humans that suffer the consequences.

[fora good article on Longbaoshan and Chinese desertification, see http://www-cgi.cnn.com/ASIANOW/asiaweek/magazine/2000/1013/is.china.html; the quotation is from this source. Photos by myself and Google Earth]

Official vindication

Writing a book is a journey - and mostly a roller-coaster one. During the long period that I was working on Sand, I learned to be discerning and discreet about who I chose to mention it to. I was often reminded of the story of Peter Cook, the dour and endlessly funny British satirical comedian of some years ago, who, in a pub, was collared by a fawning acquaintance. The man declared to Cook that he was writing a book; "Oh really?," Cook responded, "Neither am I." I shall also never forget the occasion that I mentioned to an old friend that I was working on a book. Her face lit up with curiosity and enthusiasm, and she asked what it was. "It's all about sand" I replied, at which her face instantly drained of any sign of animation, and took on the definition of the glazed look. Her reaction was not dissimilar to that of any number of publishers.

But last week, a couple of American friends were visiting London and suggested that we go to the geological exhibits at The Natural History Museum. I hadn't been in heaven knows how many years (why is it that, when one has the privilege of living in a great city, taking advantage of what it has to offer mainly occurs when folk come to visit?), and, I have to say, I much enjoyed it. The highlight for me was, without doubt, entering the "Earth's Treasury" gallery, a spectacular and accessibly informative display of our planet's resources. At the entrance to the gallery was the sign below - I caused a minor disturbance when I read the last line.

Sandstones of Barcelona (2): Gaudi (and tafoni again)

 

The Montjuic sandstones (March 5 post) that built, and rebuilt, Roman and medieval Barcelona went on to play a starring role in the wonderful, eccentric, stunning, creations of Antoni Plàcid Guillem Gaudí i Cornet. Barcelona and Gaudi are inextricably linked, and a visit to the city feels in some ways like a pilgrimage. This was my first visit (a return is necessary, having only sampled some of the highlights). Although I knew Gaudi's work, of course, from books, images, and friends' descriptions, it remained distant and beyond my grasp - I had no clear idea of what it really was. It's an architecture that can only be accessed directly and personally, through touch as well as vision. And where to start on this experience? Again like a pilgrimage, there is a compulsion to start with the icon of Barcelona, Gaudi's greatest and yet-unfinished masterpiece, the Templo Expiatorio de la Sagrada Familia. I am no architectural expert, and the details of the history and symbols of the Sagrada are easily available elsewhere; I shall simply try to describe what fascinated me about the church, and, indeed, all of Gaudi's creations - the inspiration, the materials, the forms and the design. And I should make it clear that I don't approach the Sagrada, or any church, through the eyes of religious faith, but rather through the eyes of a faith in human nature, creativity, inspiration, capacity. And, of course, through the eyes of a geologist.

Gaudi took over the building of the church in 1883, a year after it was started as a conventional gothic design; he radicalized it, sculpting into reality his extraordinary visions of naturally-inspired design, together with the innovative construction techniques that these visions demanded. The building became his passion; he lived and worked like a hermit within its embryonic structure, designing, calculating, modeling, redesigning, and starting over. When he died in 1926, run over by a tram, he was impoverished and unkempt, unrecognized in the paupers' hospital to which he was taken. The church was perhaps a quarter finished. The work continues today, made possible by the capabilities of modern design software, the extraordinary creative skills of today's craftsmen - and a continuing shared passion.

The Montjuic sandstone forms the bones and the flesh of the building, providing, together with sculptures from its cousins in Lleida to the west of Barcelona, the flowing organic forms of the Nativity Façade (right) and the glowing, soaring structure of the Passion Façade (left) - appropriately named even by the secular use of the word. But the quarries on Montjuic were closed many decades ago, and the stone, even recycled, is scarce. For some elements of the structure, specialty concrete is used, the sand content carefully selected to harmonize with the natural sandstone; this has been controversial, vigorously condemned by the purists - who choose to ignore the fact that Gaudi himself was using reinforced concrete for some of the early construction, since the stresses and strains some of the radical design elements necessitated its use. In today's project, the methods used are on the cutting edge of concrete design and construction.

The Sagrada is nothing but curves, light, colour, and space, made possible only by Gaudi's creativity and his seemingly intuitive grasp of the mathematics of form. The columns, inspired by the structure of trees, vary in form according to their position and role; their shapes twist and counter-twist in ways that it took considerable effort by modern minds (and computers) to understand. They are cored by reinforced concrete and faced with natural stone - the Montjuic, together with basalts and granites. The interior is staggering, quite literally awe-inspiring (below). But, as I have already said, photographs don't do it - you have to be there, feel the place for yourself.

The Montjuic sandstone is joined for some of the interior elements by Scottish sandstone from the Clashach quarries on the Moray Firth. A "New Red" sandstone from the desert dunes of the Permian Period, some 250 million years ago, it is famous for its preservation of the tracks of ancient (and doomed) reptiles, all very geologically different from the Montjuic. But the two are similar in important ways. The Clashach sandstone had been used during refurbishment of Barcelona's old cathedral, and came to the attention of the Sagrada architects because of its similar appearance to the Montjuic, the warmth of its colour, its texture, and its durability. Its distinctive character has also led to its being featured in the British Memorial Garden to 9/11 victims in New York's Hanover Square.  

I could add much more on the glorious design, the materials, and the fascination of the place, but enough - if you haven't seen it, you must. The Templo Expiatorio de la Sagrada Familia is a temple - to creativity, inspiration, passion, and skill.

After the Sagrada, a break to catch the breath, a non-Gaudi interlude, is recommended. But then go to his other icons, those of domestic architecture, the Casa Mila and the Casa Batlló. The first has also been named "La Pedrera," the stone quarry, and the second, the "House of Bones," reflecting perceptions of the character of their design. The quarry in question for Casa Mila is in Vilafranca del Penedes, and it provided the Catalonian limestones for the façade; the undulating form of that facade (below) has stimulated much metaphorical hypothesizing with respect to its inspiration - ocean waves, desert dunes, and the sculpted weathered sandstone terrain around the monastery of Montserrat, northwest of Barcelona, are among the most popular. And then, on the extraordinary roof terrace, appear the strange forms of the chimneys that were said to be the inspiration for Darth Vader and his troops......

But to return to Gaudi and his beloved Montjuic sandstone, a visit to the Casa Batlló is needed. The existing building was completely redesigned by Gaudi, essentially straight out of his imagination; its almost hallucinatory façade (the yawns or the bones) is inspired by St. George, the patron saint of Catalonia, and, more immediately, the dragon (left). There are no straight lines in the flowing sandstone of the facade - or any where else in the building, for that matter. Every detail was designed by Gaudi, down to the window handles and each piece of stained glass, each tile, every idiosyncrasy. Every individual element of Gaudi's design is fascinating and unique; sometimes, in juxtaposition en masse, they become overwhelming.

But the curves and the flow and the outrageousness of the designs are compelling, each often personally evocative of those endless metaphors of natural forms. At the Sagrada was a small exhibition with examples of natural architecture that appear in Gaudi's designs - trees, leaves, spirals, the Fibonacci series, twinned crystals, and weathered landscapes. Tafoni (my 22 February post) were strangely not included, but they should be. Below are two examples, the gates of the entrance to La Pedrera and the façade of the Casa Batlló - for the latter, when I took the image of tafoni in the Santa Cruz Mountains of California (credit below) and simply overlaid it on the facade of the House of Bones, I admit that my jaw dropped. 

 

And Salvador Dali described the modernist architecture, and that of Gaudi in particular, as "the patisserie of Barcelona", so I will end with one final metaphor.

[all photographs are my own, except for the image of tafoni in the El Corte de Madera Creek by Vicki and Chuck Rogers, creative commons license, http://www.flickr.com/photos/two-wrongs/104484095/in/set-516287/]

Carnival of the Arid

Apologies to Chris Clarke at Faultline/Coyote Crossing - through senility, distractions, or any number of other excuses, I completely forgot to post a link to his latest Carnival of the Arid. There's a great diversity of items of interest there - including Chris's own poem, Alluvium, that takes a creative look at earth processes - I really enjoyed it. Anyway, better late than never (I hope) - here's the link.