Through The Sandglass

Dune mysteries and other Mars news

A friend sent me the link to this image (without annotations), yet another spectacular and provocative high-resolution image of Mars. The crest of each dune runs along the boundary between the light and dark blue-gray flanks, and the surface between the dunes is covered in boulders. However, I have a slight problem with this and would appreciate other views. Here's the caption that goes along with the image:

Dunes of sand-sized materials have been trapped on the floors of many Martian craters. This is one example, from a crater in Noachis Terra, west of the giant Hellas impact basin. The High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter captured this view on Dec. 28, 2009.

The dunes here are linear, thought to be due to shifting wind directions. In places, each dune is remarkably similar to adjacent dunes, including a reddish (or dust colored) band on northeast-facing slopes. Large angular boulders litter the floor between dunes.

(Image Credit: NASA/JPL-Caltech/University of Arizona;  http://www.nasa.gov/images/content/418311main_mro20100113-full_full.jpg)

Now, the fact that "large angular boulders litter the floor between dunes" is not the problem - on our own planet, one of the extraordinary things about dunes is the way in which they seem to self-accumulate and hoover up all the sand from the clear, rubble-strewn "streets" between them. It was Ralph Bagnold who set us firmly on the path to understanding why and how this happens - bouncing versus splashing. I saw this phenomenon very clearly in Bagnold's old stomping grounds of Egypt's Western Desert, as shown in the photo below - vast areas of pebbles and larger rock fragments, essentially swept clear of sand and encroached on by the flanking dunes.

If you cross the dunes, the only rocks to be found on them are either meteorites or surplus tossed out by a passing geologist. And therein lies my problem. Look closely at the Mars image - for example, the two areas that I've magnified - and very large boulders appear to be lying well up the flanks of the dunes, on the surface of the sand and clearly influencing the pattern of ripples around them. What's going on here - or am I misinterpreting something? (As is common, NASA frustratingly disdains providing a scale).

This is a good time to be celebrating the wonders of the Red Planet, because right now it's particularly close to us. As reported in Wired Science:

On Jan. 27, Mars will be closer to Earth than any other time between 2008 and 2014. A mere 60 million miles away, the red planet will be a great target for backyard telescopes, and will appear bright to the naked eye as well.

Every 26 months, the two planets’ orbits bring them closer together, sometimes closer than others. In 2003, Mars came within 35 million miles of Earth, a 60,000-year record.

Observers with a telescope will be able to see changes over the north pole of Mars as the carbon dioxide ice cap is nearing summer and evaporating into gas that affects the polar clouds. (If any of our reader-astronomers catch a nice image, send it our way!)

From the ground, Mars will look like an orange star almost as bright as Sirius, the brightest star in the sky. The display may actually be best on Friday, Jan. 29, when Mars will rise alongside the first full moon of the year, directly opposite the sun.

Shame about the weather and the light pollution here in London! [Friday night update - the London skies miraculously cleared - extremely cold and clear, a spectacular full moon and, yes, the red planet. Well worth a look.] 

From the surface of Mars, we have an update on the stuck rover, Spirit. In spite of some recent success in the attempts to extricate it (progress of a few inches in the direction it was originally travelling), NASA has now designated the Rover as a "stationary science platform" - it will likely stay where it is for the rest of its working life, the duration of which will very much depend on its ability to combat and survive this Martian winter.

"There's a class of science we can do only with a stationary vehicle that we had put off during the years of driving," said Steve Squyres, a researcher at Cornell University and principal investigator for Spirit and Opportunity. "Degraded mobility does not mean the mission ends abruptly. Instead, it lets us transition to stationary science."

Meanwhile, Spirit's twin, Opportunity, has fallen very much out of the limelight during the stuck-in-the-sand saga, but it continues to trundle effectively about, conducting geological fieldwork. Most recently, it's been drilling away at a rock that would seem to represent the interior of the planet and something different from anything we've seen before.

And, on a completely different note, I have just cottoned on to the fact that this seems to be "Sand Week" on the geoblogosphere. Ron Schott pointed this out as part of his great series of "Deskcrop" posts of different sands - "We'll find out who knows their sands." See also his recent Outcrop post from Death Valley with great images of a sand storm and beautiful nascent dunes blowing across the road.

Sand - the paperback and a virtual book tour

 

OK, time for another commercial break - but with entertainment. The North American edition of the book is now out in paperback and, I have to say, very handsomely so, thanks to the production standards at the University of California Press. Last year I much enjoyed David Williams' idea of a virtual book tour for his wonderful book, Stories in Stone, so now, celebration of the paperback as the excuse, I'm about to embark on a similar venture.

The whole thing kicks off today with Brian Romans at Clastic Detritus (an appropriate place to start) where there will be a review and then, tomorrow, a Q&A session - I'll do my best to offset the time difference between London and California and be online for that as long as possible.

Then, for early next week, Callan Bentley's students have fired off a bunch of great questions that I will attempt to answer, followed by David Williams and Stories in Stone. On dates yet to be determined, the tour will visit Andrew Alden at About Geology and Geoff Manaugh at BLDGBLOG. 

A couple of things that I should point out - first, that, depending on how Amazon.com is searched, the paperback doesn't always show up very obviously - here's the link and the page at the University of California Press site. Second, because the book was published on opposite sides of the Atlantic by two completely different publishers and with two different subtitles, there is sometimes some confusion. The American edition is "The Never-Ending Story," a reference to Michael Ende's book and the imagery of a sand grain as a symbol of rebirth, and, at the same time the ubiquity, durability and timelessness of sand as a player in our planet's processes. This subtitle has, unfortunately, been misinterpreted on occasion (the book really isn't that long) and the UK publishers, Oxford University Press, preferred to change it to "A Journey Through Science and the Imagination." It has a different format and different feel - but it's the same book, and will be, itself, out in paperback in May.

The US paperback, of course, takes advantage of the reviews that have appeared since first publication to quote the particularly juicy bits on the back cover. And so, since this post is already a flagrantly shameless act of self-promotion, I'll reproduce the quotes here. I hope that readers will find the tour events themselves entertaining, and my sincere thanks to all of the hosts.

If you go down to the dunes tonight......

 

And if those dunes are in Israel's Negev Desert, then you might be in for quite a big surprise. We are constantly surprised by the discovery of new species on our planet - but then, on reflection, not surprised, given the diversity of life and the limits of our knowledge, the places we really don't know much about. However, we generally expect new species to be from the small and microscopic end of the spectrum of sizes, tiny critters that have successfully hidden themselves away until their chance discovery. We are surprised when something new and large turns up, and even more so when it turns out to having been living next door to us as opposed to in the depths of the ocean or a corner of a far-flung rainforest. So Cerbalus aravensis is something of a surprise. This gigantic spider has just been discovered inhabiting the Samar dunes in the Arava region north of the tip of the Gulf of Aqaba. This is not a spider you would think would be easily missed - its leg span is nearly 15 cm, 6 inches and it's the largest spider of its type in the Middle East. OK, it's nocturnal and spends its days in a burrow in the dune, the entrance cleverly disguised by a lifting door constructed out of glued-together grains of sand, but even so.....

The discovery was made by a team of scientists from the Department of Biology in the University of Haifa-Oranim (photo by Yael Olek, courtesy of the University of Haifa). One of the reasons that the team was studying this area of dunes is that it is recognised as a unique and important habitat that is under threat. The Samar dunes were never exactly a sea of sand - in the past they extended only over an area of seven square kilometres - but they now cover less than three. Agriculture, infrastructure shutting off the supply of sand, and, most destructively, mining of the high quality sand for construction purposes, have all conspired to dramatically shrink their extent, and there's little sign of this stopping. Yet, despite their limited and diminishing extent, and the recent disappearance of inhabitants such as the Sand Cat (Felis margarita) or the Rüppell's Fox (Vulpes rueppelli), the dunes remain a habitat for a remarkable diversity of life, mammals, snakes, birds, insects, plants - and previously unknown giant spiders. What else is there that we don't know about? As Uri Shanas, leader of the research team, remarks, "The new discovery shows how much we still have to investigate, and that there are likely to be many more species that are unknown to us. If we do not preserve the few habitats that remain for these species, they will become extinct before we can even discover them."

But the Samar dunes are a classic example of conflicts between preservation, commerce, and politics. Part of the problem historically has been the theft of sand (another example of seemingly unlikely illegal trafficking - but it's valuable stuff). The solution identified by the authorities has been to license sand mining over a third of the area of dunes - “If it’s available legally, there will be less motivation to steal it." This has, understandably, been challenged and, as far as I can tell, the controversy continues.

Meanwhile, we need to find out what else might be lurking in the dunes....   

[For reports on Cerbalus aravensis, see Wired Science, Science Daily, and similar news sites. See also useful discussions of the controversy and the inhabitants of the Samar dunes, and an article from Haaretz on sand commerce]  

Haiti - liquefaction

 Much has been written on the chaos and the tragedy of Haiti while I have been offline, but I thought it worthwhile highlighting a couple of excellent sources. Chris Rowan at Highly Allochthonous has put together a very helpful summary of Caribbean seismic activity and tectonics - highly recommended.

Last October, on the twentieth anniversary of the Loma Prieta earthquake in California, I wrote on the devastating role of liquefaction of unconsolidated sand during that event and other earthquakes. In Haiti, tragically, the effects are there to see again. Dave Petley, of Durham University, who writes the fascinating Dave's Landslide Blog,  has put together a series of posts using Google Earth high-resolution imagery to illustrate liquefaction-triggered damage. These can be found here, here, and here.

The high-resolution imagery made freely available through Google Earth is extraordinary - of vital use to the relief effort, and simply riveting for everyone else. Combined with the latest historical imagery facility, Google Earth now allows "before and after" viewing of this kind of event, as well as the general ability to observe geologic and landscape changes - I can see a high risk of becoming unduly obsessed with this, with a deleterious effect on time management.

I looked more closely at a couple of examples of liquefaction damage to harbour facilities that Dave had highlighted (and it's no wonder that the news reports the enormous problems associated with delivery of anything by sea). As is so often the case, large parts of harbours are built on manmade land created by artificial landfill, the perfect material  for liquefaction. In the image at the head of this post, the effects of sand movement - compaction and lateral spreading under liquefaction - can be clearly seen, long fissures and associated slumping (the image was clearly taken at low tide, but I would suspect that the sandy coloured material is not a beach, but artificial fill - it certainly wasn't there in images from previous years.

Dave points out a CNN video report from one of the harbour locations that he highlights. It's well-worth watching, in part for the material on which the reporter is initially walking - it looks like sand. And, in the imagery below, the sandy-coloured smears are clearly associated with the massive liquefaction-induced fractures, and I suspect that this is liquefied sand ejected from those fractures, just as I described for the Loma Prieta earthquake.

[Breaking news - tonight, February 2, on UK television, a progamme on the causes of the earthquake followed the first geologist on the ground and, standing at exactly the scene below, he picked up some white sand and described how it had been expelled from the fissures by liquefaction.]

 

And then, googling along the coast, away from urban devastation, I noticed the delta shown in the "before and after" images below. Over just a few years, there are dramatic changes to the entire shape of the delta and the architecture of its channels. Some of this was undoubtedly happening anyway, in part under the influence of expanding agriculture, but I couldn't help but be impressed by the now dramatically braided channel system, the two massive and dominant channels, and the amount of sediment sluicing through them, one branch creating a great sediment plume.

 

Are we seeing increased sediment charge from earthquake-induced landsliding in the interior? How much of the changes in channel architecture may have been the result of the earthquake? Clearly, I don't have the answers, but the imagery raises some fascinating questions.

Explanation of absence

A quick note to apologise for the extended blog silence. I returned to the UK last Friday night, preparing to set to work on several projects, blog posts - of course - amongst them. On Saturday I didn't feel great, Sunday much worse, and by Monday afternoon I was in hospital from where I have just returned. I was struck by a raging infection from nowhere. All very mysterious and all very disruptive. The NHS did extremely well with the priority - endless intravenous slugs of antibiotics - but failed to provide any kind of internet connection.

I'm determined - full of grit, even - that the sandglass will be flowing again shortly!

Dune cross-bedding in action

Ron Schott recently posted some spectacular outcrop photos of the Navajo Sandstone showing superb dune cross-bedding – aeolian processes at work 200 million years ago. He wrote that “Sure, I’m a hard rock geologist, buy who wouldn’t be moved by sedimentary structures as beautiful as these.” Well, naturally, I certainly was. Below is an example of Ron’s photos, more of which can also be found on his flickr pages.

These images were inspiration to look back at my experience of watching these features form, live action, nature red in tooth and claw. A couple of years ago, on a clear candidate for the trip of a lifetime, I was revelling in the fantastic landscapes of the Western Desert, in the far southwest corner of Egypt, and a very long way from anywhere. We were camped in the midst of the superb dune field shown at the top of this post (I say “camped” but I had long since given up on a tent, much preferring to simply put a sleeping bag on the sand and relish the desert nights and mornings). That morning, as can be seen in the photo, the wind began to stir the sand, first into ephemeral plumes blowing off the crests of the dunes, and then, as it gathered strength, the landscape became kinetic. The notes that I made evolved into the opening of the deserts chapter of my book:

When sand moves under a gathering desert wind, it seems to take on a life of its own, to become a different form of matter—like a gas, like liquid nitrogen spilling and spreading, following the ground surface. Spraying off the crest of a dune, shimmering in the light, veils of sand race and ripple, spread and vanish, their place continually taken by the next gossamer sheet, dancing, playing, celebrating. Are these jinns, the spirits of the desert? The sight is beautiful and hypnotizing in the evening sun, but if the wind gathers speed, beauty rapidly vanishes as the violence and menace of a sandstorm grows. Suddenly, it seems as if the entire mass of desert sand has sprung from the ground to hurtle with the wind. On the surface, everything is moving, even the largest grains, rolling, tumbling, kicking smaller grains into the rushing current. The sky disappears, and the howl of the wind seems amplified by its cargo of sand. The air is filled with flying sand, unbreathable.

Suddenly, the entire crests of the dunes began avalanching down the steep slip faces, and, in somewhat challenging conditions for photography, I tried to record the way in which successive avalanches poured off the crests, the whole sequence of instability taking on the appearance of a curtain being drawn across the dune face. I’ve reproduced two successive photos below in an attempt to illustrate this. Both images are “anchored” at the same point on the lower left, and, if you trace the number of individual slides from left to right, you’ll see the change from one photo to the next. The curtain of avalanches continued to rush across the face of the dune – but I needed to put my camera away, out of the cloud of blowing dust and sand.

I’ve written before about Ralph Bagnold - “The man who figured out how deserts work”. He was, first and foremost, a scientist and an engineer, but occasionally he allowed his lyrical side to show through in his writing. Standing there that morning, transfixed by the drama unfolding in front of me, I was reminded of Bagnold’s description of exactly what I was watching:

Up above the great fine-grained crests of the dunes were on the move. Cornices dissolved as we looked, swaying along the curving surfaces in heavy dark folds, as if the mane of some huge animal was being ruffled and reset in a new direction by the gale.

This is exactly what was happening 200 million years ago in Ron Schott’s Navajo Sandstones: successive avalanches of sand carving away at the pre-existing surfaces of the dunes, piling up new layers at a different angle to the older ones, cross-bedding in action.

Such is the behaviour of granular materials – on all scales. You can replicate cross-bedding formation in the kitchen – as I did, and described in earlier posts, together with the role of the angle of repose. The photo of my experiment below is intentionally scale-less.

 

The Navajo Sandstone is justifiably famous for its dramatic displays of ancient dunes and cross-bedding. But I should point out that, in the UK, we have some quite dramatic examples too. For a long time during the Permian and Triassic, around 270 million years ago, much of the UK was a desert. The dunes are well-preserved in the photo below of the old quarry at Ballochmyle in southwest Scotland.

The Mauchline sandstone, as it was locally known, was for a long time a valued building stone, not only for much of Scotland, but also for export to the US. The peak of production at the quarry was around the turn of the nineteenth century, with dedicated railway transport and more than two hundred people employed. By the early years of the twentieth century brick had replaced stone as the construction material of choice, and the quarries closed by the 1950s. We may have great outcrops of aeolian cross-bedding in the UK, but, sadly, the Ballochmyle quarry is no longer one of them – it’s now filled with household refuse.

[The quarry photo comes from a great resource for UK geology that I have only just discovered. In the past, the British Geological Survey was a poor relation of its US counterpart in terms of web-based public domain resources. But now, their OpenGeoscience site contains, amongst other treasures, a collection of thousands of images – including comprehensive aerial photographic coverage of the recent floods that I described last month.]

Never leave home without it: The Pocket-Size Sand Grain Sizing Folder

Concerned about the origin of the sand covering your car after the kids have borrowed it? Or where that cowboy builder is getting his supplies from? Curious about why the sands on one beach make much better sandcastles than those of the next one along the coast? Or why the sand traps/bunkers on one golf course are more deadly than another? Or, then again, maybe you’re a geologist. For you, the handy-dandy Pocket-Size Sand Grain Sizing Folder could be the solution. Is available from the Geological Society of America or directly from SGE* at Kent State University for a bargain price, and I have recently become the proud owner of one. It’s a very visual reference for several ways of describing sand, first of all, of course, size. Size is the only character that defines a granular material as sand, and the size categories (from “very fine” to “ very coarse,” much like sandpaper grades) progress in multiples of two – 1/16 to 1/8 mm, 1/8 to 1/4 mm and so on up to 1.0 to 2.00 mm – simply because nature works in multiples rather than linearly (think of a square versus a line, a cube versus a square). Anything finer than very fine sand is silt or mud, and things coarser than very coarse sand are granules, pebbles, cobbles, and boulders. This scheme has a real physical basis: sand-sized materials behave very differently from anything bigger or smaller – and that behaviour is often quite bizarre (as I’ve described on several occasions – see, for example, the formation of convection structures). The Pocket-Size Sand Grain Sizing Folder provides a direct reference to sand size categories by including small samples of real sand (see the illustration at the top of this post). 

But the folder does more than give a reference for size – it provides graphics of poorly-sorted and well-sorted sands in three different size categories, a key character of how uniform or otherwise is the range of size of the grains in a particular sample. Sorting provides clues as to the transportation biography of a sand – wind-blown sand will contain a much smaller range of grain sizes (i.e., better-sorted) than a river or shoreline sand simply because the capacity of the wind to transport larger grains is much lower than that of water. But it’s not that simple: sand transport is a complex process that continues to occupy researchers in fluid dynamics as well as sedimentology. The two sands below are from, on the left, a beach and, on the right, dunes just a few meters away. Not only are they different in size (in this case, oddly, the dune sand is coarser than that of the beach), but the beach sand is more poorly-sorted than that in the dunes. 

 

But there’s another clear and dramatic difference between these two sands: the shape of the grains. The dune sand grains are both more rounded and smoother than those from the beach. Here, the Pocket-Size Sand Grain Sizing Folder is again helpful: it provides a visual reference and a scale for grain roundness and sphericity (the central panel in the image at the top). Roundness roughly reflects how angular and sharp the edges of the grain are, sphericity how closely its shape approximates that of a sphere. All of these characters, size, sorting, roundness, and sphericity, are characters that serve to distinguish one sand grain, and one family of sand grains, from another – regardless of what they’re made of. And these distinctions are testaments to the varied origins and biographies of those sands . But describing accurately the shape of something as irregular as a typical sand grain is a challenge that continues to vex geologists – after all, how would you measure the shape of one of those knobbly tomatoes or a banana? In part, the way you approach the problem is determined by what you want to get out of it, and so there a multiple different methodologies. For example, another esoteric measure of grain shape is rollability – how easily the grain tips over. And the closer we look, the more complex – but fascinating – things become. Below is the face of a single sand grain half a millimeter across; the right hand image is the surface of the grain as seen through a scanning electron microscope. Magnified 1500 times its original size, an entire miniature landscape opens up to us.

In some ways, the character of the face of a sand grain is similar to human physiognomy – it contains all sorts of biographical clues. And to push this analogy a little further, there’s a similar “nature versus nurture”  question: which surface characters of a sand grain reflect its origins (weathered out from a rotting granite versus an old sandstone, for example) and which its subsequent life story and journeys? 

The extraordinary ways in which the shape and character of a sand grain can tell us about its history and help reconstruct episodes and environments in the chapters of our planet’s history are fodder for all kinds of future blog posts. Suffice it to say, for now, that these things are vital for the geological sciences. And the shapes of sand grains are vital to our daily lives – as an admittedly non-vital example, the shapes (and the sorting) of different beach sands contribute fundamentally to whether or not they make for good sandcastles. Today’s methods for measuring sand grain shape become progressively more sophisticated. Take an image of the outline of a sand grain, find the centre, and measure the radius as it changes around the shape; this generates a mathematical curve that can be subjected to Fourier analysis – the mathematical construction of a complex wave form from the combination of a series of simple ones (I’m just about reaching the limits of my mathematical comprehension here). The result uniquely describes the shape and can be used to compare shapes of different grains. This method has been in use for some time, but continues to produce surprises – for example, workers at Scripps Institution of Oceanography have recently described how, regardless of the origins of their samples, grain shapes conform to a common power law, that seemingly ever-present way in which nature works (see, for example, earlier posts here or here). This means that grain shapes can be reproduced mathematically that precisely mimic natural ones, hugely useful for modelling the mysteries of packing, the ways in which sand grains fit together depending on their shape; this may seem esoteric, but it’s of fundamental importance for sand as a construction material, for understanding the porosities of sandstones as reservoirs for water and oil and gas – not to mention the behaviours of sand traps on the golf course.

The analysis of sand grain surfaces and shapes then moves into three dimensions, both via Fourier analysis and through other techniques; meticulous measurement of the way in which nitrogen gas is adsorbed onto the surfaces of sand grains can provide very precise information on three-dimensional shape and surface texture. These kinds of data can be invaluable not only in the everyday uses of sand, but also in criminal forensics.

All this is by now, of course, a long way from my simple  Pocket-Size Sand Grain Sizing Folder, but the principles are the same. It’s extraordinary the stories that sand grains have to tell. I will leave you with an image from what has now become a classic, W.H. Mahaney’s 2002 Atlas of Sand Grain Surface Textures and Applications: 

* SGE, Sigma Gamma Epsilon, is the US National Honor Society for the Earth Sciences; the Kent State chapter operate the sales of the sand-size folders as a long-standing and major fund-raising project.

[The image of the individual sand grain is courtesy of Dave Krinsley, who inaugurated the use of scanning electron microscopy to decipher the surface character of sand grains more than 35 years ago. For a basic discussion of grain sizes and shapes, see Sand and Sandstone, the Potter, Pettijohn, and Siever bible.]

La Théorie du Grain de Sable

“You’ve never heard speak of The Theory of the Grain of Sand? The little nothing, the detail that can be enough to change everything…”

With a title like that, this was a book I had to have. In France, the bande dessinée or “BD,” the graphic novel, is an art form and hugely popular. All bookshops have shelf after shelf of BDs and the variety is spectacular, from the simple comics for kids to complex and sophisticated works for adults; more than 30 million BDs are sold every year in France. I had discovered the first volume of La Théorie du Grain de Sable a couple of years ago, and was frustrated to find that I had to wait for the second book; this Christmas, there it was.

The story takes place in a kind of parallel steampunk universe, and is part of a thematic series titled Les Cités Obscures, translated as “The Fantastic Cities” or, more straightforwardly, “The Obscure Cities.” The authors, François Schuiten and Benoît Peeters, have created a “counter-earth” made up of individual city-states that seem to be twinned in some way with their “real” equivalents – objects and people are occasionally translated between them. La Théorie is set in the fantastic city of “Brüsel” in some fantastic year 784; aspects of technology indicate that the time is in  the future, but much of the architecture, faithfully and dramatically drawn, is of the classic Brussels, and many of the styles of clothing are distinctly retro. It’s an atmosphere characteristic of the Cités Obscures project, and following the very French philosophical approach of “it’s all very well in fact, but how does it work in theory?” the project has been the subject of detailed literary analysis. One can find discussions on the internet of “the city as a political and aesthetic model” and “obscurité as an ontological model.”

But what of the story? Strange events start happening in Brüsel, in some way associated with the visit, and untimely death, of a stranger from a strange land. In one man’s apartment, rocks begin appearing out of nowhere, each weighing precisely 6793 grams (a prime number…..); their accumulation eventually reaches the critical mass of causing major structural problems with the building and, not surprisingly, a profound deterioration in the man’s relations with his neighbours. Not far away, a chef begins to levitate involuntarily, the condition progressively worsening as his stable altitude becomes further and further from the ground; he is forced to close his restaurant because he is frightening his clientele.

But most bizarrely, and of greatest interest, is the plight of a young mother who finds her apartment invaded, at first by a trickle, and then by a deluge, of sand. Sand pours from under the doors and cascades out the cupboards, accumulating as dunes in every room. While this drives the poor woman to despair (her attempts to dispose of it by surreptitiously carrying out bucketsful being completely futile), it delights her two young kids. They can now build sandcastles in their living room. In the graphic extracts below, as one kid empties out the container, he declares “success! It’s only necessary to add a little water…” and “they hold together well, you know – come and see, Mom!” (that’s Mom in the background, taking another pill).

Friends are invited  over for sandcastle parties - “this one’s going to be the most beautiful!” and the girl comments that it’s a shame they don’t have any shells.

 

But eventually, the fun, at least as it was for the kids, is over. Sand completely fills the apartment as the poor woman cries for help, pours out of the windows, and starts to bury the city.

 

In the foreground of the graphic on the right is Mary von Rathen, who is a specialist in investigating bizarre events. She has arrived from another city in order to try to solve the strange phenomena that threaten Brüsel. Mary was known, apparently from earlier novels as l’enfant penchée, “the leaning child” – I have yet to figure out why. It is Mary who describes “The Theory of the Grain of Sand” and ultimately identifies the cause of the problems and the solution – linked, of course, to the mysterious stranger. The story is far more complex than I have outlined here and I won’t spoil it. It is, in every sense, fantastic, and the graphics are superb. And, not surprisingly, I derive great pleasure from every discovery of another example of how a grain of sand can penetrate our imaginations – and this one’s even good for my French!