Through The Sandglass

Reposing differently on Mars

Sand, Mars, and a challenge to conventional wisdom. What better ingredients for a post could I wish for?

The two images above show sedimentary fan deposits, the great  - yes, fan-shaped – aprons of detritus that accumulate at the foot of a gully, driven by gravity, often, on earth at least, assisted by periodic torrents of water. Water is an interesting factor: on Earth these things are often called “alluvial fans” because the occasional flood clearly plays a role.

These images are an opportunity for a quiz, since one is from Earth and the other is from Mars – which is which? Sorry, but I’ll maintain the suspense for a while. Are the fans on Mars alluvial – is water involved? The debate about the role of water in Martian surface processes continues, and it’s fascinating and the evidence for,against, ambiguous, is diverse. One of the lines of reasoning involves the slopes of fan deposits – they can be characterised by lower angles than expected and this is cited as a result of the lubricating effect of water. But this makes one critical assumption: that the slope of a deposit of granular materials (the angle of repose) is not affected by the low gravity of Mars – the angle of repose is independent of gravity. But is this assumption correct? Oddly enough, this question had not been seriously addressed until Maarten Kleinhans of Utrecht University together with Sebastiaan de Vet of the Institute for Biodiversity and Ecosystem Dynamics (IBED) at the UvA and colleagues from Delft University of Technology decided to do so. How? Well, as the University press release describes, they took a plane:

The research team used a parabolic flight campaign to mimic Mars’s lower gravity and test the effect on angles of repose of different materials. As the plane followed its roller coaster style path, slowly rotating cylinders containing different materials experienced one tenth of Earth's gravity, Martian gravity and the Earth's normal pull.

And here, from their paper in the Journal of Geophysical Research, is the gravity-reducing plane.

 
But, before we look at what they found, let’s back up for a minute and remind ourselves about angle of repose. In its simplest sense it’s the slope that sand, or any granular material, naturally settles at after it has been poured. It varies substantially with the nature of the material – grain size and shape and so on. The paper included this helpful illustration of “A pile of rounded gravel at the angle of repose, built by Gijsbert F. Kleinhans.”

Because it’s important in many contexts, I have written several posts on the angle of repose, for example in kitchen physics, and “From Bogart to Bugs,” And it’s one of many principles of physics that can be observed simply by watching the flow of sand in this blog’s icon, the sandglass. But the sandglass, simple though it may appear, illustrates the complexity of many things, among them the angle of repose. For there is not one simple angle of repose for a given material – there is a static one and a dynamic one. Essentially, the static angle of repose is demonstrated when a pile of grains is at rest, but, once they start avalanching down a slope, the constant angle of the avalanche is different, and that’s the dynamic angle of repose, always lower than the static.

There are different ways of studying all this (should you be inclined – and many people are), but a classic is the rotating cylinder. This is basically like watching clothes in the drier – a transparent cylinder is partially filled with granular material and rotated – the sand, or whatever stuff you chose, cascades down-slope constantly at it’s dynamic angle of repose. When it comes to rest, it does so at its static angle. This is exactly the equipment that the Dutch researchers took up with them in their gravity-reducing plane: nine cylinders half-filled with sand, gravel, glass beads, some in air, some in water, their behaviours captured by HD video cameras:

All kinds of clever corrections for the noise and accelerations of the aircraft itself were applied. Each stomach-churning parabola allowed for around 20 seconds of experiment at gravities of down to one tenth the normal earthly value – the gravity on Mars is just over a third of Earth’s.

As the authors write in their paper, “Our main result is surprising.” They found that, with decreasing gravity, the static angle typically increases by around 5 degrees, whereas the dynamic angle decreases by about 10 degrees. And this is true of all the materials and regardless of whether they were in air or water – the angle of repose is not independent of gravity. The difference between the two angles is critical to the natural behaviours of granular materials, and in these experiments it increased by roughly an order of magnitude. Why is this important? If the static angle is higher, then a slope can build more steeply, but, once stability is lost, then avalanches cascade down the slope at the dynamic angle – if this is low, then the avalanches keep going and involve more material.

So, bigger avalanches, lower slopes on Mars are possible without the lubricating effect of water. And, as the authors point out, this gravity dependency of the angle of repose has implications for a wide variety of phenomena on Mars and elsewhere.

Ah yes, the answer to the quiz: it was great fun juxtaposing these images (well, to me at least) because of their remarkable similarities. The image on the left is of gullies and fans in a severely eroded 100 kilometer impact crater in the southern polar region of Mars (courtesy NASA/JPL/University of Arizona). On the right is a Digital Elevation Model (DEM) image of gullies and fans on Svalbard (a.k.a. Spitsbergen) from the Europlanet HRSC-AX flight campaign. The laws of physics are compellingly universal.

 

[Many thanks to Brian Romans of Clastic Detritus for catching this paper for me. Paper citation: Kleinhans, M. G., H. Markies, S. J. de Vet, A. C. in 't Veld, and F. N. Postema (2011), Static and dynamic angles of repose in loose granular materials under reduced gravity, J. Geophys. Res., 116, E11004, doi:10.1029/2011JE003865.]

Flux

 
Aral Sea shrinks, central Asia

The Aral Sea, located in Kazakhstan and Uzbekistan in central Asia. Left: June 4, 1977. Center left: September 17, 1989. Center right: May 27, 2006. Right: June 3, 2009. Once one of the largest inland bodies of salty water in the world and the second largest sea in Asia — 70,000 square kilometers or 27,000 square miles in area — the Aral Sea has shrunk dramatically over the last 30 years. One of the main reasons is crop irrigation: water has been drawn off from the rivers that kept the Aral Sea filled. As the sea has shrunk, the local climate has become harsher, there have been contaminated dust storms, and drinking water and the local fishing industry have been lost. By the late 2000s, the Aral Sea had lost four fifths of its water volume.

Images taken by the Multispectral Scanner onboard Landsat 1, the Thematic Mapper sensor onboard Landsat 5, and the Enhanced Thematic Mapper Plus onboard Landsat 7. Source: USGS Landsat Missions Gallery, "The Vanishing Aral Sea," U.S. Department of the Interior / U.S. Geological Survey and Encyclopaedia Britannica Online.

I just came across another extraordinary internet resource courtesy of NASA (whose captions and credits are quoted throughout). Titled “State of Flux – Images of Change,” it currently contains close to two hundred images of changes to the surface of our planet over the last few decades – it makes for mesmerising browsing. It comes under “climate.nasa.gov” but it’s by no means only about climate change – it chronicles other natural processes together with the – often depressing – footprints of our species. I found the site through a Scientific American blog piece titled “Views from Space show a Fragile Earth.” I must admit that I find this a strange title, an example of the emotional use of the word “fragile". This planet has been around, perfectly successfully and robustly, for 4.5 billion years – fragile it ain’t. The fragility of our own precarious and short-lived perch on the planet is another thing – and, in reality, what is being referred to by the adjective. But I am not setting up my soap-box here – the point is to celebrate the technology, and the access to it, that NASA offers. And yes, celebrate – we may, as many of these images provocatively show, be screwing around with the current nano-frame of the planet’s biopic, but at least we can’t hide that fact.

The following images are simply a personal selection after an initial browse, starting with the classic at the head of this post; further comment is hardly necessary.

 

River changes, China

The Yellow River Delta in China. Left: 2001. Right: 2009. The Yellow River is the second-longest river in China, and the sixth-longest in the world. It has been the cradle of Chinese civilization; but frequent devastating floods have also earned it the name of "China's Sorrow." Historical maps tell us that the river has undergone many dramatic changes in its course. Currently, the Yellow River ends in the Bohai Sea, yet its eastern terminus continues to oscillate from points north and south of the Shandong Peninsula. These images show the changes.

Images taken by NASA's Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument. Caption adapted from the ASTER gallery. Courtesy of NASA/GSFC/METI/ERSDAC/JAROS and the U.S./Japan ASTER Science Team.

 Agricultural growth, Egypt

Dakhla Oasis, Egypt. Left: January 4, 1986. Right: January 14, 2010. Dakhla Oasis lies 300 kilometers (190 miles) west of the Nile. It is surrounded by the driest of desert landscapes, but beneath it lies the southern edge of the Post Nubian Aquifer. Use of water drawn from deep wells in the aquifer has increased tenfold since 1960, with a corresponding growth in agriculture. But some studies suggest that the planned rate of extraction is unsustainable and will lead to local depressions in the water table, making the precious liquid more and more expensive to access.

Source: United Nations Environment Programme (UNEP). From Africa Water Atlas (2010); Division of Early Warning and Assessment (DEWA), UNEP, Nairobi, Kenya.

 Delta growth, Kenya

The Omo Delta, at the north end of Lake Turkana, a lake now located mainly in Kenya. Left: February 1, 1973. Right: January 24, 2005 to February 12, 2006. In 1973, the delta was contained entirely within the boundaries of Ethiopia. By 2005-2006, the southernmost point of the delta had moved roughly 12 kilometers (7 miles) to the south, and had crossed the Ethiopia-Kenya border. Reduced lake levels — from less rain, more diverted upstream water, and increased evaporation due to higher temperatures — are believed to be the primary cause, with an increase in sediment from agricultural activities also contributing. The expanded delta has provided new land for 20,000 Dassanech people, the area?s traditional inhabitants. But severe flooding in 2006 killed 100 of them and destroyed houses, crops and infrastructure.

Source: United Nations Environment Programme (UNEP). From Kenya Atlas of our Changing Environment (2009); Division of Early Warning and Assessment (DEWA), UNEP, Nairobi, Kenya.

 Lake shrinkage, Egypt

Toshka, Egypt. Left: September 13, 1984 to September 29, 1987. Center: August 23 to September 1, 2000. Right: March 21 to 28, 2010. In the mid-1990s, excess water was channeled from the Lake Nasser reservoir on the Nile River to the Toshka Depression in the Western Desert, creating a series of lakes. This "New Valley Project" was to relieve overcrowding within the Nile Valley and boost the economy. Despite soil poorly suited to irrigation, the area produced grapes, cantaloupes, tomatoes, cucumbers, citrus fruits and wheat. But Lake Nasser water levels fell after 1998 and flow to Toshka ceased in 2001. At the current rate of decline, the new lakes will be lost to evaporation within the next few years.

Source: United Nations Environment Programme (UNEP). From Africa Atlas of our Changing Environment (2008); Division of Early Warning and Assessment (DEWA) UNEP, Nairobi, Kenya.

Mining growth, Chile

The Atacama Desert, Chile. Left: November 23, 1987. Right: June 25, 2009. Population has doubled here over the past two decades due to explosive tourist development in the 1990s and a mining boom in the 1980s, when companies began to extract lithium and other minerals from the Atacama Salt Flats. Today the mining, tourism, domestic and agricultural sectors compete for the region's resources, and the main source of conflict is access to water. These images show the growth of mining operations from their beginning (white rectangle at lower right of the 1987 image) to a more recent level (purple and while rectangles in the 2009 image).

Source: United Nations Environment Programme (UNEP). From Latin America and the Caribbean Atlas of our Changing Environment (2010).

 Deforestation, Niger

Left: January 12, 1976. Right: February 2, 2007. Baban Rafi Forest is the most significant area of woodland in the Maradi Department of Niger, a west African country on the southern edge of the Sahara Desert. Located at the southern extreme of the Sahel, Baban Rafi has areas of both savannah and Sahelian vegetation. These pictures show the loss of a significant fraction of the natural landscape (darker green areas) of the forest to agriculture. Population in this region quadrupled during the 40 years leading up to the 2007 image, and intense demand for agricultural land has led to near-continuous use, with shortened or no fallow period to recover fertility. The remaining woodlands are overly exploited for fuel wood and non-wood forest products.

Source: United Nations Environment Programme (UNEP). From Africa Atlas of our Changing Environment (2008); Division of Early Warning and Assessment (DEWA), UNEP, Nairobi, Kenya.

And, finally, just a little local colour, since this is where I am:

 Urban growth, Indonesia

Jakarta, Indonesia. Left: 1976, with a population of six million. Middle: 1989, with nine million inhabitants. Right: 2004, with 13 million inhabitants. Jakarta was the last Hindu kingdom of West Java when the Portugese arrived in 1522. They were driven out 5 years later by Muslim saint and leader Sunan Gunungjati, who renamed the city Jayakarta. In the 17th century the Dutch captured the city, fortified and walled it, and renamed it Batavia. After World War II, Dutch colonial power came to an end when Soekarno declared the Republic of Indonesia. This time series of images shows the growth of the city over the past few decades; vegetation is rendered in red and urban areas shown in blue-grey.

1976 image acquired by the Landsat MSS scanner. 1989 image taken by the Landsat Thematic Mapper. 2004 picture captured by ASTER. Credit: NASA/GSFC/METI/ERSDAC/JAROS and the U.S./Japan ASTER Science Team. Caption adapted from the ASTER gallery.

They wept like anything to see such quantities of sand

 
The owners of otherwise delightful beachfront homes on the Oregon Coast near Waldport, Oregon, must feel like responding as the Walrus and the Carpenter did – except that their situation is much, much, more serious.

Many thanks to Howard Allen for spotting this recent report by Dan McShane on his “Reading the Washington Landscape” blog. It shows homes literally half-buried in sand and such disastrous events were reported last year by KCBY in Coos Bend, from where the images above were taken. A winter storm had “left sand piled up to the roof level of some homes in Waldport.” But can we disengage from the human component of the equation and observe this simply as another example of naturally dynamic coastal geology? Probably not.

Inevitably on this blog, I have commented a number of times on issues of coastal processes, our attempts (generally futile) to “manage” them, and on the feedback between nature and human activities; “nourish or retreat?” was a relatively recent example, “Coastal change and saving sand - the state of the art” looked at meticulous work on this topic by the USGS and others, then there was the impact of Hurricane Irene, and a discussion of sediment budgets (and I have omitted my series of fulminations on the lunatic schemes for the Gulf Coast following the Macondo catastrophe). But I was reminded also of the publication of Orrin Pilkey’s book on beaches in August last year, when I wrote as follows:

I have referred several times in the past to Orrin H. Pilkey, James B. Duke Professor Emeritus of Geology at Duke  University. Now, together with colleagues from the US and Northern Ireland, he has published what promises to be an informative, entertaining, and provocative read - The World's Beaches: A Global Guide to the Science of the Shoreline. I haven't, of course, got my hands on a copy yet, but a review in the New York Times simply confirms that anything by Pilkey is required reading. The review is titled "Shorelines, Sandy or Otherwise, That May Not Last." The conclusion echoes the issue that I posted on a couple of months ago:

But, the authors conclude, unless society chooses beaches over buildings the result will be a world in which parks like the National Seashores retain natural beaches, but beach resorts elsewhere are “heavily walled and beachless.” Rising seas will make sand-pumping operations “untenable,” they predict, and tourists will amuse themselves by “promenading on top of a seawall” — already the principal activity in too many coastal resorts.
If they are right, by then the beaches this book describes will be a nostalgic memory.

The book is published by the University of California Press, to whom I will ever be grateful for publishing mine, and the New York Times review is by Cornelia Dean, whose own book, "Against the Tide: the Battle for America's Beaches," also falls into the required reading category.

Now the hazards of owning a beachfront home in Waldport Oregon remind us dramatically that it’s not simply shifting shorelines that are impacted by human activity (and, regardless, represent an entirely natural threat). Invariably, when beachfronts are developed, the first things to go are the dunes (after all, they obstruct the view). But dunes are an integral and vital part of the shoreline system – remove them and that system is destabilised. Once destabilised, it is then vulnerable (as are properties) to windblown movement of sand on a massive scale.

Being, as ever, curious, I went online to try to find more on coastal dynamics at Waldport. I’m sure there are more recent studies, but this piece of work from 1975 by the Oregon Department of Geology and Mineral Industries proved fascinating and more than sufficient: "Recent Shoreline Changes of the Alsea Sandspit, Lincoln County, Oregon." Written by James Stembridge of the Department of Geography at the University of Oregon, it provides some historic portents.  

The buried houses are built on a shape-shifting promontory of sand, the Alsea Sandspit, and here is a photo of it from 1975 (compare with the Google Earth images below):

 
And here, from that publication, is a compelling map of changes to the spit over the period from 1939 to 1975:

I have extracted some informative passages from the publication (remember, this was 37 years ago – before anything like the scale of today’s development):

Erosion of coastal sandspits has been a recognized hazard in Oregon since the demise of the resort community of Bayocean near Tillamook, which was slowly eliminated by the sea beginning in the late 1920's. Currently, the sandspit at Siletz Bay is undergoing severe erosion which is critically endangering structures along a three-mile beach front. Partially as a result of these experiences with eroding sandspits, some planning agencies, such as the Oregon Coastal Conservation and Development Commission, have considered limiting the construction of housing units on sandspits.

This study is a preliminary analysis of a third Oregon spit, the Alsea near Waldport, with respect to recent shoreline changes, human modifications, and potential impact on current and future settlement.

Unlike the Tillamook and Si letz spits, the Alsea sandspit is presently accreting at a rate as great as 10 feet per year at its southwest margin. Erosion at a rate of as much as 2 feet per year is occurring on the bay side of the spit, however, as well as along the northwestern margins of the spit, where the underlying terrace of semi-consolidated Pleistocene dune deposits is exposed to ocean wave action.

...... This main foredune is at least partially bulldozed into shape and rests at a position of up to 100 feet inland of its 1939 location. It is well stabilized with European beach grass (Ammophila arenaria), except where breached for home sites and by trails from the residential area to the surf zone. Its present height is approximately 35 feet above mean high tide level, increasing at a rate of about 0.5 feet yearly as sand accumulates in the vegetation. The extreme high tide line has moved as much as 300 feet seaward since 1939 (Figure 5). Part of this general accretion is the building of what appears to be a new foredune as much as 300 feet seaward of the 1939 foredune.... Blowing sand will continue to be a problem where the foredune has been breached and where there are expanses of unvegetated sand.

Sandspits have been described as oscillatory in that they may experience irregular cycles of erosion and deposition. If the spit at Alsea is currently prograding, the situation could reverse at any time.

Note the last two paragraphs – it seems unnecessary to say anything more. The coast is a good teacher, we are just lousy learners.

Sunday sandy satellite scenes

I discovered that DigitalGlobe have recently held their contest for the best satellite image and GeoEye have issued their 2012 calendar images. Both are stunning galleries of our planet’s surface, natural landscapes and manmade features, but my eye was, of course, taken by the diversity of sand’s role in many of them.

The GeoEye image above is of Qatar:

This image of South Qatar shows how the ebb and flow of the tide can create some unusual formations. Here, water and sand conjure up the shape and color of a tree as the tide swirls into the Persian Gulf. Qatar, an Arab Emirate in the Middle East, is one of the region's wealthiest states due to its vast oil and natural gas resources.

And here is their image of the Algerian Sahara:

 

The Eastern Algerian portion of the Sahara is an otherworldly place, a region of great diversity with endless stretches of sand dunes and rocky platforms that can reach more than 2,000 meters. The Tassili n'Ajjer "Plateau of the Rivers" National Park is a vast plateau in southeast Algeria at the borders of Libya, Niger, and Mali, covering 72,000 square kilometers.

Then here is one of the finalists from DigitalGlobe, stunning channels of the  Betsiboka River as it flows into Bombetoka Bay, Madagascar:

 

Bombetoka Bay, Madagascar-May 2, 2011: This is a satellite image of Bombetoka Bay, a bay on the northwestern coast of Madagascar near the city of Mahajanga, where the Betsiboka River flows into the Mozambique Channel. (credit: DigitalGlobe)

And this image from New Zealand was DigitalGlobe’s winner:

 

Rakaia River, New Zealand-March 28, 2011: This is a natural color satellite image of the Rakaia River in the Canterbury Plains in New Zealand's South Island. (credit: DigitalGlobe) <www.digitalglobe.com DigitalGlobe

 

[P.S. Difficult though it is for me to believe, this is my 351st post!]

Sunday Sand Scene

OK, the Paris-Dakar rally is controversial, but this is simply such a spectacular image.

 

[Peru, photo Reuters/Philippe Desmazes]

Sunday Sand: Wrangellia

 
A hundred million years ago, over the western ocean horizon, loomed yet another impending tectonic disaster. A gigantic plateau of volcanic rock was lurching its way eastwards towards an inevitable collision with North America, the oceanic plate that carried it being consumed beneath the continent. The plateau was far too massive to be digested, instead winding up accreted – welded, glued, uplifted – to an ever-expanding continent to form, amongst other things, the backbone of what is today Vancouver Island.

This collision and continent-building event took place along the entire stretch of western Canada and Alaska, one chapter in the saga of tectonic chaos that would continue along the whole margin of North America to the present day. It wasn’t simply one plateau of volcanic rocks that blundered into its final resting place, but a complex of oceanic bits and pieces, deep marine sediments, cherts, limestones, geo-flotsam and geo-jetsam, different terranes that have come to be grouped together under the name Wrangellia, after some fine examples in Alaska’s Wrangell Mountains:

 

In the vicinity of Vancouver Island, the Wrangellia terrane was uplifted and rapidly eroded, sand and mud pouring off the new mountains to form deltas and marine deposits, shallow and deep, accumulating to a thickness of five kilometers. This pile of sediments is referred to as the Nanaimo Group, and underlies much of the south-eastern coast of Vancouver Island, where a colleague of mine is lucky enough to live (when he’s not being a colleague of mine and working in Indonesia).

 
He looks out eastwards over the deliciously named Salish Sea to the hills of Lasqueti Island and the mainland, across a beach that is a broad bench, strewn with cobbles, pebbles, and gravel – between which can be found today’s Sunday Sand.

 
And, as usual, this sand consists of local ingredients, detritus of Wrangellia – and the detritus of the detritus of Wrangellia. It’s a young, angular, coarse sand, the grains not yet well-travelled – the photos are of the sample sieved to collect only the sand-sized fraction. The grains are of grey and greenish volcanic rock, originally erupted on to the floor of the ancestral Pacific Ocean, 200 million years ago, deep-sea sediments, red chert fragments, bits of limestone, the odd quartz grain, the occasional piece of broken shell.

The story of Wrangellia, recounted by this sand, was but an early episode in an ongoing series of events in which successive wandering foreign tectonic chunks accreted themselves to Western Canada – the Pacific Rim Terrane, the Crescent Terrane. And, as this cross-section shows, it’s still going on today. Out in the ocean, far to the west of Vancouver Island, lies the true edge of North America, sediments and oceanic material scraped off the top of the subducting Juan de Fuca Plate, in the fullness of time to make their contribution to the territorial expansion of Vancouver Island.

 

[Illustrations from Steven Earle’s The Geology of British Columbia and Vancouver Island – if you, like me, can’t get to the original, try the Google “quick view” version ; for more on Wrangellia, see this University of British Columbia site; and thanks, Brett, for the sand!]

A selection, a reflection, and a wish for 2012

It’s that time of the year when I, for one, am grateful that the endless reflections in the media on the previous twelve months must come to an end – the events and non-events, the ups and downs, the highs and lows, the progress or otherwise, the marriages and divorces of mediocre “celebrities,” the genuinely positive and the utterly banal. There will be one list here, but of a different nature.

It’s impossible to avoid some form of reflection as we approach the New Year, and, out of curiosity, I have looked at the activity on this blog over the last month, the most recent few thousand visits (from, pleasingly, 117 different countries), and tried to discern why the top ten and the bottom ten posts were ranked that way. I gave up (other than appreciating that critters are always popular). But, since one of the (many) reasons that anyone tries to keep up an entertaining blog is some kind of satisfaction, I reflected on which of the top ten – and, even more interestingly – which of the bottom ten posts I would select as ones that I remain in one way or another pleased with.

Selecting from the top ten was easy – I derive considerable pleasure from the fact that the piece on Gaudi and the sandstones of Barcelona, although written nearly two years ago, seems to have an enduring popularity. As for the bottom ten, this was more of a challenge; some of them are trivial and their lowly rankings quite understandable. But I find it vaguely depressing that the post on last year’s Earth Science Week and Earth Science Literacy attracted 0.02% of the visits.  

The headline statement from the Earth Science Literacy initiative is as follows:

An Earth-science-literate public, informed by current and accurate scientific understanding of Earth, is critical to the promotion of good stewardship, sound policy, and international cooperation. Earth science education is important for individuals of all ages, backgrounds, and nationalities.

And here (now for the third time on this blog) are the “Big Ideas” from that program:

Big Idea 1. Earth scientists use repeatable observations and testable ideas to understand and explain our planet.

Big Idea 2. Earth is 4.6 billion years old.

Big Idea 3. Earth is a complex system of interacting rock, water, air, and life.

Big Idea 4. Earth is continuously changing.

Big Idea 5. Earth is the water planet.

Big Idea 6. Life evolves on a dynamic Earth and continuously modifies Earth.

Big Idea 7. Humans depend on Earth for resources.

Big Idea 8. Natural hazards pose risks to humans.

Amid all the reflections on 2012, it’s hard to find evidence for an improvement in earth science literacy – in fact, the evidence seems to argue for the reverse. Loudest among the voices shouting for our attention are those of politicians with axes to grind and elections to win and those of the information-challenged electorates to whom they pander. And it’s easy (assuming, of course, that you agree with me) to focus immediately on the U.S., where the truth seems to increasingly go missing on a daily basis. But it’s not just there – the UK Government axes libraries and science funding and encourages schools to be run by people with an overtly religious agenda; the blitz of misinformation following the Japanese earthquake and tsunami was truly mind-boggling; Germany reverses its position on nuclear power overnight with no reference to science, risk assessment, or the environmental implications. And as for any international cooperation on management of our planet’s resources, well, I rest my case.

So, looking forward (as I prefer to do), here’s my fervent wish for 2012:

A YEAR FROM NOW, MAY A LARGER PROPORTION OF THE EARTH’S POPULATION SUBSCRIBE, SERIOUSLY, THOUGHTFULLY, AND ACTIVELY, TO THOSE BIG IDEAS THAN IS THE CASE TODAY.

Sandstorm

It begins with a dance. The wind playing games with the sand and the sand playing along. Ephemeral flurries, a shape-shifting fabric of turbulence, scurrying grains. It’s a compelling and alluring show, but, at the same time, as the wind gathers, the air begins to become oppressive and the brilliant blue sky takes on a threatening dullness as the cargo of dust changes the spectrum. The ephemeral flurries become continuous sheets of sand hurtling across the desert surface, assailing everything in their path. The sun is dimmed.

And then suddenly, seemingly out of nowhere, this streaming chaos turns into the full fury of a sandstorm, a full-blown assault, threatening everything.

Ahmed Hassanein Bey was a highly educated Egyptian, a diplomat and tutor to the king, but a man with deep Bedouin roots. He was the first to cross the Libyan Desert, from the Mediterranean to Sudan in a perilous eight-month journey by camel in 1923; in his extraordinary account of this journey, The Lost Oases, he describes the frequent sandstorms encountered:

It seems as the whole surface of the desert were rising in obedience to some upthrusting force from beneath. Larger pebbles strike against the shins, the knees, the thighs. The spray of dancing sand grains climbs the body till it strikes the face and goes over the head. The sky is shut out, all but the nearest camels fade from view, the universe is filled with hurtling, pelting, stinging, biting legions of torment...It is as though some great monster of fabled size and unearthly power were puffing out these hurtling blasts of sand upon the traveller’s head. The sound is that of a giant hand drawing rough fingers in regular rhythm across tightly stretched silk.

When a sandstorm comes, there is nothing to do but to push doggedly on. Around any stationary object, whether it might be a post, a camel or a man, the eager sands swiftly gather, piling up and up until there remains only a smoothly rounded heap. If it is torture to go on, it is death itself to halt.

During my expedition to the Western - or Libyan – Desert a few years ago, we were assailed by two full-blown sandstorms, the second one far worse than the first. In this age of motor travel, stopping is, unlike in the days of camel transport, the only option, unless frosted windscreens and severe testing of the seals of mechanical components are wished for. The system, well-practised by our drivers and guides, is to circle the wagons – form the vehicles into a square and lash large pieces of heavy fabric between them in an attempt to provide shelter. The attempt can only be partially successful - Hassanein Bey again:

The storm drives the sand into everything one possesses. It fills clothes, food, baggage, instruments, everything. It searches out every weak spot in one’s armour. One feels it, breathes it, eats it, drinks it – and hates it. The finest particles even penetrate the pores of the skin, setting up a distressing irritation.

Our real humdinger of a sandstorm, one that our guides ranked among the worst they had experienced, was in the White Desert, an iconic and spectacular landscape of white limestone sculptures, created by the wind with sand as its tool.

The wind had been gathering all afternoon, the air becoming oppressive, and the sky increasingly dull. As the storm gathered, I had stupidly attempted to put up a tent, but had to give up with the job only half-done. Determined to make the most of the experience, I huddled into the doorway of the semi-erected tent, wrapped a long piece of blue-dyed Moroccan cotton fabric around my head and face in an amateurish imitation of a Tuareg, and took out my notebook. The earth was on the move. As miniature sand dunes migrated past, and the hissing, spattering sound of the grains grew in volume, the burial process began. Piles of sand accumulated rapidly against my legs and began to weigh down the defenceless side of the tent. I tried to scribble down my account, but even a pencil had problems and sand accumulated in the hinge of my notebook (grains still fall out when I open it today). I watched some of my companions trying to put up their tent, and the drivers scrabbling to get some kind of shelter lashed down between the Landcruisers. There were no camels by which to judge visibility, but only during the occasional brief lull in the onslaught could this nearby scene be discerned with any clarity.

It was during one of these brief moments that, perhaps driven to dementia by the granular onslaught, I completely lost control of my senses and took out my camera.

There were two results of doing this – one photograph, and, ever after, a scratching sound when adjusting the telephoto lens.

I gave up, and battled my way to the shelter where my companions huddled, sharing the now very limited supplies of single malt whisky. Somehow, amazingly, in this mayhem, the cooks produced food; sleep that night was intermittent, but I remember being awakened at one point because the noise had stopped. And dawn was miraculous. There was no sign of the storm (other than the piles of sand marking buried tents), but rather a crystalline clarity, a sense that the desert had been cleansed.

 
And, suddenly, there was this colourful and fearless little bird strutting about in the sand – where could it possibly have sheltered overnight during the storm?

 

This was a staggeringly beautiful landscape, but one completely different from the previous day: immeasurable, unimaginable, volumes of the earth’s fabric had been moved, wholesale, from one place to another.

 

[This is my contribution to The Accretionary Wedge, December 2012, hosted by Ron Schott, with the theme “The Most Memorable Geological Event That You’ve Directly Experienced.”]

Nikon’s Small World – and other images

 
Each year, Nikon holds its Small World microphotography competition and the results can always only be described as stunning. This year is no different – but with the added element of sand appearing as the 14th place winner, the image above by Yanping Wang of the Beijing Planetarium.

Browsing through the galleries of winners, Honorable Mentions, and “Images of Distinction,” one of the (many) things that is striking is the art of nature’s patterns and designs, a theme superbly covered in the books by Philip Ball, Nature’s Patterns – A Tapestry in Three Parts. Scale has little role in all this, and I found it entertaining (not to mention awe-inspiring) to flip between the microscopic and the huge – specifically, the glorious gallery published earlier this year by Time, “Our Beautiful Planet: Images from Space by an Astronaut Photographer.” The images were taken by Paolo Nespoli:

European Space Agency Astronaut Paolo Nespoli — who first traveled to space aboard the Space Shuttle Discovery in 2007 — photographed a unique and stunning image of the space shuttle Endeavour docked with the International Space Station on a recent Soyuz mission. During a 159-day mission aboard the International Space Station, Nespoli managed to find time, despite his full schedule of duties, to capture footage for a documentary film, First Orbit. Combining historic voice recordings of cosmonaut Yuri Gagarin’s first manned spaceflight, the documentary charts the view that Gagarin saw during his historic mission. In addition to this footage, Nespoli also took many still images of Earth. LightBox presents a selection of these photos that show our planet as a beautiful abstract canvas.

“A beautiful abstract canvas” indeed; but then put some of these images together with the Small World – the viewer can be hard-pressed to determine scale at all:

Salar de Uyuni, Bolivia, Mar 2, 2011; Douglas Moore, University of Wisconsin - Stevens Point, Agatized dinosaur bone cells, unpolished, ca. 150 million years old (42x)

 
Dr. Juan Carlos Izpisúa, CMRB - Center of Regenerative Medicine in Barcelona, Neurons growing over astrocytes in a human stem cell embryo body (20x); Desert, Somalia, January 30, 2011

And then the “abstract canvas” is on display in quite extraordinary ways in the microscopic world:

Dr. Michael M. Raith, Steinmann Institut, University of Bonn, leucite crystal from volcanic rock showing polysynthetic lamellar twins formed by the cubic- tetrago (40x); Dennis Callahan, California Institute of Technology, Department of Applied Physics & Materials Science, Cracked gallium arsenide solar cell films (50x)

But, this being the blog that it is, I shall finish with the following image of sand dunes in Saudi Arabia – or is it actually a biological photomicrograph?

Sunday sand: ashes to ashes - and concrete

 
Continuing with my day out in Java, and geo-story-telling along the Cipimingkis River. The outcrops in the river are spectacular, a continuous tale of Miocene seas coming and going, leaving behind a sedimentary testament. The layers of rock crossing the river can easily be seen as the channel winds through the rice paddies in this Google Earth image:

 
I noted what a strange river the Cipimingkis is, a river not only bereft of sediment, but one whose channels have been mutilated by the excavation and removal of that sediment – sand and pebbles – leaving only pools between bare rock and the huge boulders that bear witness to the power of the river in flood.

It took me a while, but I eventually found small accumulations of sand that had not been stolen from the system, and there it is at the head of this post. A fairly nondescript-looking grey-brown sand that nevertheless tells, as usual, a tale. Typical of an immature river sand, there are grains of every size (it’s poorly-sorted), and, with the exception of the occasional grain of pale limestone, is made up entirely of bits of volcanic rock. Which is hardly surprising, for the Cipimingkis drains northward down from the slopes of one of the great volcanic edifices of western Java, Gunung (Mount) Gede. Looking upstream in this photo, in the distant haze (the contrast enhanced so as to make it visible) looms the huge – and active – volcanic massif, its location shown in the satellite image.

 

So these sands record one side of the battle of the mountains – destruction by erosion versus rejuvenation by eruption. The other thing to note about these young sands, only recently torn from the volcanic hinterlands and transported but a short distance, is that the grains are little worn, and preserve their sharp edges and angular character. They make an ideal ingredient for concrete and hence the thriving business in their wholesale extraction: the roads leading to this area are lined with piles of sand and laden trucks constantly labour ponderously along those roads. Volcanic ashes to alluvial ashes, to concrete – undoubtedly to be, one day, liberated again.

 

[Satellite image of Java from http://www.geoinfo.ait.ac.th/modis/modday2008.php]