Dust flux, Vostok ice core

Dust flux, Vostok ice core
Two dimensional phase space reconstruction of dust flux from the Vostok core over the period 186-4 ka using the time derivative method. Dust flux on the x-axis, rate of change is on the y-axis. From Gipp (2001).

Sunday, January 30, 2011

Sierra Leone not ready for foreign investment

A client of mine in Sierra Leone has just had two mineral concessions taken away for what are reportedly to be purely arbitrary reasons.

As the situation is still murky, it would be wise to reconsider investments in companies working in Sierra Leone. Companies such as African Minerals, with their gigantic Tonkolili iron deposit (and smaller Marampa mine) and Cluff Resources, with their Baomahun deposit, may be forced to reconsider the level of investments they will make to further the development of their respective properties.

More on this as developments proceed.

Friday, January 28, 2011

Identification of stone artifacts in coastal Ghana

Some months ago I posted some photograph of some interesting stone artifacts found in shallow offshore gravels in Ghana.

Here is one of those photos again.


A recent article in Wessex Archaeology's Dredged Up from the Past shows a similar stone found by a dredging operation. One of their more in-depth publications described the stone bead as a weight for a fishing net. Considering how common thrown-net fishing still is in Ghana, the fact that all of these were found offshore supports this hypothesis for the Ghanaian stones. 

Monday, January 24, 2011

Science—the new frontier for State aggression in the geopolitical age part 2: State aggression against individuals

Our last installment dealt with state aggression against other states. Today's installment will introduce the incredibly vast topic of state aggression against individual rights, a topic covered by numerous sites including Pro Libertate, Lew Rockwell, and others too numerous to list.

The most difficult problem facing the individual victim of state aggression--particularly in democracies--is the sense that any resistance is illegitimate. The problem is commonly worsened by the fact that the State will often refer to some scientific evidence as "proof" that you need protection from some entity or action. Opponents to State policies are, therefore, irrational as well as illegitimate.

The following is a partial list of State policies which are backed by scientific studies, against which any protest is considered both irrational and illegitimate:

Fluouridation of drinking water (in North America)
Composition of the food pyramid
Global warming
Mass vaccination of children
Approval of aspartame
Encouragement of statin drugs
Widespread use of dental mercury fillings
Use of fiat currency
Approval of GM foods

The discussions below are really brief and are not intended to be full treatments of the subject matter.

Fluoridation of water

The fluoridation of water has been proposed to reduce cavities in populations. Opposition to the fluoridation of water is based on ethical grounds (the difficulty for individuals to opt out of the program, lack of informed consent, and the lack of control over dosage); efficacy (it is proposed that fluoride should be applied topically to teeth rather than being ingested); and on health grounds (ingesting fluoride may be unhealthy).

Many Western Europoean countries oppose fluoridation of water for the reasons listed above.

The position taken by typical health officials in North America is reflected in this statement by the former Medical Officer of Health of the City Waterloo, "Every reputable scientific authority throughout the entire world strongly advocates the addition of fluoride to the water." Such a statement is tailor-made to discredit any attempt to oppose the concept of fluoridation.

By contrast, the statements made in position documents of DVGW in Germany question the above statement. They do not specifically discount the effect of fluoride on cavities, but do argue that the additional possible medical, ethical, and environmental costs of fluoridation cannot be justified. 

Food pyramid

I remember reading an article many years ago in which a Canadian nutritional researcher stated she was forced out of her position because she claimed that the food pyramid did not reflect the actual nutritionists' advice, but was largely shaped by commercial interests. Unfortunately, I have been unable to find this story again--it is gone into the memory hole.

There are articles by Dr. W. Willett of the Harvard School of Public Health arguing for substantial modifications to the food pyramid, including reducing grains and increasing the amount of fats (albeit plant oils) in the recommended diet.

Global warming

I hardly even want to talk about this one. Suffice to say there is a tremendous amount of emotionally charged debate on both sides and ridicule for anyone who dares contradict official pronouncements. Do your own due diligence.

Mass vaccination of children

The number of different vaccinations recommended for children has ballooned over the past several years.

Each of the new proposed vaccines has one or more scientific studies supporting it. Each vaccine, in isolation, may provide a benefit with a reasonably low risk. What is less well-known is the cumulative effects of the large number of vaccines that very young children receive.

In addition, there are reasons to oppose this increase in vaccination. Such arguments include (but are not limited to) the effects of mercury-based preservatives on neurological development; the relationship between vaccination and autism (which may have been refuted); the serious side effects of the flu vaccine, among others; and the effects on the developing immune system of a massive wave of vaccinations.

Approval of aspartame

Aspartame is one of the most widely used artificial sweeteners on the market, yet its original approval for commercial use by the FDA was heavily contested. Searle (now part of Monsanto) won the day thanks to Donald Rumsfeld's influence, who some say should have a metabolic disorder named in his honour.

In the early 1990's, lab technicians at the lab above mine at University of Toronto reported that rats showed terrible toxic responses to moderate doses of aspartame. One day one of the grad students at the lab in question told me that they had been threatened with immediate loss of all research funding unless they stopped working on aspartame.

Statin drugs

Statins are used to reduce cholesterol. In your blood tests, cholesterol is divided into two types; the high-density lipoproteins (HDL) and the low-density lipoproteins (LDL). Simplistically, HDL is referred to as "good" cholesterol and LDL is "bad".

Even within the "bad cholesterol" there are two distinct types--pattern A, which consists of larger and less dense LDL particles, and pattern B, consisting of smaller and denser LDL particles. Of the two, only pattern B is associated with elevated risk of coronary disease, but the cholesterol blood test is unable to distinguish between the two.

Doctors normally recommend any patient with elevated LDL to take statins. The actual level of LDL that is considered to be elevated has fallen over the past decade, meaning that the number of people recommended for statin therapy has similarly increased. But simple blood tests are unable to distinguish between pattern A and pattern B LDL, so patients are asked to risk serious side effects to take a drug that may not actually be necessary.

Science and public policy

As I mentioned above, once a public policy is backed by science, it becomes illegitimate to protest it. What makes this dynamic particularly troubling is that there is a reinforcing dynamic between government and research labs whereby the labs are encouraged through receipt of government funding to produce results which favour government policy. Additionally, certain large industrial interests also fund research which favours usage of their products (whether they be agricultural, pharmaceutical, or military).

Even if researchers begin to produce results at odds with the scientific consensus, it can be difficult to bring about lasting change.

Update: January 25

Here is another article that makes the same point

Saturday, January 22, 2011

Determining scale invariance in geological phenomena

One concept which is quite familiar to geologists (even though it isn't often explicitly stated) is the concept of scale invariance. The way in which this point is frequently hammered home is through the requirement of a scale in a geological photograph. The reason that a scale is required (this need not be a literal measurement--frequently it is an object of known scale, like a shoe, a person, a rock hammer, a coin, or a house) is because many geological phenomena occur across a wide range of scales.

The picture at left is a perfect example. I found it on the internet years ago, and actually now I can't remember what it is. I have no idea if this is a close-up of the beach with a field of view of under a metre, or whether it is an aerial photograph, because features that look like those at left can occur at all of those scales.

The recognition of scale invariance in natural phenomena is not new. Benford's Law, an empirical relationship first noted by Newcomb whereby the first non-zero digit of a measurement is more likely to be 1 than 9 (30% vs 4.5%) is now understood to arise as a consequence of scale invariance.

Benford's Law only holds if the size range of the features measured spans several orders of magnitude (i.e., it does not apply to human heights).

Although scale invariance is inferred from the need for scales, obtaining the actual proof that geological phenomena are scale invariant is not easy. The reason for this is that the scale of observations available to the typical geologist is very limited.

The majority of geologists deal with rocks in outcrop, or (worse) sections of rocks obtained by drilling. In some parts of Canada, we have it pretty easy, as outcrops are frequently substantial. But in many places, most of the rock is covered in swamps, lakes, talus, mud and sands, or is inaccessible for other reasons. In such places, individual outcrops might only be a few metres across. Assuming a certain amount of weathering, it may be very difficult to identify very small features. You may only be able to observe features like fractures, or folds, across one or two orders of magnitude. This is not sufficient to determine scale invariance.


The photo above shows a number of olistoliths (two are outlined in red), which are pieces of material incorporated into a landslide that happened in the past. The olistoliths and the surrounding material were all soft (mud and sand) at that time--they are rock now. Some of the olistoliths in the photo are laminated, and these lamina are deformed somewhat, testifying to the stresses that these olistoliths underwent during their emplacement. The hammer is there for a scale. Photo is of the Gowganda Formation, near Whitefish Falls, Ontario.

In the photo above, the largest olistolith is about five times bigger than the smallest observed.


Here are olistoliths observed on the split face of a piston core sample from the Nova Scotia continental slope, collected in early 1987. The sediment is unconsolidated (still mud). The scale is at the bottom of the photo, measured in cm. These olistoliths are smaller than the ones in the Gowganda Formation, but still pretty much the same order of magnitude.

Smaller features are potentially visible in core, but they can't get much larger before they get difficult to identify. If the olistolith above were about 30x bigger than the one's that are present, in the core they would look like a separate layer, rather than an olistolith. Again, it is difficult to infer the scale-invariant nature of olistoliths from only these observations.

How do we see larger features in marine sediments? We have to go to geophysical imaging methods, and the two most common are seismic profiling and sidescan sonar.


The above profile is one I worked on in the late 1980s, although it had been collected some years earlier by the Geological Survey of Canada. The image has been vertically exaggerated, so that the space beween each of the tick marks at the extreme right of the image represents 10 m, whereas the length of the image is about 4000 m. There are a few debris flows interpreted to be in the image, two of which have been labelled. They are fairly large, compared to the photographs we have of olistoliths, and it would be reasonable to presume that there are large olistoliths within these debris flows. Unfortunately olistoliths do not show up on seismic profiles, so we don't know.


Not too bad. This is something similar--a pile of material that slipped downslope (that thing that looks a little like a footprint just left of centre of the photo). From the Gaskiers Formation (of Neoproterozoic age) outcrop on Little Colinet Island, southern Newfoundland, taken in 1995. I wouldn't quite call this an olistolith, but it is close.

It would seem the only way to confirm the existence of larger olistoliths is by studying very large outcrops with excellent exposure. These are generally rare, but below we'll take a look at two of them: the Smalfjord Formation in Arctic Norway, and the Yakataga Formation in the Gulf of Alaska.

Neoproterozoic diamictites of the Smalfjord Formation, northern Norway.
 The light-grey areas represent rafts of sediment carried downslope in debris flows.
The red blotch at lower left is a person crouched over taking notes.

The sedimentary blocks in the Smalfjord Formation are pretty large. The ones in this picture appear to be about 2 m thich and perhaps 10 m in length.

1500-m section of the Miocene-to-Recent Yakataga Formation near Icy 
Bay, southern Alaska, taken in 1989.



Outcrop on the scale of the image above may be what the doctor (that's me) ordered.

Exposure of Yakataga Formation at Icy Bay, Alaska, showing a submarine canyon and a series of olistoliths. Overall section here is about 1500 m in height, making the largest olistolith some 200 m in length. Original photo from an N. Eyles paper (trying to figure out which one).

We can demonstrate directly that there is a wide variety of sizes of olistoliths, but we have a hard time doing it from a single outcrop.

At this point we don't know anything about the size-frequency distribution--a topic we'll come to another time.

Friday, January 21, 2011

Captain Bernanke and the Black Hole of Negative Real Interest Rates

I hear Disney is finally remaking "The Black Hole". If so I have a few suggestions for slight alterations to the cast and plot to bring the movie up to date.

In this version of the movie our heroes find a vast, derelict ship, the US Economy, locked in orbit around a massive black hole. Although the ship appears to be dead, it soon comes to some form of life thanks to Quantiative Easing.

 The US Economy drifting around the black hole of negative real interest rates.

Our heroes land aboard the US Economy and make their way to the bridge, which they find under the ship crewed by zombie banks under the command of Captain Bernanke.

 Captain Bernanke and one of his crewmembers.

Captain Bernanke's right hand man is a robot, the lethal Geithnertron.

"I've heard enough! Geithnertron! Bring me the heart of Ron Paul!"

Our heroes are astonished to hear that Captain Bernanke intends to pilot the US Economy right through the black hole. Their protests that the ship will be destroyed by the incredible deflationary pressures are dismissed by Captain Bernanke, who has been developing new economic theories over the past twenty years and is now determined to show the power of Keynesian economics.

"The deflationary pressures will destroy the US Economy before you cross the event horizon!"
"Our engines can generate enough QE to counteract any deflationary stresses."

Captain Bernanke believes that once the US Economy passes through the black hole, it will pass through into a new Universe of Limitless Possibilities.

"My theory produces a desirable result; therefore it must be true!"

Eventually our heroes uncover the uncomfortable truth about the zombie banks.

"Oh my God! There's nothing in here but non-performing mortgages!"

Captain Bernanke tries to make them into zombie banks as well!

Zombification via deadly TARP rays.

Our heroes must attempt to escape before the US Economy plummets into the black hole. The ship is pummeled relentlessly by meteorites, and segments of the ship give way.

"There goes the Unemployment data!" (graph from BLS data, explanation here).

With their own ship destroyed, and the US Economy collapsing around them, our heroes search for a lifeboat. Luckily, they have a little gold stored. They suffer intense criticism from financial commentators in the media for their faith, but fight their way through.


"We got our gold. Let's get out of here!"

Unfortunately they too close to escape and are forced to go through the black hole.



The US Economy begins to break up.

In the final (much-debated) metaphysical sequence, we see what happens to Captain Bernanke and Geithnertron after passing through the black hole. They are united into one being, left standing atop a mountain, surrounded by the zombie banks (one presumes for eternity).

Bernanke, Geithnertron, and the zombie banks, surrounded by the 
fires of Hell, fueled by the endless burning of paper.

Our heroes, however, protected from deflationary pressures by gold, enter the Universe of Limitless Possibilities.



- - - - - - - - - - - - -
Negative real interest rates refers to the difference between a popular interest rate (say the 3 month Treasury rate) and the inflation rate (normally CPI, but better to use some measure of real inflation).


Monday, January 17, 2011

The meaning of Schools in the Sciences--and its Implications for the Dismal One

Schools and paradigms in science

Nowadays, most people think of scientists as being relatively uniform in thought and deed. They may read of a "scientific consensus" about issues like global warming, acid rain, and so forth. Any scientist who does not agree with the scientific consensus is presumably one of those mad scientists out to destroy the world or remove fluoride from the drinking water. (that is intended to be ironic).


But science wasn't always this way. Eighteenth century geologists were divided into schools, each of which had their own unique way of looking at rocks and interpreting the history of the world. The Neptunists, led principally by Abraham Werner, believed that all rocks were formed in the sea, either by deposition of sediments, or by precipitation from solution (both well-known processes at the time). By contrast, the Plutonists believed that rocks were formed from magma.

Most students of geology learn about these two schools (as well as two other competing schools--the catastrophists and uniformitarians) in introductory geology courses, but what is never discussed is the deeper philosophical significance of having these competing schools in science.

After all, we don't have competing schools in geology now. That is not to say that everyone agrees about all topics all the time--nothing could be farther from the truth (trust me on this--I go to conferences all the time). But there are no disagreements on the scale of requiring an entire school of geology which interprets all observations in one way as opposed to another school which will interpret the same observations differently. It seems impossible to have such structures in a science that is based on attempting to learn about the Earth through observation. What we have now . . . well, I'll get to that later.

The fundamental difference between geology now and geology in the 18th century is that the 18th century schools of geology were really based on formal systems. They were based on a logical system consisting of a set of irreducible statements, or axioms, which represented fundamental truths; and a series of rules of inference, which allowed new theorems to be proposed. Observations were used occasionally to justify one of these proven theorems. Anyone who accepted the axioms and rules of inference would logically move from one conclusion to another, and as the axioms were true statements, and rules of inference were designed to generate true statements from other true statements, any theorem generated by the formal system had to be true.

The difficulty in these systems is usually in the truth of the axioms. Rules of inference are almost always logical and work as desired (but see this story by Lewis Carroll for an argument against even the simplest rule of inference). As the statements were irreducible, they were unprovable. They had to be accepted on faith. Frequently, observations which disproved some theory would simply be explained away.

Why was science practiced this way? The scientific method was known at the time, and bodies such as the Royal Society strongly favoured this approach to science. My thinking is that the interpretation of geological observations was not sophisticated at the time, making the ideal approach to science impossible.


The practice of geology has changed fundamentally since then. And yet . . . you can still say there are schools in science. The only difference is that virtually everyone practices within the same school.

We call such schools paradigms. They differ somewhat from the older schools in that they are not based on formal systems--there are no axioms in which its practitioners keep faith. But a paradigm still places limits on scientific endeavour--it limits the types of questions asked; the way in which they are asked; and the means by which they are answered. In principle, any paradigm can be overturned by a single observation; but in reality overturning a paradigm is something that can take dozens of scientists decades (and oftimes professionally painful decades) to accomplish.

In geology, the plate tectonic paradigm is the framework within which field observations are fitted. Frequently there are some observations that don't agree with the paradigm as it is currently understood, but the paradigm concept is flexible enough to allow for a little bit of tinkering. The trouble may start when the inconsistencies start to do violence to the paradigm (see The Scientific Method and the Human Condition). Defenders of the paradigm will point out that there are literally thousands of peer-reviewed papers that have been published demonstrating that some local field observation can be explained by plate tectonic theory--strong support indeed. However, since the papers were written to fit the paradigm, then logically they should not be considered to be honest support for the paradigm.

The biggest paradigm of all in science is the Newtonian paradigm--the mechanistic view of the world. It is so large and pervasive that probably most scientists don't really think about it. Yet it just may be that this paradigm is beginning to shift.

The Dismal Science

Economics as a science still seems to be divided into numerous schools, each of which has varying successes in predicting economic behaviour. There are actually more schools than I had believed possible considering that all there is to economics is trying to figure out how humans are going to choose between alternatives in a resource-limited world.

The principal differences between the schools are in their axioms--in particular, each school has axioms which state which criteria are important when a group of humans has to choose between alternative courses of action. Different schools posit that humans base their choices on different criteria, or possibly weigh them differently.

For instance, some schools of economics consider only the opportunity and input costs for a project against the benefits. Other schools would add the costs to the environment of the project, and may well arrive at a different conclusion for the viability of the same project.

To argue about which of these schools is right is impossible, especially for an outsider--all you can do is choose the one which is closest to your own values.

To a geologist (me), this freedom to choose your reality makes it difficult for me to consider economics to be a science. At the same time, I see it as a logical way to make an economic decision. If, for instance, I decide to open a mine in Ghana, I have to decide which economic method to apply when I compare the benefits to the costs. I may have decided to include the environmental cost in my calculations of mine viability, and there are consequences to that decision--it limits the location of the mine and the style and scale of operations. Possibly another geologist would not consider the environmental costs, and would arrive at a different model for the mine. Yet both of these are viable alternatives within these different economic views.

Just don't expect me to consider economics to be a science.

Praise from Gonzalo Lira! But . . .

For a comment on his article "Why democracies will always go bankrupt" available here.




mickeyman said...




I think the problem is that economics, which seems that it should be an observational science, is in reality a formal system with axioms and rules of inference. All of the different schools of economics only differ in their particular choices of axioms. If the axioms are actually false statements, then the system generates absurdities, the result of which we can see all around us.


Gonzalo Lira said...




Mickeyman,

You've written the smartest thing of all the comments—you've successfully diagnosed what's wrong with economics as a discipline: "A formal system of axioms and rules of inference. All of the different schools of economics only differ in their particular choices of axioms. If the axioms are actually false statements, then the system generates absurdities, the result of which we can see all around us."

Exactly.

GL

Sunday, January 16, 2011

Reconstructed phase space of BLS unemployment data

Every so often you witness a change in the dynamics of a system that is so breathtaking you can't help but feel fortunate to witness it.

Perhaps this is an exception.

Data available from the Bureau of Labour Statistics over the past ten years can be used to show the dramatic change in the employment picture over the past two years, showing just how much worse the current recession is than the post-2000 recession.



It's like entering a whole new world. By comparison the recession to 2004 was like Disneyland.

Two points that are nearly juxtaposed are July 2002 and July 2008. In the first case, we were nearly at the worst part of the recession, but six years later we were only just starting.

Unfortunately for the US, it looks like an area of Lyapunov stability occupied from 2002 to early 2008, rather than representing the height of unemployment now looks like the new low. And the cluster of points we see since April 2010 may be the beginning of a new LSA. We may be here for awhile.

And we're still waiting for those low interest rates to reduce unemployment.

Saturday, January 15, 2011

Self organization in geological phenomena, part 2: stone and soil stripes

Today the World Complex travels to Antarctica (via the wayback machine, to 1993). (Maps were prepared for some presentation given at about that time).

At the end of the Antarctic peninsula (around 60 W and north of the Antarctic circle) there is a grouping of islands called the South Shetland Islands.




One of the South Shetland Islands is called King George Island. It is dotted with research bases, including Marsh Station and Ferraz Station. The Brazilians had a research base within Admiralty Bay serviced by a naval vessel called the Barão de Teffé.

Brazilian research vessel Barão de Teffé in Admiralty Bay (viewed from shore).

I spent six weeks in the field with a team of Brazilians on a site near Mazurek Point. It was one of the best-supplied field camps I've ever experienced (only Ice Island was better supplied, but the Brazilians outdid us Canadians by supplying abundant--really abundant--wine and chocolate).

Six of us at Marsh Station (the seventh, Jefersòn, took the picture). 
I am at the left, along with Paulo dos Santos, Antonio Rocha-Campos, 
Roland Trompette (famed for his West African work), Ricardo (our mountaineer), 
and Alexandre Uhlein.

 Iceberg with supply helicopter for scale, viewed from our base camp.

The goal of the project was to study the Polonez Cove Formation, which mainly consisted of interbedded diamictites, turbidites and volcaniclastic flows of Oligocene Age. Actually, at the time, the age hadn't been completely established.
 
The base camp was set up on Low Head (that little x near the bottom of the map). Most of the areas of interest were in the numbered sites along the coast running up the right edge of the map.

Wypianski icefall, which will play a role in a later posting, pretty much covered up anything of interest. The interesting rocks were exposed along the coast from Low Head, across Mazurek Point and on up to Lions Rump at the top of the map.

But that irregular area marked SSSI (site of special scientific interest) was off-limits to us, as it was a sea lion breeding area. Unfortunately, there was a very interesting geological transition close to the boundary, where we found a series of stacked debris flows interbedded with turbidites intercalated with a series of volcaniclastic flows coming in from another direction.

But geology sometimes has to yield to biology.

Luckily, we went in summer.

The snow cover was ephemeral. When the snow disappeared, on a slope not far from the base camp you would see these . . .

Soil stripes near Low Head, KGI.

They weren't actually a target of our study, and to be honest, we didn't know what they were. What we observed looked like ripples, with alternations between gravel and lichen- or moss-covered silt. They were oriented perpendicular to the slope and were consistent in thickness and composition over a distance of tens of metres.

Details of soil stripes

Further upslope where the debris was much coarser (fresh angular cobbles), there were similar, albeit larger structures.

Stone stripes, KGI.

I had originally thought this to be a form of fluting, however all of these rocks, which have been shed from the ridge at the top right of this photo, are actually lying on top of ice, albeit a long way down. This patterning is formed by a succession of freeze-thaw cycles, which result in sorting the rocks as they move downlope. Similar images can be seen here.

Formal explanation for these features was published in Nature in 1993, so I had a nice read when I got back home.

Self-organization in geological phenomena, part 1: Rhomboidal rills

Beaches in Ghana commonly show an amazing pattern of light and dark sands which are caused by the interaction of water flows as waves recede from the beach.


Rhomboidal rills on a beach in Ghana. The sea is toward the top of the photo. 
The light scuff mark at lower right is part of a footprint for scale.

The patterning is composed of regions of black sands, which are heavier minerals (and usually small grains), whereas the lighter-coloured grains are lower-density, rounded silica grains.

I have never observed this sort of patterning on beaches anywhere else. However there is something of a geological literature on these features dating back to the 1840s.


Oblique view of rhomboidal rills on beach surface, western region of Ghana.

Based on the paper referenced above (which appears to be a class project), the features form during the waning flow phase (as the wave finishes retreating) over a deforming bed.

The last point is significant, as it implies that the deforming bed (in this case, sand) is affected by the flow in a manner that feeds back and influences the flow.

What observations support this conclusion?

First of all, rhomboidal rills don't form on all beaches. In Ghana we observe them on beaches with a very low gradient, and the grain size is usually in the fine sand range. In my experience on some Great Lakes beaches, the beach gradient is high and the material is very coarse, but such beaches have no rhomboidal rillls.

My own observations of these forms occurring on beaches led me to conclude that they form under laminar flow conditions, when the flow thickness is small.


Photo taken as wave flows out, showing organization in the flow. 

The principal idea in the paper referenced above is that the organization in the flow arises from a random assortment of "rises" on the surface of  the water at the moment the wave has reached its high point on the beach. The "rises", or area where the water flow is a little thicker than elsewhere, result from random motion within the wave.

When the wave begins to recede, relaxation of the flow causes a local flow of water away from the centre of the each of the rises, while simultaneously the entire wave begins to flow back towards the sea.


In the diagram above, the small circe at the top represents the rise in the brief moment the wave is at rest and before it begins to flow back towards the sea. Water flows away from the centre of the rise (circles) but also flows downslope, resulting in a thin triangular flow defined by a characteristic angle, which is probably related to the gradient of the beach.

If the gradient were steep and the flow thick, the sides of the flow would form a parabola, and such forms are seen on beaches where fixed objects (say rocks) are washed by waves. As the wave flows around such a fixed obstacle, we observe a parabolic flow seaward of the object. On these Ghanaian beaches, the flow characteristics are such that the water flow is a thin film, flowing at low speed, and viscous drag reduces the acceleration so that the edges of the flow appear to be straight.


Now let us imagine two of these angular sheet flows interacting. At the point of intersection there is a sudden acceleration in the flow, as we now have twice as much water moving over a given area. This can only be accommodated by an increase in flow velocity, or an increase in thickness. Momentarily, both are observed. The increased flow results in erosion (E), preferentially of lighter material.

On the Ghanaian beaches in question, the sands are comprised of brown quartz sands (light) mixed with fine heavier black sands (including higher-density magnetite, ilmenite, rutile, zircon, garnet, and sapphire). The erosion removes the quartz sand, leaving behind the darker heavy minerals.

Immediately downslope of the intersection, the angular flows diverge, and the flow thins and slows. As it slows, the quartz sand grains picked up by the flow are deposited.

In this figure I have drawn in the edges of some of the thin angular flows that generated the rhomboidal rills in the photograph. Note the darker sands occur near the intersection of the angular flows, and the lighter sands farther downslope and often to one side of the divergent flow.

Rhomboidal rills are formed by self-organization in wave flow.

The features are destroyed and reformed by subsequent waves.


Hints of organization in the receding wave.

The organization in the receding wave is apparent at the right of the following video (all in the first four seconds).

video

I spent half an hour filming every wave that came in and none of the videos where I tried to capture the self-organization in the water flow worked except for the one video shown here. And when I filmed this one, I thought at the time that I had missed it!

Unfortunately the loss of resolution in posting this video makes it unconvincing


Screen capture of video 2 seconds in. Note overlapping angular flows at right.

Update: more photos of rhomboidal rills here.

Thursday, January 6, 2011

Science—the new frontier for State aggression in the geopolitical age

You remember the events of two years ago, when an American vessel ran afoul of some Chinese “fishing vessels”. The USNS Impeccable, an ocean surveillance ship, was monitoring submarine activity south of Hainan in March 2009, when numerous Chinese vessels began to shadow and harass it. The Impeccable replied with water cannons.

A similar incident happened to the USNS Victorious in May 2009.

Much was made of the unarmed nature of these vessels. But look at their pictures.

There seem to be a few odd pictures in the above link.

Arguments have been made by both sides as to who was in the wrong, and it may be that under the UN Law of the Sea that the American Navy had a right to carry out its operations within the Chinese Exclusive Economic Zone; but I had to applaud the Chinese for trying to stop these vessels from their mission.

It is disingenuous to carry out work which is clearly aggressive, and then deny it by saying you are permitted to do so. Hunting for submarines in a section of the ocean far, far, away from your own could indeed be considered to be an act of aggression.

But what if the vessel were actually an oceanographic survey vessel? Could something as noble as gathering scientific data be considered an act of aggression? Let's consider.

Russians on the Grand Banks

In June of 1986 I was a member of the scientific staff on board the CSS Hudson, a Canadian oceanographic vessel (now called the CCGS Hudson).


CSS Hudson enters St. John's harbour May 1987 with surviving crew 
members of the Skipper 1. Photo by me.

The mission involved mapping and exploration of the seafloor on the Grand Banks through a combination of sidescan sonar and seismic profiling, combined with core collection. We sailed from St. John’s, tailed by a Russian oceanographic vessel called the Passat. During the entire mission, the ship (or another like it) would appear near the horizon, but always stayed several km away.

Composite image of the Musson, docked in St. John's harbour in late 1987 
(about sixteen months after the events of this story). Photos by me.

Officers on the Hudson commented that Russian oceanographic vessels were on the Grand Banks at least 300 days a year. By contrast, Canadian research vessels surveyed the Grand Banks for less than 30 days per year.

One of the scientists on board related how the Russians used to steal ocean monitoring devices left behind by Canadian vessels. The instrument package was attached to a weight by a cable with an acoustic release. The instrument package had a float, so when the acoustic release was triggered, the package would float to the surface. On the cruise in question, the scientist observed the Russian ship always near the horizon, passing over locations where the instrument packages had been placed. When the Canadians went back to pick up their instrument packages, they were all gone.

There were other stories of how during testing of one of the later Huntec systems, the prototype of a newer form of their deep-towed system, the ship was surrounded by Russian trawlers and other vessels, some with nets deployed, and the equipment was lost. This event supposedly happened in April 1981.

The Russians (when they weren't stealing or sabotaging equipment) could have been carrying out innocent scientific research. What research could that include?

There is a long history of collecting weather data in the North Atlantic for the purpose of forecasting for Europe. Weather collection could be for civilian or military purposes.

What about seafloor mapping? A noble endeavour, no?

On this 1986 cruise, we mapped out several submerged fjords, at the edge of the continental shelf. The internal geometry of these fjords was very interesting, but it was clear that our instruments were unable to image the walls or bottom of the fjord accurately. 

There was nothing unusual about this--the distortion is a function of the geometrical relationship between instrumentation towed near the surface and the relief of the seafloor. Basically, the greater the distance between the sonar and the seafloor, the less representative the sonar returns were. Over most areas, where the seafloor is relatively flat, this wasn't a problem. But where the seafloor is very rugged, the distortion may be significant.

In the case of our undersea fjords, our instruments were incapable of seeing the bottom, because of reflections off surface irregularities in the walls of the fjords. This can only be overcome by towing the sonar within the fjord close to the bottom. 

There is a correspondence between the type of sonar we were using and the type used by, say, a destroyer looking for a submarine. If our sonar is unable to see to the bottom of the fjord, the same will be true of the standard anti-submarine sonar. Mapping the location of these things could come in handy if you were looking for a place to hide, say, nuclear submarines on the edge of the continental shelf of some future adversary.

Soil cadmium and Canadian wheat

In 1994 I was about to carry out an exploration program in Northern Ontario for a Canadian mining company. The program was a large-scale reconnaissance project bent on recovering diamond indicator minerals from glacial till, but the samples were to be assayed geochemically for various elements of interest. I decided to discuss sample location distributions with a friend of mine at the Geological Survey office in Ottawa.

At the time the GSC had recently completed a soil survey over western Canada, and were still compiling the results. But one issue in particular was causing a great deal of grief.

The European Union was proposing to decrease the acceptable levels of cadmium in all wheat imports. Cadmium is a metal, and like all metals is toxic in sufficiently high doses. Unlike many metals, however, cadmium is not necessary for human life, and as it can accumulate in tissues in the body, it makes sense to reduce your intake. But to suspicious eyes (most of which were Canadian), the proposed cadmium restrictions appeared to be very carefully selected to exclude Canadian durum wheat from the European market while not excluding Russian wheat.

Part of the reason for the GSC survey was to try to find the source of the cadmium. The results were discouraging. It appeared that the cadmium had been spread by glaciers after advancing over a particular black shale unit in the Manitoba escarpment. Since the cadmium was natural, and spread all over the Canadian plains, there was no feasible remediation. (although see this for some recent progress).

There was initially a lot of crying over the cadmium in Canadian wheat issue. But the Canadian government came up with a brilliant plan. In March 1995 they began siezing Spanish trawlers fishing at the edge of the EEZ. There was a great to-do, climaxing with Brian Tobin's tour of New York with a Spanish turbot fishing net. In the aftermath, the whole cadmium issue disappeared, and there was a signed agreement regarding fishing stocks that straddle lines of jurisprudence.




This is more my speed nowadays. Fishing off the coast of Ghana. Photo by me.