Did you know? #Louisiana is disappearing

SE_LA_landloss

Land loss map of South Louisiana. Image source here. Click on image to enlarge. 

Is it the weather? No fewer than three long, detailed and well-researched articles in important media discussed the continuing story of increasing land loss in South Louisiana. The Globe and Mail’s Omar el Akkad wrote an insightful piece about disappearing Louisiana in the October 18 paper. The October 5 New York Times Magazine’s main article was a heart-sinking rendering of the fight of a few individuals against the sheer unwillingness of anyone to do anything to save the State of Louisiana. The New Republic Magazine ran an article on September 30. The latter two articles particularly focused on corruption.

All three articles were excellent, so why should I want to add anything?

I am a sedimentary geologist. I worked for the Louisiana Geological Survey from 1981 to 1986. Most of that time I worked on marshes – disappearing marshes. I was one of a team of about 6 young ambitious geologists, brought together under the Louisiana Geological Survey’s Coastal Geology Program, an initiative to inventory and understand the causes of the State’s land loss.  We were not the only official program working on these issues in the State at the time. We cooperated with the Louisiana Universities Marine Consortium (LUMCON), with scientists at Louisiana State University’s Coastal Studies Institute and with its Centre for Wetland Soils and Sediments. And that’s not counting the – Federal – US Geological Survey and the US Army Corps of Engineers. We worked on barrier islands, hurricane effects, sediment budgets, marsh dynamics, nearshore currents, river dynamics, you name it.

Did we come up with new information? I think we did, if only for the sheer volume of new data that we gathered, analyzed and published, both as technical reports and as articles in internationally peer-reviewed scientific literature. There were a couple of new ideas and new insights, but I think it’s realistic to state that we mostly added lots of data and lots of detail to a story that was basically known and accepted by the mid 1960’s: the Mississippi Delta consists of ephemeral land because the river is – as Omar El Akkad wrote – a ‘side-winder’ and has been prevented from behaving as such for several centuries because of levee-building by its inhabitants. Thus, the vast amounts of river sediment are dumped in 4,000 m water depth off the present-day river mouth (which is completely artificial) rather than being available for nourishing the delta plain’s marshes and bays (important nursery grounds for the fisheries) and its skimpy but crucially important barrier islands and beaches (I wrote about the fragility of Gulf of Mexico barrier islands here: http://earthsciencesociety.com/2013/02/20/barrier-island-erosion-sea-level-rise-transgressive-anthropogenic-sequences/).

MissDeltalobes

The Mississippi Delta is a side-winder. Depicted are the 5 main Holocene (less than 10,000 years old) delta complexes each with a number of individual delta lobes. The oldest delta complex, the Maringouin, has subsided and is below sea level. If the Mississippi would not be confined by artificial levees, it would have switched back to the Maringouin area by now: the present day Atchafalaya river and delta (entering the sea at about no. 12 of the previous Lafourche complex) occupies that position but river locks only permit it to carry a fraction of the total river load. That route, the preferred one by the river, is 250 km shorter to the sea than its current route. Image by Louisiana Geological Survey.

We knew this 30 years ago. We were never prevented from communicating these observations to the general public by the way. In fact, we were encouraged to do so and I clearly remember a TV crew in our core facility. Our director (who later became a USGS director) didn’t tell us what to say to the press – ever. The most vocal member of our team even got a New York Times Obituary when he passed away 8 years ago.

We did not think climate change back then. But you don’t need rising sea level to declare an emergency: the Mississippi Delta is sinking because its sediment is waterlogged. Natural compaction squeezes the water out and makes the land sink. If you prevent the delta and the coastline from being nourished by its own sediment, the land loss due to compaction will be exponentially worse. If you let the oil and gas industry dig thousands of kilometers of canals, which disturb the delta’s hydrology, enabling salt water to penetrate landward, thus killing marshes and generating open water bodies, then you really have a problem.

Lies in Flotant 1

Author negotiating a disappearing marsh in the Mississippi Delta in 1984. This particular area was becoming infiltrated with salt water at the time, and this killed the fresh-water vegetation. It is now open water.

Hurricane Katrina slammed into Louisiana 9 years ago this summer (August 28). You’d think that that catastrophe would have led to some action. It didn’t. Some engineering companies got a few contracts. But soon after Katrina, people in power got really tired of scientists telling them why the land was disappearing. Louisiana State University even fired a tenured professor who told the truth, but had to pay him a hefty sum in damages a few years later. In the Globe and Mail article, Louisiana Governor Bobby Jindhal is quoted as saying that the oil and gas industry provides 60,000 jobs and therefore shouldn’t be the only actor pay the price for this catastrophe. He suggests maybe the fishers should pay a price as well. Really? Since when have fishers wealthy shareholders and corporate exit bonuses? That was just political distraction tactics by th governor. Because the truth is, you can’t allow the river to switch to its preferred location (the Atchafalaya course) because from Baton Rouge southward, the river would fill with sediment, New Orleans as a harbour would have to disappear and since it’s the lagest bulk port of the US, that’s unaffordable.

Is Louisiana an exception in the world? On the margin, I don’t really think it is. It’s true that Louisiana is an eccentric State. It is the only State in the US with a legal system based on the Code Napoleon rather than on the Anglican Code and so all its legal experts are educated in Louisiana and this leads to professional inbreeding and corruption. That’s not a secret. So it’s a bit of a banana republic. It also has way too many very poor people, which is entirely unnecessary given its petroleum wealth, but there you go – that’s Louisiana.

After Hurricane Katrina, I developed a talk on the catastrophe. I gave that talk several times as a fundraiser. The money was for a public school in Baton Rouge that saw its population doubled in the first week of the school year (the hurricane hit on August 28) and had no funding for the additional required supplies. To this day, I am told what an eye-opener that talk was and that the story was in essence so simple that it was hard to believe nothing was ever done to mitigate the situation. Nice. Thank you. That was 9 years ago.

Is Louisiana exceptional in this respect? As a global society, we haven’t been willing or able to reduce green house gas emissions one bit, never mind overwhelming evidence that we must, if only for being at a serious risk of losing exponentially more land than is being lost in Louisiana. I can run off a list as long as my arm with examples of environmental hazards and disasters waiting to happen and elected decision-makers (aka politicians) sitting on their hands. Maybe it’s the weakness of democratic society or the general tendency of the public to stick its head in the sand and elect officials who are good at that too. Louisiana or the world, we will all still be discussing mitigation efforts when the water is at our lips.

ACordal

“Politicians discussing Global Warming”. Installation by Spanish artist Isaac Cordal (Berlin, Germany)

 

 

 

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Canadian Earth Science for @PMHarper 8 – Earth in the firing range

The preamble to this review series is here. All reviews in this series are categorized as “Canadian Earth Science for @PMHarper” (see right hand column).

Spray, J.G. and L.M. Thompson, 2008, Constraints on central uplift structure from the Manicouagan impact crater. Meteoritics and Planetary Science, v. 43, no. 12, p. 2049-2057.

The people of Chelyabinsk didn’t see it coming. And we only know what it looked like because many Russians are in the habit of running dashboard cameras (dashcams): a flash, a loud detonation, shattered windows, 1500 panicky injured people (mostly because of flying glass). No casualties, thank goodness.  The Chelyabinsk meteor was about 20 m in diameter and could have done a lot more damage had it come down a few kilometers to the Northeast in the middle of the city of Chelyabinsk. Mustn’t think of it.

Less than two weeks after the Chelyabinsk meteor came down, Canada launched a ‘suitcase-sized’ satellite to track asteroids and space debris. That timing was completely coincidental of course. The main reason that launch got lots of media attention was the recent near-disaster in Chelyabinsk (a good write-up about the difference between meteors and asteroids is here).

Chelyabinsk crater in frozen lake

The last bit of the Chelyabinsk meteor came down on February 15, 2013 in the middle of solidly frozen Chebarkul Lake (image source). 

The dinosaurs didn’t see it coming either, at least we presume they didn’t. The asteroid that hit Earth 65.5 million years ago on the Yucatan Peninsula was ca. 10 km in diameter. Most likely this hit was the main cause of the extinction of most – large – reptiles (such as dinosaurs), making room – eventually – for mammals, including ourselves. The idea (hypothesis) that a large asteroid could have hit earth and caused this particular mass extinction was introduced only in 1980, when it was considered utterly bizarre even by most experts. Like many utterly bizarre ideas, it proved to be pretty good, especially when the Chicxulub crater was actually found – and proved to be of the right age – 12 years later after the original hypothesis was formulated.

Chicxulub278

The Chixculub (meaning ‘tail of the devil’) asteroid hit in what is now the Yucatan Peninsula of Mexico, but Yucatan didn’t exist 65 million years ago: this was all ocean (image source is here). 

The Manicouagan crater in our own Québec is a lot older than Chixculub: 214 million years. Known also as “the eye of Québec”, it became instantly recognizable as an impact crater after flooding of the Manicouagan river by Hydro Québec in the 1960’s. Now anyone can see it on Google Earth and many astronauts, including Canada’s own Chris Hadfield, have photographed it.

Manicouagan is the fourth largest impact structure on earth. No tectonic forces have influenced or altered it since its inception. The asteroid hit nearly 1 billion year old Canadian shield rocks. After this event, not much else happened geologically, other than the normal amount of erosion, but it never was an area with high mountains so that wasn’t a whole lot. Then the ice caps of the Quaternary glaciations swept across it, nicely cleaning off debris and making it even more easily visible, so it’s a a rather pure and unchanged impact crater.

Manicouagan crater google earth

The Manicouagan reservoir, highlighting the Manicouagan impact structure. 

184 confirmed impact structures pock mark our planet according to the Earth Impact Database, maintained at the University of New Brunswick’s Department of Earth Sciences, also the home base of John Spray, first author of the article under review here. The world’s oldest known impact crater is the 2.4 billion years old Suavjärvi in Russia. Very close to that one in age is the Vredefort crater in South Africa (2.023 billion years old), which is also the world’s largest at 160 km diameter and is – after all this time – easily recognizable on Google Earth and from space. There were likely lots and lots more asteroid hits during earth’s 4 billion year history, but because the earth’s crust is constantly recycled by plate tectonics, we will never know about them (there is no plate tectonics on the Moon, therefore we can see every crater it ever had).

Why study the geology of asteroid impact structures? These structures are studied because, other than for pure scientific curiosity, they host important minerals in large concentrations in a manner that is unique for impact structures. The city of Sudbury marks Canada’s most productive impact structure: it hosts one of the world’s largest nickel deposits . The Sudbury bolide had a diameter of 10 to 15 km and came down 1.8 billion years ago. Everyone knows that Sudbury is the metal capital of Canada, celebrated by their ‘big nickel’. Nickel is an essential mineral for hardening stainless steel.

So what happens when an asteroid hits earth? It depends on the size of the asteroid, so here we’ll limit ourselves to the ones that leave a crater of at least 3 km in diameter. Here is an excellent animation

impact animation

Animation of an asteroid impact (GIF source here)

The animation shows that such a big impact results in:

  1. a field of ejecta (thrown about bits and chunks) outside the crater itself
  2. a crater with faults around the perimeter (where loosened bedrock slid back down),
  3. a melt sheet overlying the original bedrock in the crater; the original bedrock is usually also fractured and altered by the high temperatures (the nickel in the Sudbury impact structure became concentrated at the base of the impact melt sheet).
  4. a distinct central uplift in the crater

The Manicouagan structure has all the features of large impact craters.

Manicouagan seen from East from the road from Google Earth

Manicouagan impact crater seen from the East. The reservoir is in the foreground, the central crater uplift (Mount Babel) is in the background. Panoramio image from Google Earth

The central uplift of the crater is what we now call Mount Babel. Mount Babel’s rocks consist of 1 billion year old basement rocks (gneisses) that were not affected by the asteroid. If you go to Google Earth, search for Mount Babel and tilt the image, you can easily see the central crater uplift that gives this mountain its name.

The article by Spray and Thomson focuses on new details about Manicouagan’s subsurface, revealed through the study of cores obtained by a mineral exploration company. What was learned?

Manicouagan cross section

Above: Geologic map of the central part of the Manicouagan impact structure. Below: geologic cross section b (location on map above). Figure from the article by Spray and Thomson

The study revealed that the Manicouagan melt sheet has a variable morphology and is in places up to 1 km thick! This was a lot more than was originally estimated. Because the drill cores extended beneath the melt sheet, the researchers could observe that the basement rocks underlying it do show evidence of the impact – they have ‘shocked’ characteristics, meaning that the impact changed the nature of some of the minerals that make up these rocks.

The geologic cross sections show that there are faults alongside the crater (as expected). But these faults do not breach the melt sheet, from which the authors conclude that they were active before the melt sheet solidified. It’s possible that these faults run along lines of pre-existing (more than 1 billion year old) faults, but this cannot be proven. The faults are most likely a combination of re-activated pre-existing faults and faults newly created by the impact and occurred within 1000 years after the impact.

The longest core (M5) shows that the melt sheet isn’t uniform: it consists of three distinct layers of igneous rock (solidified melt) of subtly varying composition. Thus: as the melt sheet slowly cooled and hardened, different minerals settled at different depths according to their density: the melt sheet was fractionated, after it had been very well mixed and homogenized prior to it beginning to cool and solidify. Imagine that: an object of 5-10 km diameter hits very hard very old Canadian shield rock and instantly completely melts that rock as far down as 1 kilometer below the earth’s surface. Manicouagan is now only the second impact crater known to exhibit such fractionation (the other one is Morokweng in South Africa).

So yes, while the impact and the melting was instantaneous, faulting lasted much longer, although still pretty much instantaneous from a geologic time perspective.

The authors used all this information to try to figure out how exactly the central uplift structure originated. They present four different dynamic models but their information doesn’t allow them to decide which dynamics led to the structure’s features, leaving room for more research.

Manicouagan melt sheet from Google Earth

The Manicouagan melt sheet up close. Panoramio image from Google Earth

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Earth is in the firing range and it’s important that we study the projectiles aimed at us in order to possibly mitigate a global catastrophe. But it’s also important to study existing impact structures in order to improve our understanding of critically important mineral occurrences associated with these structures.

And finally: whereas the 10 km diameter Chixculub asteroid was mostly likely the cause of the mass extinction that marks the end of the Cretaceous era (the era of reptiles, i.e. the dinosaurs), the 5-10 km large Manicouagan asteroid didn’t cause a mass extinction. Why? That is a topic for a different blog post.

References

Popova, O.P. et al., 2013, Chelyabinsk Airburst, Damage Assessment, Meteorite Recovery, and Characterization. Science, V. 342 no. 6162, pp. 1069-1073. DOI: 10.1126/science.1242642

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#Women in (Earth)Science: Dr. Lui-Heung Chan (@FindingAda)

LuiHeungChan

It’s 30 years ago this Fall that I registered for ‘Chemical Oceanography’, a graduate level class at Louisiana State University as part of my PhD program in Marine Sciences.

The class was taught by Dr. Lui-Heung Chan, a quiet woman whom I had never spoken to before. I had just seen her around the department, dashing in and out of her lab, always dressed in a white lab coat.

Our textbook was “Tracers in the Sea” by Wallace Broecker and Tsung-Hung Peng, published just 2 years before. It became a legendary text, although it was never published again (maybe there were more print runs, I don’t know). It was the craziest textbook you ever saw, because it was essentially a (hard-bound) typewritten document: 702 pages in courier font! It looked absolutely archaic even then. Little did we know that this was going to be one of the great oceanography classics. “Tracers in the Sea” was published by Columbia University’s Lamont Doherty Geological Observatory (where Dr. Broecker works to this day) and LDGO (or, as it states on the book: “Eldigio Press”) has made the entire book available on their website (downloadable pdf).

Tracers in the Sea

At the time, I had no idea that Dr. Chan had done crucially important work on Barium data from the Atlantic GEOSECS* (Geochemical Ocean Section Study) expedition. Her 1977 article on this subject has been cited more than 200 times according to Google (probably a conservative number). The results from the GEOSECS expeditions form the basis of “Tracers in the Sea”.

The class proved to be one of the most challenging I ever took. Dr. Chan meticulously and patiently guided us through every chapter of “Tracers in the Sea”. Thus I became familiar with the data behind the ‘global conveyor belt’ (the global thermohaline circulation), a term coined only a few years earlier by Dr. Broecker, who was one of the initiators of the GEOSECS expeditions (Read all about them here).

Geosecs expedition sampling stations    Conveyor_belt  Left: Sampling stations of the GEOSECS expeditions. Right: “Global conveyor belt” , i.e. global thermohaline circulation 

There were problems to solve with every chapter, assignments, a rather serious term paper and two tough exams. Throughout the class, Lui Chan remained friendly, soft-spoken, and….. tough. I think she was so brilliant that she could hardly imagine we had reason to struggle with the material.

In her quiet way, she impressed upon us what she thought good science was. Good science resulted in simple and elegant solutions and ideas. A scientist should wait with publishing until he/she had enough data to come up with a meaningful story. When discussing a particular isotope, she distributed an article that had recently been published in the journal Science. She mentioned that the researcher had not published anything in a few years before this important paper and she thought that was the way to do it.

“Chemical oceanography” was an eye-opener, probably the best class I ever took. I asked my advisor if Dr. Chan could serve on my committee and he agreed. After all, I had a bunch of radiocarbon dates. She asked me some really tough questions about those at my defense two years later, leading to a few sleepless nights on how to phrase my conclusions so that she would accept them (I managed, she did accept them).

Lui-Heung Chan was born in Hong Kong in 1939. She left for the United States in 1961, completing her PhD at Harvard in 1966. She married Lei-Him Chan, a Harvard PhD physicist. They both got faculty positions at Louisiana State University, he in the physics department and she in the department of geology and geophysics. They had two children.

She was the first woman to become a tenured geology professor at LSU (subsequently in the Charles Jones endowed chair in geology and geophysics). Her most important contributions were made in understanding Lithium in the earth’s crust and oceans. She was a role model for women in science. Sadly, she died after suffering a stroke in 2007. She was 68.

References

In Memoriam http://issuu.com/slebl23/docs/alumnimagazine2006_2007

Chan, L.H., D. Drummon, J.M. Edmond and B. Grant, 1977, On the Barium data from the Atlantic GEOSECS expedition. Deep Sea Research V. 24, p. 613-649. 

Chan, L.H., J. Lassiter, E.H. Hauri, S.R. Hart, J. Blusztajn, 2009, Lithium isotope systematics of lavas from the Cook–Austral Islands: Constraints on the origin of HIMU mantle. Earth and Planetary Science Letters, v. 277, no. 3-4, p. 433-442.

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* The GEOSECS Program was conceived in 1967 and began at the start of the International Decade of Ocean Exploration in 1970. The objective of the program was “the study of the geochemical properties of the ocean with respect to large-scale circulations problems.” We know very little about the oceans today, 45 years after the start of GEOSECS, but we knew absolutely nothing back then and technology was nowhere. GEOSECS yielded massive new insights in ocean circulation and chemistry and provided the basis for understanding the link between oceans, atmosphere and climate.

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And then there were two: Global #Geoparks in Canada

“A what? “

“A Global Geopark”

“Okay, I give up”

Most of you have no idea what a Global Geopark is. That’s not surprising, because – according to my WordPress statistics – most of you are located in Canada and the United States and there are only two (2!) Global Geoparks in these two countries, both of them in Canada: Stonehammer Geopark in the Saint John (New Brunswick) area (enlisted in 2009) and – as of this week! – Tumbler Ridge Geopark in British Columbia. I wrote about Stonehammer in an earlier post as well and I have just added Tumbler Ridge to that post.

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St Martin’s (New Brunswick), one of the sites of the Stonehammer Geopark. Left: drawing by Sam, a grade 2 student from an elementary school in Saint John. The students welcomed the delegates to the Global Geoparks Conference with songs and gave us artwork inspired by the different Stonehammer sites. Right: my own photo of St Martin’s

There are about 115 Global Geoparks in the world, most of them in Europe and the Far East (predominantly in China and Japan). There isn’t a single Global Geopark in Africa, Australia, New Zealand or the Pacific and there are only two in all of South America. If that seems lopsided, it probably is, but it does explain why most people in North America are clueless about them.

So what exactly is a Geopark?

Let’s first explain what it is not: a Geopark is not a Park in the traditional (North American) definition of the word, i.e. a well defined area set aside for whatever recreational or conservation purposes under the authority of a government body.

Then what on earth is it?

The following is from the Guidelines for Canadian Geoparks:

“A Geopark is an area with significant geologic heritage elements, which may include:

  • Scientifically important or striking and unusual geologic phenomena
  • Sites where historically important geologic features were first recognized and described
  • Outstanding examples of geologic features and landforms
  • Historic sites where cultural events were tied to an area’s geologic features, such as those in the history of geology, mining and geology in early exploration and settlement.

The overall goal of a Geopark is to integrate the preservation of significant examples of geological heritage within a strategy for regional sustainable socio-economic and cultural development, while safeguarding the environment”.

Right – you can’t just declare an area a geopark, there has to be a strategy for development and that strategy has to be environmentally-friendly and sustainable. So the challenge is to integrate geologic heritage with regional economic development and ‘greenness’.

Geologic heritage is just about everywhere around us, but most citizens are only minimally aware of that heritage and that is precisely the point of a Geopark: raise awareness of geoheritage with local citizens (K-12 and beyond) as well as visitors. Protect the environment, while providing incentives for local business, especially tourism-related business.

So a Geopark is not a fenced-off hands-off area. On the contrary: it’s a no-fence hands-on area where local business operators cooperate to promote geoheritage through a series of fun and educational activities for all ages. This cooperative effort is independently managed by a board, composed of citizens representative of that Geopark community.

You might argue: that’s an interesting idea, but why do we need this whole new category called Geoparks? Aren’t there enough regular opportunities to celebrate geoheritage?

Good point – there are lots of opportunities to celebrate geoheritage and we’re reasonably good at it in Canada (see my earlier post on the Canadian geoheritage surge here).

But what makes Geoparks special is that this has become a global movement. The thought behind the original idea (launched ca. 20 years ago by an earth scientist-staffer at UNESCO headquarters in Paris) was that the world has lots of valuable Geoheritage that doesn’t qualify as UNESCO World Heritage and that most of that Geoheritage tends to get ignored by the world’s various park organizations, which overwhelmingly focus on living nature and archaeology without paying too much attention to the deep-time-origin of much of that living nature.

How do we define Geoheritage? Geoheritage is the physical evidence of:

  • the origin and history of our planet and the changes it went through (including astonishing and bizarre climatic changes)
  • when and where life on earth began and came from (evolution as shown by the fossil record)
  • the role of our planet in providing us with resources (you are likely reading this on a screen, powered by electricity from the grid – any idea where those materials came from?)
  • the manner in which our planet bubbles and moves and puts vulnerable citizens at risk.

National boundaries are irrelevant for understanding Geoheritage: hence a global movement. And did the idea ever take off. Twenty years after that original idea, UNESCO is seriously looking into making Global Geoparks an official UNESCO program, which would give it a status like that of World Heritage.

Currently, the Global Geopark movement is a Network of Member Geoparks, the GGN. As the members emphasize: “it’s not just a list, it’s a network”. Member representatives get together in even years for a Global Geopark Conference and they gather for a regional Geopark Conference in Europe and Asia in odd years.

The first time a Global Geopark Conference was held in North America was last week, in Saint John (New Brunswick), the hub of Canada’s first Geopark: Stonehammer. And I got to go!

2014-09-19 09.42.27

And while I knew quite a bit about Geoparks and the Global Geopark Network before I went, I had not anticipated the sheer force of passion that I would meet. This truly is a movement: here are thousands of people worldwide (there were nearly 500 at the Conference) who have found each other in the passion of promoting geoheritage as part of local or regional economic development and they are doing that under a globally recognized umbrella, the Global Geoparks Network.

The people that attend this conference aren’t only representatives of Global Geoparks – there are also representatives of Aspiring Geoparks, some of which are close to being to submit an application, for others it’s still a far-away dream. There were also representatives of UNESCO World Heritage sites, national and regional parks, etc.

It’s impossible to give you an exhaustive review of the conference (which was very well organized by the Saint John Stonehammer-folks), so here are some highlights, which I hope will illustrate what this movement is…. well… moving to.

First of all, there was the opening address by the Canadian Ambassador to UNESCO, Jean-Pierre Blackburn, who praised the Global Geoparks Network for carrying out a mission that is in line with the goals and objectives of UNESCO. His entire speech is here: Address Ambassador Blackburn Geoparks Conf (worth reading!).

Now for my impressions of Geoparks in various parts of the world:

I was impressed by the creativity of the English Riviera Geopark. They were established as a Global Geopark in 2007 and will host the next convention in 2016. This Geopark contains the area of Torbay between the cities of Torquay and Brixham in county Devon in South England. There are no fewer than 32 geosites within this Geopark! Interestingly, one of this Geopark’s initiators is Nick Powe, the proprietor and operator of Kent’s Cavern. So yes, Kent’s Cavern is privately run and Nick is the 5th generation (!) of the same family running this business! If that wasn’t special enough: Kent’s Cavern hosts England’s oldest human remains, dating back to the Neanderthals. The cave system has been subject to intense research for close to two centuries, but you can also host a birthday party or a wedding there.

2014-09-20 18.54.05   2014-09-20 10.25.00

Left: Nick Powe of Kent’s Cavern, one of the sites of the English Riviera Geopark. Right: English Riviera Geopark delegates – they also made music! 

I had a fascinating discussion with Renato Ciminelli, president of the Quadrilatero Ferrifero Geopark, an aspiring Global Geopark  in the State of Minas Gerais, Brazil. Minas Gerais is one of the world’s biggest iron ore producing regions, so there is lots of geology there, providing lots of traditional (mining) employment. But the local people are becoming uncomfortable with the idea that their only employment opportunity is through digging yet another hole in the ground – they need their home to be a living, breathing space and they want to diversify their economy. Enter the Geopark concept, which must be community-driven, bottom-up and non-governmental. Talking about a potential Geopark is giving these communities a vocabulary to express themselves about their future. A Geopark as a social change operator? One of the conference themes was: ‘engaging communities’……

I listened to a passionate talk by Farah Alam, who just completed her MSc in landscape architecture at Ball State University in Indiana (her thesis is here). She is from Hyderabad, and works with the Society to Save Rocks, a Hyderabad-based organization that aims to preserve and protect the spectacular 2.5 billion year old granite formations of the Deccan Plateau. The city of Hyderabad is booming and its glorious Monadnocks are blasted to bits to make way for the city. Farah explored whether establishing a Geopark could help the city grow in a sustainable manner without destroying what is essentially an important part of its cultural identity. She designed an inspiring and innovative interpretation centre and landscaping as part of her thesis requirements.

about-society-rocksThe granite landscape near Hyderabad. 

The conference took place in the well-designed Saint John Trade and Convention Center, which also houses the city’s public library and the New Brunswick Museum. Its geology curator, Dr. Randy Miller, was one of the main drivers behind the Stonehammer Geopark. Adding to the spirit of the week’s most important event in Saint John was an international stone sculpting symposium that took place on the dock side in front of the convention centre.

2014-09-19 15.13.46    2014-09-19 15.15.06

Left: The bio of James Boyd, New Brunswick stone sculptor. Right: the work he created during the week of the Geoparks Convention. 

I was immensely inspired by everything I saw and heard: the Global Geopark concept is an innovative tool for preserving geoheritage in a societal context. This is one of the better ideas ever. I predict that, 20 years from now, we’ll wonder how we ever did without this.

Onward Geoparks!

 

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Canadian Earth Science for @PMHarper – 7: very old warm seas in what is now Nunavut (and why there is a Lead-Zinc ore body there)

The preamble to this review series is here. All reviews in this series are categorized as “Canadian Earth Science for @PMHarper” (see right hand column).

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Turner, E.C., 2009, Mesoproterozoic carbonate systems in the Borden Basin, Nunavut. Canadian Journal of Earth Sciences, v. 46, p. 915-938

near Arctic Bay 2

Figure 1. Borden Peninsula near Arctic Bay. Image Source: Google Earth

Canada has immense mineral resources. The Geological Survey of Canada (GSC), a branch of the Earth Sciences Division of Natural Resources Canada is responsible for most basic geologic mapping north of 60oN (and a lot more); the Provincial and Territorial Geological Surveys do all other basic geologic mapping (plus a lot more).

Why do we need basic geologic mapping? Because a geologic map (analog/digital) is the basis for justifying investments in developing and managing a territory as well as the basis for further fundamental geological research. Whether it is resource development, hazard mitigation, groundwater management, or any other human intervention in the land, a basic understanding of underlying geology is a necessary start.

This article is an outflow of a “North of 60″ geologic mapping project, namely that of the Borden Peninsula of Baffin Island, Nunavut. The peninsula sits at 72-73N and is essentially uninhabited, except for the small community of Arctic Bay.

The area under investigation is about 250 x 50 km large. Is it a priority to do geologic mapping all the way up there? Yes, because this area is rich in mineral resources: there is, or rather was, a Lead-Zinc mine: the Nanisivik mine. It operated from 1976 to 2002. The mine site has been cleaned up since 2007 and the community of Arctic Bay has been left with a mixed blessing (see further ‘Additional information’ below).

Finding natural resources is like a sophisticated treasure hunt: the first findings are the ones that stare you in the face. When those run out, you start scratching your head: would there be more? A better understanding of the different rock formations and their relations is then required. That’s what the original goal of this project was: improving understanding of the geological formations that host these ores.

But if you understand this ore-setting better, you can also improve your understanding of other Lead-Zinc ore bodies in comparable geologic settings elsewhere in the world (e.g. in Nova Scotia): studying comparable geologic sites increases the understanding of comparable (not: the same) mineral occurrences.

The rocks of the Borden Basin are about 1.2 billion (1,200,000,000) years old and the formations under investigation consist largely of limestone and dolostone. Limestone is Calcium Carbonate (CaCO3) and dolostone or dolomite is Calcium Magnesium Carbonate (CaMg(CO3)2).

Limestone can form in inorganically and organically. In the inorganic process, seawater evaporates in warm latitudes and shallow seas. As it evaporates, supersaturated carbonate precipitates around tiny grains of sand and the result are extensive and thick beaches and lagoons made up of ooids. This process has been going on for billions of years and is still going on today: most of the beaches on the Bahamas are made up of ooids.

027-Joulters-Key-From-South-Bahamas 200px-JoultersCayOoids

Figure 2. Ooids. Left: Joulter’s Cay, Bahamas – an extensive, thick carbonate platform made up largely of ooids. Right: ooids under the microscope. Each ooid is less than 2 mm in diameter.

But most marine limestone is formed as a result of biological processes: organisms build calcareous (CaCO3) external skeletons (shells, reef structures) by extracting dissolved carbonate from sea water. However: skeleton-building organisms did not exist 1.2 billion years ago – it would take another 600 million years for the first ones to evolve.

Some algae and bacteria also secrete carbonate, mostly in thin filaments that build on top of each other and look like tree rings when you see them in cross section. Algae and bacteria were pretty much the only living organisms back 1.2 billion years ago and some of these algae still exist today: they are called stromatolites and the most famous place where they occur is Shark Bay in western Australia, a UNESCO World Heritage site.

shark bay    stromatolite modern stromatolite proterozoic

Figure 3: Stromatolites ‘algal mounds’. Left: people looking at stromatolite mounds in Shark Bay, western Australia. Middle: Shark Bay stromatolite cut in half. Right: 1 billion year old stromatolite, looking the same as modern-day Shark Bay stromatolite. 

Earth was very different 1.2 billion years ago. Atmospheric oxygen was about 1% of today’s and the sun only had about 3/4 of its current strength. While scientists are still debating the details of the atmospheric and oceanic conditions of this era, there appears to be enough evidence to suggest that earth was relatively warm and could support lots of primitive life. Plate tectonics, the process of mid-ocean spreading, subduction and continent motion, was working too.

Baffin Island Borden Basin Google Earth and Geol map

Figure 4. Left: Geologic Map of the Borden Peninsula (Turner, 2004a). Right: Google Earth image at approximately the same scale. 

Let’s look at the geologic map of the Borden Peninsula and put a Google Earth image next to it (Figure 4). Stunning! The geologic map displays rock formations oriented in a NW-SE direction. The Google Earth image shows clear NW-SE lineaments. So yes: the structure (a geologic basin) in which these limestones precipitated 1.2 billion years ago is recognizable to the naked eye today.

The lineaments on the satellite image are indicative of the structure, i.e. the basin in which these limestones were laid down. The structure (faults) tell us that the basin was formed in a process called rifting. Because we know that plate tectonics was working then as it is today, you should imagine the environment being somewhat comparable to the Red Sea: a narrow seaway at a relatively low latitude (warm!). The Red Sea too is part of a (rather complex) rift system, lying at the upper extent of the East African Rift.

It gets better (what did we ever do before Google Earth?). Let’s fly to the area of the red arrow on the Google Earth image in figure 1 and drop our imaginary plane down:

Baffin island flying from SE

Figure 4. Google Earth close-up image of the area at the red arrow in Figure 1. The lineaments on the satellite image represent a distinct valley through which a river runs, building a small delta into Milne Inlet. 

There you go: the relief we see today on far away Borden Peninsula reflects the remainder of the relief of 1.2 billion years ago. Pretty amazing.

During rifting, heat rises upwards from the earth’s mantle, forcing the earth’s crust to thin and sag, forming a rift basin. The floor and sides of the basin continue to experience high heat flow until rifting stops. When rifting stops, the basin stops opening and subsiding because heat flow was the engine for the rifting process.

The rising heat brings magmas closer to the earth surface as well. Such magmas contain all kinds of trace elements, including metals. In the Borden Basin, cracks (faults) in the rifting basin allowed for focused release of hot chemically charged plumes, which precipitated as mounds, surrounded by some filament-building algae. These mounds are where the Lead-Zinc complex is found today.

In short: in the shallow areas of this basin, extensive Bahama-bank like ooid shoals and beaches kept piling up as the basin floor subsided; in the deeper parts of the basin, concentrated heat flow caused mounds to build-up, incorporating metals and other trace elements.

So the immediate relevance of this mapping project was to locate and understand the ore-hosting formations. As a result, earlier named geologic rock units got renamed. Three new formation names were introduced and they all have Inuktituk names: The Ikparjuk (meaning ‘pocket’) Formation contains the isolated carbonate mounds that are the host of the Lead-Zinc complex. The other new Formation names are the Nanisivik (meaning ‘place where people find things’) and Angmaat (meaning ‘flints’) Formations.

The results of this project contributed to a better understanding of the Nanisevik Lead-Zinc ore body. In addition, much was learned about the ocean-atmosphere conditions during a very old and poorly known period in earth history: a practical question led to much fundamental knowledge that can be applied to other, comparable, geological problems.

This was an important paper: it became the most cited 2009 paper in the Canadian Journal of Earth Sciences.

Additional information on the Nanisivik mine:

The Nanisivik mine produced Lead (Pb) and Zinc (Zn).

  • Lead: The global demand for Lead is still rising, despite the fact that the applications for toxic Lead are decreasing thanks to invention of substitutes. There is still significant demand for Lead in Lead-acid batteries. Read more about Lead here.
  • Zinc: the following is from the USGS minerals database: about 3/4 of all zinc used globally is applied to galvanizing metal. The remaining 1/4 is consumed as zinc compounds mainly by rubber, chemical, paint, and agricultural industries.  Zinc is also a necessary element for proper growth and development of humans, animals, and plants; it is the second most common trace metal, after iron, naturally found in the human body.

The Nanisivik mine had its own Arctic Port, which the Canadian Department of National Defence (DND) intended to upgrade and use as an Arctic fueling port.  Significant ground instabilities appear to wreak havoc with those plans.

A 2002 report on the mixed-success legacy of the Nanisivik mine on the community of Arctic Bay can be downloaded here.

References

Hahn, K and E.C. Turner, 2013, Mesoproterozoic deep-water carbonate mound lithofacies, Borden Basin, Nunavut. Geological Survey of Canada, Current Research, 2013-11, 17 p.

Turner, E.C. 2003a. New contributions to the stratigraphy of the Mesoproterozoic Society Cliffs Formation, northern Baffin Island, Nunavut. In Current research. Geological Survey of Canada, 2003-B2.

Turner, E.C. 2003b. Lead-zinc showings associated with debrites shed from synsedimentary faults, Mesoproterozoic Society Cliffs Formation, northern Baffin Island, Nunavut. In Current research. Geological Survey of Canada, 2003-B2.

Turner, E.C. 2004a. Origin of basinal carbonate laminites of the Mesoproterozoic Society Cliffs formation (Borden Basin, Nunavut), and implications for base-metal mineralisation. In Current research. Geological Survey of Canada, 2004-B2.

Turner, E.C. 2004b. Stratigraphy of the Mesoproterozoic Society Cliffs Formation (Borden Basin, Nunavut): correlation between northwestern and southeastern areas of the Milne Inlet Graben. In Current research. Geological Survey of Canada, 2004-B3.

Turner, E.C. 2004c. Kilometre-scale carbonate mounds in basinal strata: implications for base-metal mineralisation in the Mesoproterozoic Arctic Bay and Society Cliffs formations, Borden Basin, Nunavut. In Current research. Geological Survey of Canada, 2004-B4.

Turner, E.C., and Long, D.G.F. 2008. Basin architecture and syndepositional fault activity during deposition of the Neoproterozoic Mackenzie Mountains Supergroup, N.WT., Canada. Canadian Journal of Earth Sciences 45: 1159–1184.

Posted in Canadian Earth Science for @PMHarper, General geoscience | Tagged , , , , , , , , , , , , , , | Leave a comment

Granites, Glaciers and the Ocean: a hike

We hiked, the other day – a well-known coastal trail, but new to me. So much still to discover here and it’s not like we haven’t been trying. The trail is in Crystal Crescent Beach Provincial Park and takes the hiker all the way around the Pennant Point peninsula in about 4 hours.

Pennant point from Google Earth

Location of the Pennant Point peninsula, which sits as a veritable appendix off the Halifax peninsula. Inset: detail showing the tip of the peninsula (Pennant Point itself). Meaning of red star discussed below. Both images Google Earth

It’s an extraordinary beautiful area and wonderful for hiking as it hardly ever gets too hot or buggy thanks to ocean breezes and fog.  The rocks and the landscape tell a fascinating story. It’s really too bad that there isn’t a single interpretive panel at the trail head.

The peninsula is exposed in striking almost-white granites and granodiorites (igneous rocks). They are peraluminous, meaning that their proportion of Aluminum oxide is relatively high compared to other granitic rocks. These granites are part of a large intrusive body, called the South Mountain Batholith. A batholith is a rock body that solidified from a molten magma as it cooled and moved upward towards the earth’s surface. A batholith consists therefore always of igneous rock and most batholiths are members of the granite family. Because of the excess Aluminum, peraluminous granites look very white, hence ‘leuco’ (meaning ‘light’).

SMB simplified

Simplified map showing the extent of the South Mountain Batholith in Nova Scotia. Black arrow points to Pennant Point Peninsula. Total length of Nova Scotia is about 550 km. 

The South Mountain Batholith rose and cooled in the Devonian, ca. 375 million years ago, a result of colliding continental fragments that pushed the Appalachian mountains upward. The batholith would still have been deep below the surface at that time, overlain by other rocks that formed significant relief, possibly up to 2000 m (Nova Scotia’s southern mainland is barely higher than 200 m today). These subsequently eroded away, exposing these beautiful granites.

The official geologic map of Nova Scotia shows that there are two types of granites here but these are indistinguishable to the casual observer:

Peninsula geology

Detail of official geologic map of Nova Scotia (MacDonald, 2001). The southern part of the Pennant Point peninsula is exposed in Monzogranites (legend M-L Dbmg), subtly different from the leucomonzogranites (M-L Dlmg) of the northern part of the peninsula, which are the same as those at iconic Peggy’s Cove

Another striking characteristic of the granites of the South Mountain Batholith is that they contain lots of xenoliths. A xenolith is – literally – a ‘foreign stone’ (ancient Greek), a rock fragment torn from the rocks that surrounded the magma body as it rose, cooled, and solidified. Because that surrounding rock formation may have eroded away after emplacement of the batholith, xenoliths provide key clues about the area’s geologic history. Xenoliths can range in size from millimeters to tens of meters, as in Portugese Cove, a few kilometers northeast of Pennant Point

photo

Xenolith (dark spherical rock fragment) in Pennant point granites. The white, somewhat aligned flecks are aluminum-rich feldspars that give the granite its distinctive light (‘leuco’) colour. 

The South Mountain Batholith became exposed to the surface the several million years ago, so that it became subjected to the forces of Pleistocene glaciations. Several directions of ice movements are detected along these shores, but, in general, the ice moved away from ice domes situated over major land masses towards the sea (which stood on average 100 m below that of today). The ice caps, a kilometer or more in thickness, had tremendous erosive power. They smoothed the rock surface, and rock fragments that scraped the rock at the base of the ice cap left long grooves in the granite, indicative of the direction of ice flow.

pennant point highlighted striae

Granite outcrop at Pennant Point with glacial grooves (called ‘striae’) indicating the direction of the ice flow (look close: they are parallel to the added red line). The ice cap both smoothed and scratched the rock surface

When the ice melted away, many of rocks that were incorporated in the ice flows, were left stranded. These are called ‘erratics’. While most erratics in this area consist of the same granite as the outcrop, erratics may have traveled hundreds of kilometers, thus leaving important clues for reconstructing the origin and direction of Pleistocene ice flows.

photo 17

Glacially smoothed granite surface with glacial erratics (same granites) at Pennant Point.

photo 1

Along the eastern side of the Pennant Peninsula

Then came the people

Sadly but not surprisingly, we found an immense amount of sea-borne trash on our hike. Other than the usual macerated lobster traps, buoys, gasoline cans and fishing lines, the most impressive piece was a massive 30ft piece of a wharf that rested at the red star at the top of the lake in the Google Earth image, nearly 100 m from the water edge. There was a lot of other trash around the perimeter of the little lake in the image (a.o. a Canadian Coast Guard buoy that was spilling styrofoam mini-pellets), but this was definitely the biggest piece. The assembly of trash and their location clearly shows that this lake and its boulder-rubble seaward edge is a classic storm washover feature, created by repeated battering and overwash from massive storms and hurricanes. Somewhere is a community with a big repair bill. Everywhere are all of us, “planet earth astronauts” (thank you Chris Hadfield) with an even bigger repair bill: that of the maintenance and repair of our fragile and only home.

wharf blown in at Pennant Point   Pennant point itself

30 ft piece of a wharf, resting at the red star in the Google Earth image. Red dashed line indicates washover feature. Other washovers can be seen on the left (W) side of the point. Red star is nearly 100 m from the sea  

 

References

Clarke, D.B. and S. Carruzzo, 2007, Assimilation of country-rock ilmenite and rutile in the South Mountain Batholith, Nova Scotia, Canada.  The Canadian Mineralogist, v. 45, pp. 31-42.

MacDonald, M.A., 2001, Geology of the South Mountain Batholith, southwestern Nova Scotia. Nova Scotia Department of Natural Resources, Open File Report ME 2001-2

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The graphic artist M.C. Escher and his connections with geology

Mobula Rays by Eduardo Lopez Negrete National Geographic    E41-MC-Escher-No-41-Two-Fish-1941

Left: Mobula Rays off Baja California by Eduardo Lopez Negrete / National Geographic. Right: “Two Fish” by M.C. Escher, 1941 from Escher official website

The left-hand photograph circulated on Twitter a few weeks ago and someone commented that “it looks Escheresque”. I found that fascinating: an apparently random natural phenomenon reminded someone of the mathematically composed artwork of the great M.C. Escher.

But of course we know that there is a lot less that is “random” in the natural world than we thought there was roughly half a century ago. M.C. Escher (1898-1972) died before Mandelbrot published his work on fractal mathematics in 1979. Mandelbrot demonstrated that much of the apparent randomness that we observe in nature is the result of relatively simple mathematical relations, controlled by what’s called a ‘strange attractor’. The best treaty on fractal mathematics and chaos theory for non-mathematicians is James Gleick’s ‘Chaos’. I read ‘Chaos’ more than 20 years ago and it completely changed my view on my work, my career and subsequently my life.

For many centuries before Mandelbrot people wondered “only” about symmetry in nature. Everyone observes symmetry and its exceptions, beginning with our own body which appears symmetrical but isn’t: two legs, arms, eyes, ears, lungs, kidneys but one mouth, esophagus, heart, liver, spleen, pancreas, bladder.

The foundations of crystallography and mineralogy are mandatory in every geoscience degree. We learn about molecular lattice structures and resulting crystal form. Depending on molecular lattice structure and resulting crystal structure, some minerals appear perfectly symmetrical, such as a cubic pyrite. At the other extreme is e.g. triclinic plagioclase, which is symmetrical in a more complex way.

pyrite   Albite_-_Crete_(Kriti)_Island,_Greece

Left: cubic pyrite. Right: triclinic plagioclase. (Wikimedia)

Maurits Cornelis (“Mauk”) Escher was fascinated, or maybe obsessed by ‘the systematic compartimentalization of space’ (in Dutch: “regelmatige vlakverdeling” as he wrote in a letter to his nephew Rudolf, a composer).

Mauk’s half brother was Berend Escher (1885-1967), an iconic professor of geology at Leiden University in the Netherlands, whose specialization was crystallography, mineralogy and vulcanology. Berend Escher was also the sole author of the next-to-last Dutch-language introductory geology textbook. The annual MSc-thesis prize, awarded by the Royal Netherlands Geological and Mining Society is named in his honour (full disclosure: I initiated the prize and was chair of its first jury but I didn’t name it).

photo 1

‘Grondslagen der Algemene Geologie’ (Foundations of Introductory geology) by B.G. Escher, 1948 (my copy).

Berend Escher’s textbook doesn’t contain a chapter on crystallography nor one on mineralogy. As an expert in that field, he decided that this subject was too big for just a few chapters in a textbook and in 1950 he published a separate textbook entitled: “Algemene mineralogie en kristallografie” (“Introductory mineralogy and crystallography”). I don’t have a copy of that book nor have I ever seen it.

Did Berend and Mauk exchange thoughts on crystallography and mineral structure? I bet they did. I bet they wrote letters to each other, but if they did, I don’t know about them. We do know that Mauk was a letter writer, because I have a fascinating book with a collection of letters between Mauk and his nephew (Berend’s son) Rudolf Escher, a composer.

Escher 2

Rudolf Escher and M.C. Escher “Beweging en metamorfosen, een briefwisseling” (‘movement and metamorphosis, an exchange of letters). 1985 - my copy

Mauk designed an ‘ex libris’ book stamp for his brother Berend, paying homage to his expertise on vulcanoes.

Escher woodcut volcano for Berend

Mauk Escher explored symmetry in an illusionary manner his whole artistic life. This is not a treatise on that subject, which is too big for one blog post. I include only one illustration here. It is highlighted in “From 2D to 3D: I. Escher drawings crystallography, crystal chemistry and crystal defects” by Peter R. Buseck of Arizona State University, a downloadable 12-page document. Peter Buseck used Escher’s images to teach about symmetry by designing puzzles about them. Here’s one

Escher BrYeBlfishes fishes and lattice lattice 1

Left: M.C. Escher, 1942, Pattern #55 “Fish”. Centre: with lines indicating symmetry (drawn by me). Right: symmetry lines only, immediately showing 3-dimensionality.

I took crystallography and mineralogy at Groningen University in the Netherlands from professor Perdok, who impressed on us (among other things) “that a 2-dimensional space cannot be filled by pentagrams except by M.C. Escher”.

Mauk Escher’s oldest George was an engineer and moved to Canada early in his life. He donated his personal collection of his father’s works to the National Gallery of Canada, giving them one of the largest Escher collections in the world. At that occasion, he talked about his father. His two younger sons became geologists, Arthur in France and Jan in Switzerland.

Why do we continue to be so fascinated by Escher? For one thing, I think that it’s because he shows us something that science alone cannot show us in the same manner: beauty, wonder and unpredictability.

Which is why we always need more Art in Science.

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