Dear Mr. Carney

That must have been a lovely stay, a “short week” (I’m quoting the Globe and Mail) with your family near the small village of Cheverie on the shores of our beautiful Minas Basin. As a proud constituent of Mr. Brison, I know the location of his house well, as it is the site of his annual constituency BBQ, always a terrific party with great music on that magic spot, the big field on top of the cliff overlooking the basin.

You must have frequently walked down to the beach at the end of the road (maybe you even went for a swim during those 2 hours around high tide) and I hope you took a moment to ponder the unusual sight there of a small outcrop of brilliant white rock shown in this picture with the steeple of the Cheverie church above it: cheverie point at macumber looking from cheverie point

A little closer, it looks almost eerie: TSOP 07 Cheverie anhydrite

This is an outcrop of anhydrite, which is a form of gypsum, if you wish. The gypsum belongs to what geoscientists call the ‘Windsor Group’, an assemblage of limestone, gypsum and salt that crops out (geoscience term for: ‘visible to the human eye without digging or excavating’) in the area around Cheverie. I’m sure you saw these outcrops on your drive to your holiday location. Nova Scotia has a lot of gypsum, an indispensable building material. The gypsum mine between Scott Brison’s house in Cheverie and his constituency office in Wolfville ran for about 80 years until it closed recently, one of the many victims of the global recession. It’s hard to get that gypsum out, as it needs to be shipped out of a basin with the world’s highest tides, hence the time window for ships to come in, load and turn around, is very short. Ingenious process technology was invented to meet those conditions, some of which you can still see at the wharf in Hantsport, but that ingeniousness made the whole process quite expensive, explaining why it recently collapsed.

Gypsum precipitates when seawater evaporates in shallow seas in hot wet climates. The gypsum (or anhydrite, to be correct) near Cheverie precipitated in shallow seas more than 300 million years ago, when what is now Nova Scotia was located more or less at the equator. Yes, we moved up quite a bit! Oddly enough, just below that gypsum are rocks that are full of organic material, even coal. Coal is fossil plant material and becomes preserved in hot wet climates, a situation that is diametrically opposed to the one in which gypsum precipitates. There is not yet a good explanation for this sudden climatic about-face. During hot and wet conditions, wide rivers ran through a lush green landscape, in which thick peat bogs (our future coal) accumulated. It was very fertile ground, where the first amphibians set foot on land in search of abundant food. Right in front of Scott Brison’s house is a surface, representing a fossil river bank, full of indentations that mark the location of of fossil trees: cheverie point tree roots in horton 1  cheverie point tree roots in horton3

Amazing, isn’t it? There are lots more amazing rocks along that same shore. I’m sure you saw the red rocks as well. They are the deposits of wild rivers that ran through a near desert environment in the middle of a gigantic continent. They look rusty red and that’s exactly what explains their colour: rust. The iron in these sediments became oxidized due to exposure to air. There was no sea or ocean anywhere at that time. These rocks are more than 200 million years old and Nova Scotia was located at about 15 degrees North at the time, the same latitude as many of the world’s great deserts now. It was a bleak time in the history of the earth, because the planet had just experienced a massive extinction which did away with 95% of all life. You won’t find a lot of fossils in those rocks, but there is evidence of some of the first dinosaur-like creatures in them. Most of these have been found along the north shore of Minas Basin near Parrsboro (where the lampposts are decorated with dinosaur lights).

And every day when you woke up, you looked across this magnificent basin and saw that big Cape on the horizon. That’s Cape Blomidon, a named that was morphed from ‘Blow Me Down’ (there is a place on the West coast of Newfoundland that also has that name, by the way). You can’t see a lot of detail in Blomidon from Cheverie, but maybe you took a day trip around the basin and visited Blomidon Provincial Park or even hiked Cape Split. I insert a picture of Blomidon here (taken on a very cold overflight one winter to photograph the ice in the basin): 668-6844_IMG

There is solid looking rock on top of Blomidon, very different in colour and texture than the underlying red rocks. The solid looking rock on top of Cape Blomidon is basalt. Basalt is definitely not a sediment. Basalt is extruded from the earth’s interior during times of so-called continent break-up. Pretty much like what happens in East Africa today where the Great Rift Valley marks a tear in the continent. The basalts of Cape Blomidon are about 200 million years old and mark the time when the Atlantic Ocean began to form.

And in between all this is loose sediment that may still become rock some day in the geologic future: the tidal sediments of Minas Basin and its eastern extremity Cobequid Bay, exposed only for a few hours, as shown here: met voetjes. Did you go and watch the tidal bore somewhere? I’m sure you learned about the efforts at generating electric power from in-stream tidal turbines. It’s not going as fast as everyone had hoped, but that’s because nature continues to be a difficult one to work with. I do hope that we’ll manage to harness the tides one day, so that we can run on cleaner energy while maintaining good stewardship of our unique environment. We should be able to do better than previous generations, who logged the place bare and hid the nutrient-giving marshes around the basin behind dikes. They are now a cherished cultural phenomenon, those dikes, but they do wreak havoc with ecosystem balances.

Did you come across a wonderful book called “The last Billion Years” ( in Scott’s library? It tells the story of the geologic history of the Maritimes for the general public. I don’t mean to be disrespectful, you are not an average member of the general public, but you may not have a geosciences background, so I do recommend it highly.

In closing, I hope that you will tell many of your important relations here in Canada and, starting later this year in the UK, about our wondrous, amazing, natural environment which supported our economy, but – in a modern world with different economic drivers – also caused our decline. Raw resources alone are not sufficient to build a long term stable economy, value-added products is what builds a better chance at longer term prosperity. In the near future, we can hopefully capitalize somewhat on our unique geoheritage through the development of geoparks, building on the fame of the Joggins Fossil Cliffs World Heritage Site (

With best wishes for a bright future on the other side of that ocean of which you observed the very beginnings right here on your holiday,


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The tidal landscape banner photo: Minas Basin, Nova Scotia, Canada


UPDATED December 29, 2014

This was my blog’s banner photo until January 1, 2015. What are you looking at? In a world of Google Earth where everyone has a GPS in their cell phone, I should start with the coordinates. You are standing at 450 6’ N, 200 33’ W, and you are looking North.

Minas Basin with banner photo location

Minas Basin, Nova Scotia. The pink trapezoid indicates the view in the banner photo

You are on the south shore of Minas Basin, which is the eastern arm of the Bay of Fundy, and this place has the world’s highest recorded tides: the average tide range (difference between mean high tide and mean low tide) is about 12 m, but it can increase to as much as 16 m.

The basin is about 80 km wide in an E-W direction and about 30 km at its largest N-S extent. It has a semi-diurnal tide (2 highs and 2 lows for each lunar day) and all that water comes in through the narrow Minas Passage. Actual tide charts are at .

Minas Basin is surrounded by cliffs. The cliffs are exposed almost exclusively in soft sedimentary rocks, with the exception of the top of the Cape in the distance, which is exposed in Basalt. The cliffs therefore erode rapidly and new exposures are constant.

So this place is pretty much heaven for a sedimentologist. Which is what I am. I first became truly hooked on (clastic!) sedimentology while doing fieldwork for my Master’s thesis research in the macrotidal estuaries of the southwestern Netherlands, where the tide ranges is “only” about 4.5 m tide range.

This banner photo is pretty much the view from our house, which incorporates my office. I can’t think of living in a more interesting place, given that the people here are also really terrific.

Earth scientists categorize tide ranges as micro-(<2m), meso- (2-4m), macro (4-6m) or  hypertidal (>6m). Minas Basin and only a handful of other estuaries in the world are a category of their own with their extreme tide ranges. The only estuary that bears any comparison to Minas Basin is Knik Arm in Alaska, which has a 10 m average tide range.  Like Nova Scotia, that area was heavily glaciated during the Pleistocene and the glaciers left thick packages of sediments (tills, eskers, drumlines etc.). Also, Knik Arm is routinely covered in winter ice.

Another area of hypertides is is Ungava Bay in northern Quebec, which might actually have a marginally higher tide range than Minas Basin (difficult to measure), but there are no glacial deposits around Ungava Bay, because the area was scraped clean by the ice caps, leaving only bare rock exposed (easy to see on Google Earth). Famous for its extreme tides and tidal bore is the Bristol Channel / Severn estuary, separating South Wales from Dorset and Cornwall. Southern Wales was under ice caps during the maximum Pleistocene ice extent, but the ice didn’t reach across the Bristol Channel. The Gulf stream keeps this part of the world ice free year-round, even though it is at about 52deg N.

The extreme tide range of Minas Basin means that there is virtually no shipping. Too dangerous, the currents are as fast as Usain Bolt when he runs the 100 m dash. There are a couple dozen commercial fishing boats in this basin. Until a few years ago, especially designed vessels transported gypsum out of the basin, but the recession ended the demand for gyprock and the mine is now closed. In summer, we kayak here, though. We use a 2.5 hour time window just before high tide. It makes for interesting adventures.

Few people live here, but the interventions over the centuries have been more significant than you might imagine. About which more some other time.

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Rachel Carson – as relevant today as she was 50 years ago

There is a new biography of Rachel Carson, the author of “Silent Spring”, which was published 50 years ago this year. The biography is by William Souder and is entitled “On a Farther Shore: The Life and Legacy of Rachel Carson”.

Full disclosure: I didn’t read “Silent Spring”. Of course I have been aware of it for as long as I can remember. The book came out in the year I turned 10, but I grew up in the Netherlands and so it took until I was a student in the ’70s to become aware of it. And by that time the book was already iconic, legendary and its thesis generally unquestioned.

I didn’t read the biography either, but I just finished reading a review of it in the New York Review of Books (Tim Flannery, “A heroine in Defense of Nature”, By the way, if you can read only one periodical, then read the NY Review of books, which is about much more than just book reviews.

The most shocking bit of information that I learned from this article is this: in the early 1950’s, Eastman Kodak (in Rochester, NY) discovered streaks on its unexposed X-ray film. It turned out that the cardboard packaging of the film was radioactive. Why? It was produced in Iowa and Indiana by paper mills that used water from mid-western rivers, which were under the influence of radio-active fallout from the Nevada test site……

I am a baby boomer. We were born and lived our early years on a planet that experienced frequent and constant above ground nuclear testing. What that did to our health, nobody knows, because you can’t separate that influence from the influence of other poisons that we were routinely exposed to, such as pesticides, the main subject of Rachel Carson’s “Silent Spring”. Incidentally, it was her publisher who came up with that harrowing title.

Rachel Carson was already a well-known and popular nature writer when she published “Silent Spring”, so there was immediately a lot of attention for her new book. President Kennedy referred to it in a press conference that Fall in answering a question about curtailing the use of pesticides. But the chemical industry went on full attack, calling her subversive, a communist sympathizer, anti-business, a health nut, a pacifist and, predictably, a spinster.

Fast forward to 2012. In terms of pesticide use, the western world has accepted its detrimental effects. Environmental protection measures have improved matters significantly, although it could have been better. But society still struggles with (big) industry’s strong-arm tactics, and certain earth resources industries are not exempt from that behaviour either. Will they be proud of their present-day attitudes 50 years from now?

Rachel Carson felt that she had no choice but to write Silent Spring, quoting Abraham Lincoln: “to sin by silence when they should protest makes cowards of men”.

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A day to celebrate women in Science: Kiek Jelgersma

October 16 is Ada Lovelace day, a day to celebrate inspiring women in science.

What a great opportunity to write about two women geoscientists who I admired and knew.

First I will write about Dr. Saskia Jelgersma, better known as ‘Kiek’ (for Saskia). Kiek passed away in May of this year at age 82. There is an excellent obituary in English of her on the site of the Telegraph: Do read it.

Kiek was a Quaternarist – she worked her entire career on the Quaternary, more specifically on the Holocene, the most recent 10,000 years of Earth history. Hers is the yet to be improved Holocene Sea Level curve of the Netherlands, the result of her PhD dissertation in 1961. To produce a scientific result that stands uncontested for this long is an astonishing accomplishment and points to her drive for perfection.

Kiek was fearless, loud, and – at times – abrasive. She was also loyal to the core, passionate about her science (and about anything else she happened to delve into). I met her a few times and became friendly with her (that wasn’t easy). I think she was the only working female geoscientist in the Netherlands for the first 15 years of her career. And there weren’t very many afterwards, certainly not until she retired (for a few years around 1990, I was one of them).

The Telegraph obituary mentions that she was awarded the ‘Van Waterschoot van der Gracht’ medal of the Royal Netherlands Geological and Mining Society ( in 1997 at a special symposium (organized in her honour), entitled ‘Sea level and Science Fiction’. Yes! That’s true, I was president of KNGMG at the time and I organized that symposium and I had the privilege of presenting her with the medal. It was the first time I wrote a citation speech, and I discovered I loved doing that. Maybe this was the first and only time that Kiek was quiet, subdued, but only for a minute. When I finished reading the citation, she came up to the podium and whispered to me ‘this is a big moment for me, a big moment…’ (in Dutch ‘een groot moment’). To this day, she is the only woman ever awarded this medal, the highest honour of KNGMG.

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