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Gros Morne’s Old Lost Sea

By: | June 14, 2011

The extraordinary, ancient, oceanic landscape that made Gros Morne National Park a UNESCO World Heritage site.

Liam Herringshaw
Old Lost Sea is a natural history of Newfoundland & Labrador.

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Since I started writing this column, I have been pestered by literally nobody as to why it is called Old Lost Sea. Either it is plainly apparent, or no one cares. Whatever the case might be, I feel the need to explain myself now, for fear the rest of this article won’t make much sense.

Firstly, and most stating-the-obviously, Old Lost Sea is an antonym of Newfoundland, reflecting the fact that this place isn’t recent, nor a recent discovery, and isn’t even especially terrestrial. Overlooking my dreadful Latin, it’s as much Mare Vetus as Terra Nova.

Secondly, the title refers to my research interests. I am a marine palaeontologist, and fossils from ancient oceans are my thing; I spend much of my time hunting for life from old, lost seas.

Finally, and most relevantly to this piece, Old Lost Sea refers to Newfoundland’s pivotal role in one of 20th century science’s greatest scientific advances, one which would prove that oceans could disappear completely.

Proving plate tectonics

The theory of plate tectonics still feels revolutionary today.  The idea that the Earth is constantly moving, that continents can collide and mountains can migrate, seems faintly crazy. But we know that they do, and evidence that proved it was unearthed from the rocks of The Rock. Lots of localities yielded data, but the place that provided the key piece in the puzzle was the extra-terrestrial terrain of the Tablelands, in Gros Morne National Park.

This triumvirate was a pre-internet WWW, and though you might not have heard of them, their impact was just as global.

The key players, scientifically, were three geologists: an American, a Canadian, and a Newfoundlander. Named Walcott, Wilson and Williams, this triumvirate was a pre-internet WWW, and though you might not have heard of them, their impact was just as global.

Charles Doolittle Walcott, the American, was a trilobite-tracker extraordinaire. In 1888, he came to Manuel’s River, in Conception Bay, to hunt these early arthropods.  As a consequence of the fossils he found, Walcott was able to show that those of eastern Newfoundland were fundamentally different from those of western Newfoundland.

Most curiously, the trilobites of the Avalon Peninsula were the same species as those found in Wales, England, Ireland and Scandinavia, whilst those of western Newfoundland were like those of Scotland and Greenland.  Walcott plotted out a fossiliferous map, and noted that an almost-straight line divided an ‘Atlantic’ fossil zone from a ‘Pacific’ one.

Why the weird fossil patterns?

What did it mean?  How could the distribution be explained?  Walcott didn’t have the answer, and the best theory that earth scientists could come up with was that there had once been a giant trough separating the different regions.

The man who came up with a rather more scientifically satisfactory solution was Toronto-based geophysicist John Tuzo Wilson. In the 1940s, Wilson began re-examining the line separating Walcott’s fossil provinces, especially in southern Scotland, Scandinavia, and central Newfoundland.

A region where two ancient plates had collided with unimaginable power, crushing and melting the crust.

The rocks of these regions were a mixture of metamorphics, volcanics and deeply cooled magma chambers, mangled and sheared, faulted and fractured. Wilson recognized they were the roots of a mountain belt, of a region where two ancient plates had collided with unimaginable power, crushing and melting the crust.

The reason for Walcott’s weird fossil patterns, Wilson realized, was that eastern and western Newfoundland had once been on different continents.  “Did the Atlantic close then re-open?” he asked in a 1966 paper, one which was as much an answer as a question.

The country and western of Hank Williams

Wilson’s theory was suddenly, unifyingly simple. The “Atlantic” and “Pacific” fossils represented separate marine ecosystems that had existed on separate continental shelves, half a billion years ago.

They had been divided by an old lost sea, which had been gradually consumed as immense forces deep within the Earth dragged the landmasses together.

Wilson called it the proto-Atlantic, but later scientists suggested a more appropriate name: the Iapetus Ocean, for the father of Atlas.

It was amazing, and brilliant, but if it was true, where was the ancient ocean? To take on the mantle of responsibility, enter Wilson’s PhD student and Memorial University alumnus, Hank Williams. With a name like his, it was perhaps inevitable he should love country and western, and Williams certainly adored music. Geologically, however, his country was Newfoundland, and his western was Gros Morne.

More precisely, his western was the Tablelands. For there, where the hills were barren and otherworldly, a sure sign that something odd was afoot, Williams found the Iapetus Ocean.

The Tablelands are barren for a good reason. They aren’t formed of continental crust like the rest of the region’s hills, but of a slab of sea floor.  Composed of iron- and magnesium-rich minerals, oceanic crust is much denser than the quartz-rich continents.  It normally gets pulled under – subducted – when the two collide.

In this way, the east Pacific sea floor is disappearing today beneath continental South America, the collision creating the Andes (and the devastating earthquakes).

Extraordinary rocks

In western Newfoundland, however, when the Iapetus Ocean was being forced under North America, the impact was at an oblique angle. Rather than disappearing entirely, a sliver of Iapetan sea floor rode up over a chunk of continent trapped in the collision zone.

Such oceanic blocks, known as ophiolites – “snake rocks”, referring to their greenish colour and twisted, reptilian layers – are incredibly rare, giving unique glimpses into the make-up of the ocean floor, and the engines of plate tectonics.

Every year, countless scientists from across the globe come to admire.

Williams recognized this, promoting the importance of the Tablelands ophiolite, and, thanks to his efforts, in 1987 Gros Morne was declared a UNESCO World Heritage site. Every year, countless scientists from across the globe come to admire and interrogate the extraordinary rocks.

But though they may be great for earth scientists, the Tablelands aren’t so good for greenery. Unsurprisingly unfamiliar with trying to grow on what was once the deep sea floor, plants find it very difficult to eke out a living on such a substrate. So the barrens remain barren.  And from his unvegetated perch, old Iapetus gets to keep an eye on his upstart son.

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