Monday, 28 September 2009

Friday, 25 September 2009

RADIALARIANS: TIMEKEEPERS OF ANCIENT SEAS

Radiolarian microfossils, tiny, siliceous, single-celled organisms, make for excellent timekeepers. Think of them as the world's smallest clocks. These wee fellows have been living in the world’s oceans for about 600 million years. Because they occur in continuous and well-dated sequences of rock, they act like a yardstick, helping geologists accurately date rock from around the globe.

KENNECOTT TO KUNGA: A FIERY PAST

Located as they are in Canada’s most active earthquake zone, the Queen Charlotte Islands have had their share of shake-ups and scourings. Many of the Islands’ hillsides are scarred by slides. But the rock beneath speaks of an even more violent past.

Very few people know that the rock in the Queen Charlottes holds the key to a catastrophic event from eons ago. We’ve heard tales and seen images of the cataclysmic damage caused by meteriorites smashing into the Earth’s surface.

Until recently, it was a meteorite impact that was blamed for the worldwide Triassic/Jurassic Mass Extinction. This wholesale dying out of species occurred some 200 million years ago. New evidence challenges the meteorite theory. Experts now believe that tectonic forces may have caused hundreds of volcanoes around the world to erupt simultaneously. The subsequent showers of volcanic ash would have altered the composition of the atmosphere dramatically and plunged the world into near total darkness for years until it settled from the sky.

The picture painted of the sun flickering fitfully through inky clouds, paling against the torrents of glowing lava, while everywhere life is smothered, poisoned, or starved, rivals the most apocalyptic imaginings of Hollywood or religion. We know from worldwide evidence that the extinction was dramatic and affected upwards of 70% of the world’s biota.

Perhaps counterintuitively, for one might think of water as a refuge from fire, smoke, and lava, it was marine lifeforms that suffered the most. This is particularly well documented in the rocks of the Queen Charlottes, especially at Kennecott Point and Kunga Island.

Radiolarian microfossils, tiny, siliceous, single-celled microrganisms, tell the tale. In the Upper Triassic rocks, which predate the extinction by about 10 million years, radiolarians are preserved in hundreds of forms. Just above them, in the early Jurassic rock layers laid down about the time of the great die-offs, only a fraction of the previous number of forms are represented. The more recent Jurassic rock shows a rebound of radiolarian diversity, though of course, in different forms, a diversity which continues to flourish and expand in today’s oceans.

Wednesday, 23 September 2009

Monday, 21 September 2009

MEGAFAUNA: EXTINCT GIANTS

Megafauna were part of a cohort of "giant" animals, species of large animals, reptiles, birds and mammals that went extinct during the Pleistocene as our rellies, the homeo sapien sapiens, were spreading out of Africa and southern Asia to populate the globe. Our rise marked the demise of many of the Earth's most interesting beasts. The term, 'megafauna' refers only to those species larger than forty-five kilograms. Many smaller animals who lived along side these giants also disappeared during the Pleistocene, but it is the largest of the lot who get the title and our attention.

While the fossil record shows that most of the megafauna from North and South America, northern Eurasia and Australia went extinct during this time, it is not the case for all large beasts. Blue Whales, hippopotamus and elephants are notable exceptions, surviving into modern times.

Were we to blame? The court is still out, but most scientists agree that we played a small role at least. Larger scale hunting, climate change, and spreading disease have all been fingered as the culprit for the loss, but, like most ancient mysteries, evidence is mixed and the truth is complicated. My vote is that their ultimate demise is a combination of the three.

Wednesday, 16 September 2009

FIRST LIGHT: HAIDA GWAII

The enormous difference between high and low tide in Haida Gwaii – up to twenty three vertical feet – means that twice a day, vast swathes of shellfish are unveiled, free for the taking.

An ancient Haida saying is still often heard today, “When the tide is out, the table is set.”

Archaeological evidence shows that by about five thousand years ago, gathering shellfish replaced hunting and fishing as their primary food source. The shellfish meat was skewered on sticks, smoked and stored for use in winter or for travel.

Tuesday, 15 September 2009

Sunday, 6 September 2009

Friday, 4 September 2009

Tuesday, 1 September 2009