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Published: June 15th 2008
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5.01 A Cliff Face on Seymour Island
The cretaceous-tertiary (KT) boundary slopes from left to right just above the large U-shaped scree accumulation. One morning on the 2008 voyage we awoke to find ourselves anchored within a zodiac's ride of Seymour Island on the east coast of the Antarctic Peninsular. I had long been awaiting this moment because Seymour Island is unique in that the cretaceous/tertiary (KT) boundary, the boundary at 65 million years ago between the end of the age of the dinosaurs and the present age of the mammals, is clearly evident. And not only evident but exposed because it is too cold for plant growth and yet snow- and ice-free, being in the lee of James Ross Island. So our enthusiastic palaeontological guide and presenter on the
ABC's Catalyst program, Paul Willis, had us boarding the zodiacs as the last of the morning fog lifted to reveal a perfect summer's day. As we approached a cliff face we could see the KT boundary sloping downwards from left to right above a U-shaped scree accumulation so we followed the coast to the right and went on shore above the boundary in a tertiary stratum. After we landed we ascended the hill towards where the KT boundary was exposed and on the way saw some fossils of molluscs and even logs from a small
5.02 Fossils from Seymour Island
Some fossils of molluscs from the Tertiary Period. tree. At last we crossed a ridge and on the descent on the far side turned back to see the KT boundary before our eyes. At this place a few boulders were scattered about on almost level ground but behind and just above this was the actual line that marked the extinction of the dinosaurs and then a stratum, about one metre in height, that was slightly paler. Paul thought that this may have been from the period of perhaps 20,000 years in which the earth was virtually sterile because 99.99% of life had been extinguished and there was, therefore, no organic matter there. Higher up, however, the next stratum became slightly darker suggesting that life may have started to recover and deposited some organic matter. Astounding that one event some 65 million years ago could lead to the extinction of the dinosaurs and change the history of life on earth forever! As we were now in a cretaceous stratum we decided to scatter to see if we could find any ammonites from that Period and one of the expeditioners was successful. And better still, Paul's day was made because he found a meteorite that was almost as large as
5.03 Another Fossil from Seymour Island
Another molluscan fossil from the Tertiary Period. Photo by Amanda Till, Assistant Expedition Leader. a football!
Fossils were first discovered on Seymour Island in the 1890's by the Norwegian sealing Captain, Carl Larsen, and this discovery was followed up by the 'Swedish Antarctic Expedition' in 1902-'03. This was led by Otto Nordenskjold, a Swedish geologist, who had already made extensive explorations in Patagonia, Klondike (Alaska) and Greenland and his ship, the
Antarctic, was captained by Carl Larsen. Nordenskjold and five colleagues were stationed at a hut at the northern end of Snow Hill Island, just to the south of Seymour Island, from February 1902 to November 1903 and made extensive explorations and observations in geology, paelaeontology, meteorology and other sciences while there. Their second winter there in 1903 was inadvertent because their ship, unbeknown to them, had been crushed in the pack ice off Paulet Island in February '03. However, they did meet three expeditioners, who had been left at Hope Bay near the tip of the Antarctic Peninsular the previous summer, at Cape Wellmet (northern side of Vega Island) in October '03. Their purpose had been to travel over the ice to tell Nordenskjold that the
Antarctic could not get through the pack ice, but they could not do so because they
5.04 Some Fossilised Logs
These logs were about 12cm in diameter and were from the Tertiary Period. were blocked by open water! Consequently they had over-wintered at Hope Bay and were making a second attempt to get to Nordenskjold's hut in October '03. In the mean time, the remainder of the twenty one crew of the
Antarctic had over-wintered at Paulet Island - one died during this period - and then six of them, including Carl Larsen, had rowed to Hope Bay to find that the three expeditioners that had been dropped there had left. However, they had left a note so Larsen and his five crew members rowed to Nordenskjold's hut and arrived shortly after the five from Cape Wellmet. They were, of course, still isolated without a means of returning to civilisation but a few days later an Argentinean ship arrived to take them back to Buenos Aires.
In spite of these travails the expedition was regarded as a great success and Nordenskjold was feted as a hero in Buenos Aires and Sweden. In the intervening years Nordenskjold's achievements have faded from public view but some scientists did embrace his contributions to palaeontology. So, in the last quarter of the last century palaeontologists - in particular Bill Zinsmeister from Purdue University in Indiana -
5.05 The Cretaceous-Tertiary Boundary
The KT boundary is just above the scattered boulders. About one metre above this is a darker band which is thought to be due to organic matter that had accumulated when, after some 20,000 years, life had recovered from the impact of the meteorite 65 million years ago. started to visit Seymour Island. They now have a detailed geological map and many fossils some of which provide evidence, for example, that a whole series of successive blooms of plankton killed fish and other marine life over about 20,000 years after the impact of the meteorite.
So it was with high expectations that we set off in the afternoon, after visiting Seymour Island, in zodiacs to visit Nordenskjold's hut near the northern tip of Snow Hill Island. But we were to be disappointed in that we were unable to land due to thin pack ice: one can just see the hut to the left of a small iceberg in the accompanying photo. It somehow seemed to reflect Nordenskjold's place in polar exploration: unlike Scott, Shackleton or Mawson, his achievements are not in the public eye.
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