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(October 19, 2000, Gazette)

Geographer traces changes to landscape

Spruce stump, radiocarbon-dated at 1,400 years oldOne line of evidence for lower sea levels around Newfoundland comes from submerged forests. This spruce stump, excavated at low tide near Burgeo, was radiocarbon-dated at 1,400 years old. Trees generally cannot grow in saltwater conditions. Therefore the sea 1,400 years ago must have been at least several metres lower than today.

By Andris Petersens
SPARK Correspondent

What we see today is not the same as what we saw yesterday. Still, the small changes in the environment may pass by our eyes unnoticed and a century from now, everything may look as if we had never been here.

Nevertheless the landscape has changed. To find out more about those changes we have to explore past landscapes. According to Dr. Trevor Bell, Geography, the Newfoundland landscape looked much different 20,000 years ago than it looks today with land covered in ice and the sea floor, such as the Grand Banks, exposed as land.

At that time, most of mainland Canada was covered with a large continental ice sheet while Newfoundland had its own smaller ice cap. As the climate slowly warmed, the ice melted and retreated. Today scientists are interested in the dynamics of ice retreat and climate changes in the past to find out how large ice masses like the Antarctic or Greenland ice sheets might respond to future climate warming.

The growth and decay of ice sheets cause changes in sea level, Dr. Bell explained.

“Sea level changes in Newfoundland are mostly the legacy of the last glaciation. The source of water for these large ice sheets is the oceans. So, as ice sheets grow, ocean volume decreases and sea levels fall everywhere. At high latitudes, however, the weight of the ice sheets cause the Earth’s crust to sink, causing local sea levels around the ice sheet to be higher. Later, as the ice sheet melts, the crust rebounds slowly. My work looks at the pattern, magnitude and timing of these sea level changes around the province.”

One way to document changes in sea level is to examine marine features and sediments that relate to former shorelines and to date fossil shells, driftwood and whalebone found in them.

On the Northern Peninsula, the sea level at the end of the last glaciation was 140-150 metres higher than it is today. Much of the coastal lowlands was below sea level. Gradually, the land has emerged from the sea exposing islands and peninsulas. Meanwhile, for the remainder of the island portion of the province, the sea has been submerging the land, drowning islands and eroding the coastlines. In such places as Stephenville, Port-aux-Basques and Burgeo, the sea has risen 30 metres or so in the last 10,000 years.

Dr. Bell, together with Dr. Joyce MacPherson from the Geography department, explores how the vegetation has changed since the ice sheets retreated.

“It is a succession from pioneer species, to shrubs and then trees, the forest itself evolves as the landscape changes. We use the change in vegetation as a sort of proxy for climate change and other types of environmental change. For instance, our coastal climate is influenced by the Gulf Stream and Labrador Current – the Gulf Stream being warm and the Labrador Current being cold. If you have changes in the strength of those currents, for example, then it may affect the climate, which may in turn influence the vegetation. My graduate student, Nicola MacIllfhinnein, is looking to see whether we can recognize these large-scale environmental or ocean changes in the postglacial vegetation record, using pollen preserved in pond sediments on the Grey Islands, off the Northern Peninsula,” Dr. Bell said.

Dr. Bell also works closely with Dr. Priscilla Renouf, Archaeology, on a collaborative project that started in 1997 when they received a special new initiatives grant from vice-president (research and international relations). This grant allowed them to start the project and apply for NSERC and SSHRC funding.

By integrating cultural history, archeology, paleogeography and sea level history, Drs. Bell and Renouf have located sites of Maritime Archaic Indians, the oldest inhabitants of Newfoundland.

“One of our approaches was to do targeted archaeological survey based on our knowledge of sea level history,” Dr. Bell said.

One of the immediate successes of this collaboration was the discovery of a large site in Port aux Choix. The Northern Peninsula is the only place on the island where sea level has been constantly falling since the ice retreated said Dr. Bell.

“If we are going to find the older shorelines and possibly more Archaic Indian sites, it is going to be on the Northern Peninsula, where the fall archaeological record should be preserved above present sea level. Unfortunately, many of the older shorelines of the peninsula are in the woods, not around the present day coast. It makes field surveys challenging.”

Drs. Bell and Renouf are also interested in how ancient people affected the local vegetation, how they used that vegetation, how they located their sites on the landscape, and what was important to them in selecting a site. In Port aux Choix, the Maritime Archaic Indian cemetery today is on a peninsula in the centre of the town but in the past it was on an island. For 1,000 years, the Archaic Indians probably lived on the mainland while they buried their dead in the cemetery. They were obviously living on a beach that was poorly vegetated. Over time, as they kept coming back to the site, vegetation developed starting with a shrub forest and then eventually a full forest. There may also be evidence of human impact on the vegetation.

“We have found a spruce log dated to the Maritime Archaic period with cuts in it that look as if it has been worked. We have also reconstructed the local vegetation history and at the times when the site was occupied, we see dramatic changes in the vegetation,” Dr. Bell added.

Over the next couple of years, Dr. Bell hopes to extend his work from the west coast of Newfoundland to Labrador, where he will continue to document past changes in our landscape and environment and the history of humans on that landscape.

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