Marcus James Thomson, Ph.D.

Gaspe winters

My great grandmother was born in a village called Shigawake on the Gaspé, an historic peninsula on the Maritime (Atlantic) coast of Quebec. My family still has a house there. I grew up with stories of the tremendous winter storms that raged when we were away in Upper Canada, and observing the evidence of them on returning during the summers in between. Much of the coastline is dominated by cliffs of Devonian limestone, which erodes easily under the combined stresses of seawater waves, ice and salt crystal formation in cracks; and its submarine relief, falling quickly into deep water, means that wave energy is strongly focused on the shoreline itself.

Images (clockwise from top left): looking east-northeast over Hope Beach; farmhouse in between the villages of Shigawake and Port Daniel; the red cliffs of St. Godfroi.

The video is a piece from CBC News covering some of the damage to the coastline that winter storms have caused of late. The town in the story, Percé, is an hour and a bit east of Shigawake and famous for its great “pierced rock” (Rocher Percé), a landmark on the tourist trail.

It is reasonable to think that this is all a recent development; that the rate of erosion has recently increased, and so on. Proving that over historical time would be relatively easy, say, by comparing old photos, locations of wharf piles, and even 40-some years of satellite images. But doing so with anywhere near the required level of precision over prehistoric time would be tricky. One way would be to investigate marsh or mudflat accretion and development rates. But there are limited places to do this along the coast; and this would tell you more about sea level change than storm intensity and frequency. To understand storm intensity, you could take cores from intertidal mudflats looking for gravel lenses with marine shell fragments. These would be reasonably datable with radiocarbon from the shells and gravel composition would give you some idea of the intensity of the storm surge that produced them.

This entry was published on March 3, 2017 at 10:44 PM and is filed under Uncategorized. Bookmark the permalink. Follow any comments here with the RSS feed for this post.
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