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Page 31 - The Great Aspy Landslide and the Search for Witnesses or Memories

Published by Ronald Caplan on 1995/6/1 (1221 reads)
 

The Great Aspy Landslide and the Search for Witnesses or Memories • by Geologist Doug Grant The Aspy Landslide took place about 1904 • recently enough that there could still be someone living who heard it. Certainly, the event was so enormous that stories must have been told about the sound, about changes in the weather, about the movement of roads or riverbeds. Have you heard any story about the Aspy Landslide? Here's geologist Doug Grant's report of the event. 1994 Cape Breton Highlands plateau area of landslide The largest landslide in the Atlantic Provinces region in historical times apparently oc? curred early in this century when a huge section of the Cape Breton Highlands cliff fell away opposite the farm of A. MacDonald and Sons near Big In? tervale in Aspy Valley. Al? though now largely overgrown, the slide scar is still visible from the Cabot Trail (see photo) as strips of barren rubble showing through new for? est. The area of the slide is 1500 meters wide and extends up the slope to its top at 400 meters elevation. The slumped mate? rial forms a hummocky linear festoon-like ridge with multiple lobes about 1500 me? ters long, 200 meters wide, and 50 meters thick, which covers up part of an old ter? race along the North Aspy River. The volume of the slide is at least 20 million tons. Air photos taken in 1936 show much less forest on the slide scar, so it was estimated that the slide had oc? curred a few decades earlier. To determine the age of the slide, officials of Cape Breton Highlands National Park, not? ably James Bridgland, kindly arranged for a drg 94-10-061;. dendrochronological study in 1992. Done by Randy Power, this involved simply counting the number of rings in the oldest tree at the margin of the slide compared to the nim- ber in the oldest tree which had regrown on? to the slide rubble. This showed that the slide occurred at least 80. and probably closer to 90 years ago; that is to say, in the first decade of this century. The reason for the slide? Perhaps it was just the result of progressive weakening of the cliffs which had been oversteepened by glacial erosion during the time about 10,000 years ago, when ice flowed down Aspy Valley from a source on the Highlands plateau. Or, perhaps it was shaken loose by one of the two major earthquakes which rumbled through Cape Breton Island early this century. The one that occurred 21 Experience The Delta Difference Sydney's First Class Accommodation At Affordable Rates 'Waterfront location, in the heart of Downtown Sydney, adjacent to the City Hall, 3 blocks from Centre 200 Conference and Recreation Centre. ' 152 Harbourview Guest Rooms. A Indoor Pool & Fitness Centre. ?? A Exciting 55' Water Slide. A Continental & Maritime Cuisine. A Children's Menus & Prices, Kids 6 & under EAT FREE. DellaSydney Delta Hotels&Resorts 300 Esplanade, Sydney, N.S. BIP 1A7 (902) 562-7500 ToU Free Reservations Canada 1-800-268-1133 U.S.A. 1-800-877-1133 THE COOL WAY TOSENDFIOWERS. participating Dairy Queen? SYDNEY RIVER 539-7979 WE TREAT YOU MOHT' PORT HAWKESBURY 625-1700
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