Page 35 - A Geology Walk up the Clyburn Valley
ISSUE : Issue 67
Published by Ronald Caplan on 1994/8/1
Examining Layers Exposed by a Recent Small Landslide Rob climbs up a landslide alongside the trail. The trail it? self was probably underwater in the spring, encourag? ing the instability. The landslide has exposed "the till • the glacial boulder- clay material that was deposited dur? ing the late Ice Age as the ice was melting." Right: Rob points out the layered sand and gravel beds. "Each gravel bed would be one winter's accumula? tion. And the next sand layer would be the summer's accumulation. The next gravel would be the winter accumulation, and so on." I would estimate that today, perhaps at least as much again as we see flowing on the surface is flowing underneath. And maybe twice as much is flowing underneath, through the boulders. I think Clyburn Brook probably flows on surface pretty well all the summer long. Otherwise you wouldn't find fish in the river in any substantial quantity. And it appears to be a fishing river. (We stop and look at the fallen bank alongside the trail. See photos above.) It's a good landslide, this one. This just happened last fall, or last winter. This is a brand-new landslide. There's no vege? tation growing on it yet. It may be as re? cent as maybe just 6 weeks old or so-- probably in the spring floods. When the river backs up in the springtime, and the water's going downstream at the great rates that it goes at, the toe--the bottom of the landslide--we call it the toe of the landslide or the toe of the bluff--gets underwater, lies underwater. And therefore the weight of the overbur? den, the rocks and sand and clay on top, is lifted a little bit. And the whole thing is no longer as stable. And with the MacDonald and Robertson Ltd. 448 Charlotte St., Sydney Electrical Contractors with 60 Years of Experience to Sen/e You Specializing In Electrical Upgrades and Rewiring. (Crack filling & clean-up after the job.) All electrical jobs, large or small. Free estimates. Commercial & Industrial jobs, r-'m oocc Seniors discounts. O04-o250 AtaKfloweri Atal Over 75 Stores & Services Gf?E4r.., SERVICE • GREAT... SELECTION • Gf?E4r.,. PRICE "All Under One Roof!" SENIORS' WALKING CLUB: 539-0862 800 Grand l-ake Road, Sydney, N.S. B1P 6S9
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