Page 41 - A Geology Walk up the Clyburn Valley
ISSUE : Issue 67
Published by Ronald Caplan on 1994/8/1
old. That's when the granite was intruded into the crust. It's interesting, though, that it's intruded into a much older crust of the Bras d'Or terrane that we talked about before. (See "A Talk on Rocks: An Introduction to Cape Breton's Geology" in Issue 62 of Cape Breton's Magazine.) And it looks like what was happening is as the Bras d'Or terrane--one of the plates in the earth's crust--was pushing its way over the Aspy terrane to the west, the Aspy terrane was melting as it was buried deeper and deeper down into the crust into areas of higher and higher temperature. And as it melted, the magma was produced and gathered together, and then rose up and punched its way through the over? riding Bras d'Or terrane. And this Cameron Brook granodiorite is that magma--that hot granite that punched its way through the over-riding terrane that was bulldozing its way across the Aspy terrane, some 400- odd million years ago. So it's got an interesting significance as far as the origin of the different ter- ranes of Cape Breton Island is concerned. This is one of those granites that actual? ly stitches the two terranes together. It was generated in the Aspy terrane, but has intruded through into the Bras d'Or ter? rane. So we know the two of them were in place, or situated, stuck together, in more or less the present arrangement, by 403 million years ago. (We're passing through a forest here of more of these huge boulders--widely spaced.) We've gone past the main cliff on Beinn Franey now. And beyond Franey Brook, we won't see these boulders--we won't even see this rock again. Because the red gra? nite from which these boulders are derived ends at Franey Brook, and we move into a different bedrock type there. Most of these boulders probably fell down in the wintertime. They would be forced off by the action of ice going down the cracks and pushing the boulders off, spalling them off one by one. And I expect that most of these boulders fell in the wintertime, or in the spring when the ice Sydney Tar Ponds Clean-Up Inc. 500 George Place Box 12, Suite 250 Sydney, Nova Scotia BIP 1K6 SYDNEY TAR PONDS CANADA'S LARGEST HAZARDOUS WASTE CLEAN-UP A unique environmental project involving the removal of approximately 700,000 tons of waste sludge from a tidal estuary known as Muggah Creek. Sludge is dredged from the creek and transferred through a 1500-metre pipeline to two revolving fluidized bed incinerators for destruction. A COOPERATIVE INITIATIVE OF THE GOVERNMENTS OF CANADA & NOVA SCOTIA For further information: visit our public information centre, 500 George St., or phone 567-11331 Don't Just Do It • Do It Right! began to melt away from inside the cracks and re? leased the boulder to go cascading down the mountain face. There's every pos? sibility that the valley was plugged with snow as well. And the boulders would go bouncing off into the soft snow--particularly if it's beginning to melt--bouncing off into the soft snow and getting stuck at the bot? tom of the moun? tain slope. I'm sure some of them went much further out, across the alluvial fan, into the main river it? self, perhaps even to the other side of the valley. And no doubt some of them fell when there was still an ice sheet moving down this valley as well, landed on top of the ice, and then the ice gradually carted them out to sea. And you can see big boulders like this, actually, lying around the bays at Ingonish, made of the same material. (At this point, we've reached the area where the old maps indicate that gold mining took place. There is evidence of what might have been a concrete bunk- house, possibly a place where they refined the gold. We did discover what seems to be an entrance to the workings. See the photo, page 43.) Rob Raeside: I'm afraid there's very little to see Sun., Aug. 21* 1-6 P.M. FEATURING: Ashlcy Maclsaac Natalie MacMaster • Billy MacPhee Open Door Gang • Buddy MacMaster Mary Jane Lamond • Joel Chaisson Breaking Tradition • Tracey Dares Buddy MacDonald • Cornelia MacLeod Blanche Sophocleous Robt. Bouchard & Elizabeth | and MANY MORE FIDDLERS DANCERS and SINGERS!!! C Canteen Facilities • Refreshment Tent Crafts • Farmers Market 3 SKI Start Skiing! ...and Enjoy Your Winter Ski Ben Eoin's membership campaign is now underway! BY MAIL: P. O. Box 3 East Bay, N. S. BOA 1 HO PHONE: • 828-2222 • 828-2804 FAX: • 828-2550
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