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Page 44 - A Geology Walk up the Clyburn Valley

Published by Ronald Caplan on 1994/8/1 (264 reads)

of rock found at this part of the trail.) This boulder is the Cameron Brook granod? iorite. That's the red granite that we saw to begin with. And this is a boulder of Ingonish River tonalite, the black-and- white speckled rocks that we looked at in the riverbed. Actually, this is not a common rock all over the world. But it is a common rock here in the eastern Highlands. This rock, this rather layered and striped one, however, was derived from the black- and-white speckled one. This rock comes from a fault zone, or a shear zone, in the earth's crust, where the two plates were moving past each other. And if you start off with a black-and-white speckled dio? rite, and you take it down to great depths in the crust and stretch it, like you were stretching an elastic band or a piece of plastic that gives a little bit--it doesn't break, but it pulls out, producing a texture or a rock which we refer to this as a sheared diorite. Everything's all flattened out by the forces of the plates moving past each other. When we think of a fault zone, we often think of something happening high up near the surface of the crust. At the surface, when the fault gives, it breaks--it's fairly brittle. But if you go down deep in the crust of the earth--if you go down some 10, 15, 20 kilometres--then instead of getting a fracture, the rocks get sort of drawn out.... It gives a layered look to it. It's a metamorphosed igneous rock. The metamorphism was the process of shear? ing it and stretching it. And the igneous was what it was before it was stretched.... This sheared tonalite that is derived from it, you'll find everything in between the real black-and-white speckled rock and the very stretched rock. Those are the domi? nant rock types around here. At least for the next little ways, until we get to the next brook.... (We've come to the alluvial fan, Franey Brook.) And there was probably at one time a lakebed, a shallow lake here, which would drain through the boulders, and drain away. But everywhere you can get a shallow lake, still water, then there's an opportunity for finer sediment to gather, and it would make it a more fertile spot. So this would be probably the best place in the upper reaches of the Clyburn Brook here, or upper reaches along the trail, as far as agriculture is concerned. But the position of the river today is very dif? ferent from what it was 80 years ago, in this area. GLORIA'S ONE HOUR PHOTO (902) 224-3733 0' IConica CHETICAMP ONE HOUR PHOTO • PHOTO UNE HEURE KONICA FILMS • KODAK FILMS • CAMERA BAHERIES OPEN MONDAY to FRIDAY 10 a.m. to 6 p.m. YEAR ROUND and SATURDAY 10 a.m. to 5 p.m. (July & August only) "We are located 1/4 mile south from the HARBOUR RESTAURANT' DONT MAKE A MOVE WITHOUT US! • LOCAL • LONG DISTANCE • OVERSEAS LARGE OR SMALL - WE MOVE IT ALL MOFFATT Moving & Storage SAFELY, EFFICIENTLY & INSURED CALL THE PROFESSIONALS • OVER 40 YEARS EXPERIENCE Financing Available O. A. C. 30- to 90-Day Interest Free VISA I Mastercard on Long Distance FREE ESTIMATES 562-0222 80 MARINE DR., SYDPORT '' AtlaS Weekends & Atter Hours VAN LINES / AGENT 564-0963/562.1978 It's total? ly changed. I can't see any obvious river chan? nel right through here. Sometimes you can see the old (man-made stone) walls that go back perpendicu? lar to the valley slope, to "CONTINUING TO SERVE THE HEALTH CONSCIOUS" st'' & He'L Cholutr] BRUCE & UNDA MACRA' ' invite you to drop in & have a cup of freshly brewed coffee & a delicious homebaked goodie • or indulge yourself with a tasty selection from our Deli. NOW FEATURING! I Mouthwatering LOBSTER SANDWICH on our famous, freshly baked bread! NYANZA (Trans-Canada Hwy. 105) 295-2275 NEW SUMMER HOURS: MONDAY-SATURDAY 8 AM - 8 PM SUNDAY 10 AM - 8 PM SALES ?? SERVICE ?? INSTAIIATION J?T WELLS & PUMPS i'T" Wll/i/ate' - it's/l(itaMll'Better " • Water Wells: DrUled & Dug > • Pumps • Test Holes • Water Conditioners Serving Cape Breton E S T M O U {Ucence No. 264)
Cape Breton's Magazine
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