Page 47 - A Geology Walk up the Clyburn Valley

ISSUE : Issue 67

Published by Ronald Caplan on 1994/8/1

enough. So we seem to have this funny lit? tle triangle of slate caught up in the boundary between the two terranes, and we don't know where it belongs. We haven't yet figured that out. So it's one of the ques? tions that still has to be answered. We've given it the name, the Clyburn Brook formation, because it's best exposed up Clyburn Brook. Once you go beyond the end of the trail, there are some really spec? tacular volcanic rocks up there. There are volcanic ashes. And there are things that are called tuffs. These are rocks--when the volcano blew off, and blew all the ash and all the debris down the slopes of it, all these great volcanic coarse debris boulders and so on--chunks of the sides of the volcano--all got caught up together. And were laid down as an ash. And then all welded together because they were still very, very hot. And we find some of these tuffs up there as well. They've all undergone a light touch of metamorphism. They're all greenish- coloured rocks; they've got the same chlorite mineral in them. But what their source and what their actual age is, we're still a little bit uncertain. But it seems that they're not Precambrian any longer. We've at least got them up 150 million years in age. (Do you have a lot of questions like that, unsolved?) Probably have 40 years worth of them, yes, to work on. There are a lot of questions. So far all that we've really done is map the occurrence of the different rock types in the Highlands. We really don't know how they all fit in in detail, each one with each other yet. There's quite a lot still to do with that.... (We are approaching the end of our walk, deep into the Clyburn Valley.) As you go down past the cabin at the end of the trail, there's a bit of a path down through the woods down to the river. And the first rocks--bedrock--that you'll en? counter are the black slate of the Clyburn Brook formation. This is a black slate which we now understand is Silurian in age--it's about 430 million years old. .the Gem of Victoria County ''? Our thanks once more to our guide, geologist Rob Raeside. Most of the rocks that you see, though, are just regular black slate. They've got a very strong cleavage, which runs out in? to the river. But you'll see a couple of white stripes, or very pale green stripes, in some of the rock. And those are layers of straight volcanic ash. Somewhere around here, 430 million years ago, there was a volcano on the scale of Mount St. Helens or Mount Pinatubo, that was blowing its top periodi? cally. And the ash which was erupted from that volcano drifted out and was de? posited as a layer in the mud- banks of the shallow seas in the area. And these layers are preserved today-- The Goose Cove Pottery & Gift Shop is located on the Cabot Trail off Highway #105 on Exit 11 Open 7 days a week • 9 a.m. to 5p.m. SHOP: open till Labour Day STUDIO: open by chance or appointment Visitors are welcome to browse at the pottery studio located on site The Goose Cove '>*??*l POTTERY '' & GIFT SHOP Carole Ann MacDonald Potter //r.r. / Badd K-' .#4 (St. Ann's) Baddeck, Nova Scotia BOE IBO (902) 929-2293 Sew Inclined A Workshop 1 IN THE Glen • Custom Orders • Sewing Services • Designer Clothing & Accessories Tarbot, Cape Breton open 7 days a week, 9 - 5 Wanda MacDonald AND Barbara Longva Showcase of Work on Display (902) 929-2050 PIPER'S TRAILER COURT Featuring: Fully Licensed Dining Room Laundromat Mini-Mart Ocean-Side Campsites Swimming Pool 929-2233 929-2067 Indian Brook on the Cabot Trail (Halfway between Baddecl(and Ingonish) From either direction on the Cabot Trail, plan for comfort and welcome Piper's Old Manse GUEST HOUSE with Bed and Breakfast . OPEN YEAR ROUND ' In either direction, it's a beautiful way to go!

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