Wild Northerner Magazine Fall 2017 - Page 53

“The main action of the most recent glaciers was that it scoured the rock clean off any superficial cover that formerly may have lain on the surface, thus exposing and smoothly polishing the underlying bedrock which we know today as the largest classic karst limestone pavements on the island. The grikes average about 13 cm or so across. As the fractures widen through dissolution, the ground water flows to the water table. The importance of recognizing such passageways in bedrock cannot be overstated, because they bear on locating landfills, sewage treatment and management of livestock manure,” Russell said.

Russell explained the tragic events at Walkerton, situated on the limestone laden Bruce Peninsula.

“In May, 2000 water movied quickly through the fractured bedrock of clints and grikes, and, combined with subsequent lack of chlorination caused an outbreak of E.coli (Escherichia coli) bacteria in the town’s water supply,” he said.

The result was more than 2300 cases of gastrointestinal disease and eventually seven deaths. It was attributed to farm runoff into an adjacent well that had been known for years to be vulnerable to contamination and to two employees of the Walkerton Public Utilities Commission who could have admitted (falsifying reports) to the contaminated water sooner.

Walkerton Tragedy

The question to Russell was, is there a location that represents both the alvar community and the karst process?

“There is some beautifully exposed pavement on both sides of the road with excellent development of clint and grike karst,” said Russell. “It is one of my favorite places to visit, especially in October when the maple trees turn red and yellow. The trees are short bonsai-like due to the lack of soil.”

This location is found at N45° 43’ 38.8” W82° 14’ 43.4” or WGS 84 17 T E403094 N5064519.

It is found north of Providence Bay, off Highway 551 (SW corner of Mindemoya Lake). Highways 551 and 542 merge in Mindemoya, the village. Turn north on to Monument Rd. (west of Mindemoya) and drive north, 1.5 km; this is quiet country back road, good for parking. It is a wonderful site to see the fractures and a multitude of sensitive ferns, stunted Junipers and exposed dolostone pavement with no topsoil.

And watch out for the erratic rocks, ranging in size from pebbles to huge boulders. These erratics, often rocks of a different type to the limestone, are one of the most visible indicators of glaciation, contrasting the limestone pavement.

There is so much to see on Manitoulin Island including finding trace fossils at Gore Bay and the Cup and Saucer Trail, close to Little Current. And don’t miss Bridal Veil Falls at Kagawong. ‘Manitoulin Rocks!’ is an ideal reference guide for tourists, teachers, students, nature lovers, or anyone else who wants to understand the natural history of this beautiful Island. It contains 131 pages, full colour production including more than 150 original line drawings and photographs. The first half of the book treats a broad range of topics and concepts required to appreciate the geology of Manitoulin Island, using local examples wherever possible. The second half of the book is a detailed field guide to 50 field stops on and north of Manitoulin Island to examine rocks and landforms. Location maps and clear driving directions are provided for each stop. (Pers. Comm. a tip of the hat to the authors, I would give it a “camp badge,” this is how information for visitors should be presented, with GPS coordinates.) You can order it through the Earth Sciences Museum, University of Waterloo (earthmuseum@uwaterloo.ca) or 519-888-4567 ext.32469 on online.

Most people know a crack when they see one, but that doesn't mean they understand or have thought much about cracks like the clints and grikes of Manitoulin Island. Understanding the Walkerton tragedy through visiting the Manitoulin alvars may prove to be more than just interesting.

Backroads Bill is the founder of the Canadian Ecology Centre and teaches part time at Nipissing University and Canadore College. Contact the author at wilstonsteer@gmail.com or www.steerto.com ; LIKE on Fbook, Back Roads Bill Steer.

Go for a Visit

Manitoulin has unique sedimentary rocks; stop at the rock cuts ans look for fossils.