Connecting people with nature in Ontario's Mississippi Valley

The following account of the Wednesday October 25, 2017 ‘geology’ event Reading the Rocks.

Wednesday was a beautiful cool, crisp October morning as the Mississippi Valley Field Naturalists and friends gathered in  Metcalfe Geoheritage Park for “Reading the Rocks,” led by Neil Carleton, a founding MVFN member. It was the perfect backdrop for the drama that was about to unfold. Four dozen heads tilted backward as Neil began our breakneck journey through geological time, by sweeping his arms skyward, pulling the Grenville Mountains from their ancient roots, to dizzying heights. Beneath these towering behemoths, we imagined the tremendous heat and pressure that would transform the rock, limestone to marble and shale to schist, 20 km beneath our feet.

 

Meanwhile, as the continents restlessly wandered the globe, Neil’s arms fell as the equatorial landmass that would become North America was covered in a succession of tropical oceans. His voice filled with awe as he described the diversity of marine life in the warm, shallow seas. Pointing downriver to a distant landmark, he was ready to take us further on our exploration in time, but closer to the present when a cooling climate triggered a global ice age.  Tipping the landscape on its head, the outcrop now stood 2 km atop a glacier. We could almost hear the grinding of the massive continental ice sheet in its relentless advance, scouring the landscape and smoothing the bedrock to a polished finish.  Neil’s hands and arms floated away from his body as the ice melted leaving behind the rock debris known as glacial till.

Neil then turned to the scientific record of the events he had described so eloquently. It is all there in the folded layers, bedrock striations, and colourful minerals if you take the time to read the rocks. He pointed to a large slab of micaceous schist that formed deep in the roots of the Grenville Mountains. He traced the fossils of predatory cephalopods, the uniquely preserved burrows of soft-bodied organisms, and the rippled sediments frozen in the rock of what was once the near shore bottom of an Ordovician Sea. Ruler straight lines on the face of one boulder and a conglomerate rock formed by the cementation of igneous, sedimentary and metamorphic rocks formed in very different ways, in very different places, that had been carried in and under the ice sheet, and left behind were evidence of the melting ice as it receded from the area only some 11,500 years ago.

The group then moved to tables of fossil specimens that Neil had set up for closer examination. A microscope allowed a look at the fine details of the corals, brachiopods, and trilobites that inhabited the prehistoric seas of our area.  A scavenger hunt of geological words further engaged us in our exploration of rock and fossils. Neil wrapped up the morning by answering questions and distributing “loot bags” containing local rock samples with labels, along with shells from the Champlain Sea.

Metcalfe Geoheritage Park is located  at the base of  Bay Hill (i.e. at the rivers edge at 250 Almonte Street in Almonte. For directions see http://mvfn.ca/events/reading-the-rocks/).  Try your hand at reading the rocks. There are pamphlets at the park to help you, or bring along your smartphone and access in-depth information, through the QR codes located at the base of each sample. Learn what the rocks have to tell us about the fascinating geological history of Almonte and the surrounding area.

By Gretta Bradley

Almonte's Metcalfe Geoheritage Park photo P. Donaldson (1280x591)

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Wednesday October 25, 2017

250 Almonte St., Almonte, Ontario

The display specimens at Canada’s first municipal geoheritage park, in Almonte, Ontario, collectively illustrate many of the features that allow geologists to unravel Earth’s remarkable geological history.  “Reading the rocks” with Neil Carleton, on our visit to Almonte’s Metcalfe Geoheritage Park, will take us on a journey far back in time to colliding continents, towering mountains, tropical ocean depths, and a landscape locked in ice.

Reading the rocks

Neil, a geologist, naturalist and well-known retired educator, is one of the founding members of MVFN.

Take home a sample of genuine Canadian Shield schist.  If your camera phone has an app for scanning QR codes, be sure to bring it along.

Time: 10 AM to noon

Location and directions: the entrance to Metcalfe Geoheritage Park, at 250 Almonte Street, is at the bottom of “Bay Hill” below the lower falls in Almonte. From Hwy 29: turn left onto Almonte St. at the lights (if approaching from Pakenham) or right (if approaching from Carleton Place direction) and proceed down the hill (the geoheritage park is on the left on the river side); if coming from downtown Almonte via Mill Street, turn left from Mill Street onto Almonte Street and follow along a short distance downhill to the Almonte Geoheritage Park on the right.

Difficulty: Easy, even ground, cement walkway; less than 0.5 km of walking; bench available on site and picnic tables nearby, but there will be significant standing; wheel chair accessible.

Cost: no cost

Parking: there is free parking on-site and across the road.

Facilities: there is a washroom on-site at the opposite end of the park closer to the hydro station and another reached via a short walk downtown to the Heritage Mall. There are also picnic tables.

Bring: protection from the sun and inclement weather, drinking water, and a camera.

Pre-Registration: pre-registration is required. To pre-register, or for more information, please contact Gretta Bradley at

 

 

Almonte's Metcalfe Geoheritage Park photo P. Donaldson (1280x591)

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