Wondering why there are so many large boulders scattered around Peggy's Cove, and why some of them are precariously balanced on smaller boulders or steep slopes? What you see is the work of glaciers.
Twenty thousand years ago, continental glaciers one kilometre (0.62 miles) thick inched their way across this area. As these glaciers moved, the base of each ice mass would continuously thaw and freeze.
During the thaw, water filled existing fractures in the granite bedrock. When the water froze, the glacier plucked up and carried away chunks of rock. The more the glacier moved, the more rock it gathered. When the glaciers melted, they left behind the boulders you see today. Geologists call them perched boulders or erratics.[1]
Speaking of rock, do those smooth-shaped rocks in the region look like whales' backs to you? These formations are called roches moutonnées.[2] The smooth, sloping side shows the direction from which the glaciers came; the opposite side is generally steep and jagged. If you look closely, you'll see grooves and deep scratches on the surface of the granite called striations.[3] These scratches were created by rocks lodged in the base of the ice - enduring evidence of how the glaciers made their mark on Peggy's Cove.
Gate Rock
You may have noticed a very large boulder
alongside the road as you entered the village. It's known as Gate Rock, because there was once a set of gates here to keep grazing cattle out of the village. Children from the village would open the gates for visitors, and receive a coin for their kindness. The gates were later removed as roads improved and the number of cars visiting the community began to increase.
[1] Perched Boulder
This large, rounded boulder of granite was dropped, somewhat precariously, from within a melting glacier as it retreated. You'll notice that some boulders are stacked on each other in a chaotic manner, and all are irregularly scattered about the landscape.
The person you see atop this perched boulder is a professional. These rocks are dangerous and unstable. For your safety, we ask that you not attempt to climb any of the many perched boulders you'll see around Peggy's Cove.
[2a] [2b] Sculpting Of Roche Moutonnées
See the sloping landform? This is a roche moutonnée that was created by the sculpturing action of a glacier. The shape, shallow slope and steep side show the direction the glacier travelled, in this case towards the left, or west. The picture below illustrates the movement of the glacier (yellow arrows), which occurred over thousands of years.
[3] Glacial Striations
Wondering how those deep gouges or scars were made in the granite? They
are striations (top to bottom), which are made by rock fragments being pushed over the granite by an advancing glacier.
Glacial Scale
It took millions of years of erosion to reveal the granite you see here today, along with glacial activity to sculpt and polish it. These glaciers, approximately 1-3 kilometres (0.62-1.86 miles) thick, covered much of North America tens of thousands of years ago, before receding 15-20,000 years ago. Locally, the ice eroded the underlying rock by plucking out blocks outlined by fractures and then polishing the surfaces.
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