Welcome to my Earthcache! An Earthcache is a special type of geocache where there is no container to find - instead you are looking for a unique geological feature of the area and need to answer questions, as well as posting a picture, in order to claim the find. At this location, you will be observing the cracks within the granite at Peggy's Cove, one of the most photographed places in Canada. This earthcache will review the three main processes that caused the cracks to form in the granite in this area.
As with all of my ECs, I am not looking for PhD thesis level responses, but I am hoping that you take some time to enjoy the area and learn something new. Please include a list of all cachers with your answer, if answering for more than one caching name.
To claim a 'find' for this Earthcache you must answer the following questions and send your answers in a message or email to the owner using the link at the top of the page. You can log your find with a photo at GZ. Send your answers to the tasks. I will be in contact if there is a problem, no need to wait for a response as long as the required photo is included in your log.
Questions to Answer:
1. Observe the cracks in the granite. Are they mostly straight, angular, or curved? Do they follow straight lines, or are they broken or wavy? Are they mostly horizontal, vertical, or a combination of both?
2. What does this shape tell you about how they might have formed? Hypothesize which of the three methods you feel was responsible for most of the cracks here, and why.
3. Can you find any evidence of glacial activity (e.g. striations, polished surfaces, erratic boulders)? If yes, describe what you see.
4. Photo Requirement: Take a photo of yourself (or just your GPS device, or your geocaching name on a piece of paper, or your signature item, a thumbs up) with the granite boulders of Peggy's Cove in the background. You are not required to show your face in the photo, but each geocacher should upload an image with their log indicating that they were there. You are also welcome to share other photos of your visit to this beautiful area, but at least once image should show you at or near a visible crack.
Earthcache lesson:
The dramatic landscape at Peggy’s Cove is made of granite bedrock — a very hard, crystalline igneous rock that formed deep underground around 470 million years ago as molten magma slowly cooled beneath the Earth’s surface. They began as mud and sand in a deep ocean basin near ancient Africa. They built up and were eventually compacted into shale and sandstone. As tectonic plate movement caused North Africa and North America to collide 400 million years ago, the shale and sandstone were squeezed between the two continents and heat and pressure transformed them into slate and quartzite.
Heat from the continental collision also melted rock at the base of earth’s crust 375 million years ago. The molten granite was less dense than the solid rocks around it so it rose through the earth’s crust. As it rose and got further from the heat deep inside the earth, it cooled and solidified several kilometres below earth’s surface.As this magma cooled and hardened into granite, it contracted, forming a network of shrinkage cracks known as cooling joints. These original cracks are the first chapter in the story of Peggy’s Cove's fractured rockscape.
Uplift (upward pressure) from the collision continued to push the granite toward surface, while weathering and erosion removed the slate and quartzite above. Eventually erosion exposed the granite at surface, where it is now.
Three Major Forces Shaped the Cracks You See Today
1. Cooling and Solidification of Magma
When the South Mountain Batholith formed (the massive granite body that includes Peggy’s Cove), the magma cooled slowly. As it cooled, the rock contracted and cracked internally. These cooling joints are the earliest fractures in the granite — and many are still visible today as straight or blocky separations in the rock.
2. Uplift and Release of Pressure
Over millions of years, the overlying rock layers eroded away, exposing the granite at the surface. As the overburden was removed, the pressure holding the rock together decreased, allowing existing cracks to expand and new ones to form. This unloading process allowed the granite to fracture further.
3. Glacial Activity
During the last Ice Age, glaciers covered this region, grinding and scouring the exposed granite. These massive ice sheets moved across the rock, plucking and widening the existing fractures. Glacial movement helped shape the smoothed surfaces and angular boulders seen today — some of which were carried and deposited as glacial erratics.
A Landscape Still Changing
Although the major cracking processes happened deep in the past, modern weathering — from freezing and thawing, salt spray, and plant growth — continues to slowly widen some of these fractures. This weathering will continue to expand the cracks, eventually leading to large pieces of the granite breaking off and tumbling into the water below.
Visitor Guidelines
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Use caution — granite surfaces can be slippery and uneven.
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Stay off wet or blackened rocks near the ocean, which are dangerous due to unpredictable waves.
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Please respect the natural environment: take only photos, leave only footprints.
Credits & References