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. This EarthCache takes you to the Swissair Flight 111 Memorial near Peggy's Cove, Nova Scotia. The granite rocks that make up this memorial are more than 450 millions years old - but do you notice anything odd about them? There are some inclusions - rock that differes from the surrounding granite - that help to tell the story of how these rocks were formed so many years ago. This earthcache studies these inclusions and helps to identify them.
EARTHCACHE REQUIREMENTS
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. There is no need to send individual answers.
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.
Observational Task
At GZ, you should be standing at the back side of the Swissair Flight 111 Memorial. You may find ruler or tape measure helpful to be able to answer the required questions.
1. Observation: Find at least one inclusion in the granite. Describe its shape, size, color, and texture. How does it differ from the surrounding granite?
2. Interpretation: Based on your observations and the descriptions above, which type of inclusion do you think you found (xenolith, mafic enclave, restite, or pegmatitic)? Why?
3. Timing: Do you think your inclusion formed before, at the same time, or after the granite? What clues led you to that conclusion?
4. Origin: What might this inclusion tell you about the geological history of the stone chosen for this monument? What does it suggest about the conditions when the granite was forming?
5. Photo: Include a photograph of yourself, your GPS, a signature item, thumbs up, etc with the Swissair Flight 111 Memorial in the background. You do not need to show your face in the photo, but your photo must be unique to you. In the event of group photos, please have each member of your group upload the photo (each log should have at least one photo uploaded).
Earth Science Lesson: What Are Inclusions in Granite and What Do They Tell Us?
Granite is the dominant rock type at Peggy’s Cove, however the rocks that make up this monument were NOT harvested locally. The Swissair Flight 111 memorial utilizes large granite boulders quarried from New Brunswick, fashioned to blend with the natural rocky landscape. This coarse-grained, intrusive igneous rock formed deep underground more than 400 million years ago, when molten magma slowly cooled and crystallized. But if you look closely at the monument here, you may notice that not all parts of the rock look the same—some areas contain inclusions: distinct chunks or patches of different material embedded within the granite.
What is an Inclusion?
In geology, an inclusion is a piece of rock or mineral that becomes trapped inside another rock during its formation. In granite, inclusions are common and can vary in size, shape, texture, and composition. They often appear as darker or differently textured patches within the lighter pink or grey granite.
Inclusions can come from a variety of sources and can form at different times. The presence and type of inclusion can tell geologists a lot about what was happening in Earth’s crust when the granite formed.
Types of Inclusions Found in Granite
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Xenoliths
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These are foreign rock fragments that were incorporated into the granite magma as it moved through the surrounding crust. Xenoliths may appear darker, finer-grained, or layered, and they often have sharp boundaries. They formed before the surrounding granite and were later engulfed by it.
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Restite Inclusions
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Mafic Inclusions (Also called mafic enclaves)
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These are blobs of darker, iron- and magnesium-rich magma that didn’t fully mix with the granite magma. They tend to be rounded or ovoid, and have a coarse or mottled texture. These inclusions formed during granite crystallization and represent magmatic mingling.
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Pegmatitic or Late-Stage Inclusions
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These may form when water-rich, mineral-laden fluids get trapped in pockets during the final stages of granite solidification. These inclusions might be lighter in color, contain large crystals, or appear vein-like. They formed after most of the granite had already solidified.
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How Can You Tell When an Inclusion Formed?
The relative age of an inclusion can often be determined by its relationship to the surrounding rock:
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If the inclusion is completely surrounded by granite and has sharp edges, it likely formed earlier (e.g., a xenolith).
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If the inclusion blends or transitions gradually into the surrounding rock, it may have formed at the same time.
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If the inclusion cuts across existing granite or fills a crack, it formed after the granite.
Why Are Inclusions Found in Granite?
Granite forms from molten magma that slowly cools underground. During its rise through the Earth’s crust, the magma may:
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Break off pieces of surrounding rock (xenoliths),
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Interact with other magma bodies (forming mingled mafic inclusions),
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Undergo chemical or mineralogical changes as it cools (producing pegmatites and restite),
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Experience late-stage crystallization processes that trap pockets of fluid or crystals.
These inclusions are important clues. They reveal the complex geological environment beneath Nova Scotia during the time of granite formation and help scientists reconstruct the tectonic history of the region—including collisions between ancient continents, mountain-building events, and the cooling of deep magma chambers.
Resources and Further Reading: