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EarthCache: Xenoliths at Prince Diponegoro National Statue
Tasks to Complete:
To log this EarthCache as found, answer the following questions (answers can be found in the listing and on-site through observation):
You are standing next to the Prince Diponegoro National Statue. On the left side of the Statue (left side of the horse and the Prince), find the granite panel in the third column from the left and the second row in the bottom. See the photo for a reference.
You will find two eye-catching places in this panel, marked as A and B. See the photo.
- Describe what you see in A and B places. Are there xenoliths? What size and color? If A or B is not a xenoliths, what it might be?
- Based on your observations, guess the origin of the xenoliths there based on the information from the listing.
- Why do you think xenoliths in question did not melt in magma?
- Take a photo of you or your personal geocaching item at the posted coordinates with the National Statue in the background and post this photo with your log.
📩 Send your answers to me via a message on Geocaching.com. You may log your find immediately after sending your answers, without waiting for confirmation. If there is an issue, I will contact you.
🪨 What are Xenoliths?
A xenolith (from Greek xenos = foreign, lithos = rock) is a fragment of a different type of rock that becomes enveloped by magma before it solidifies. As the granite (or other igneous rock) cools and crystallizes, the xenolith remains trapped inside, often as a visually distinct patch due to its different color, grain, or mineral composition.
🧬 How do Xenoliths Form?
- Magma rises from the Earth's mantle or lower crust.
- It assimilates pieces of older rocks it comes in contact with.
- These pieces survive the journey without fully melting.
- When the magma cools and hardens into granite, the foreign rocks are preserved inside as xenoliths.
🎨 Types of Xenoliths by Color
Xenoliths can vary in color depending on the type of rock they originated from:
- Dark (black/grey) – often basaltic or gabbroic fragments.
- Greenish – may come from ultramafic rocks (e.g. peridotite).
- Reddish – could contain iron-rich minerals or be sedimentary in origin.
- Light (white/beige) – may be older granitic or metamorphic rocks.
📚 Additional Notes
- This slab is a great example of how even common building materials can tell us complex geological stories.
- Please be respectful—this is a public structure, so do not damage or deface the surface.
