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Backyard Geology

Devils Tower against a blue sky background with the boulder field and pine trees in the foreground.
Studying rocks can tell us a lot about how the Earth formed and how it changes.  What does your rock tell you about your backyard?

NPS photo

It’s time to channel your inner rock star! Devils Tower is made up of a very unique type of rock called phonolite porphyry (PHONE-o-lite por-FY-ree). This type of igneous rock formed when magma (molten rock) cooled very slowly underground. Explore the rocks around your home as a junior geologist, or scientist who studies the earth!

Find a rock and observe it (study it carefully). Use the Field Notes below to guide your observations and record your notes in a journal or sheet of paper. You can print the Field Notes sheet to use.

Put your rock on display for a day and share what you’ve learned with your family! When you’re done, remember to put the rock back where you found it. Junior Rangers practice Leave No Trace ethics by not taking anything from its home in nature.

Field Notes

Find a rock in your backyard, and examine it closely using your five (5) senses.

Sight

What color is your rock?

Do you see any of the following? If so, describe them!

  • Crystals:
  • Fossils:
  • Dark or light bands:
  • Pieces of other rocks:

Touch

What does your rock feel like?

  • Does it feel smooth or jagged?
  • Does it feel chunky?
  • Does it feel like sandpaper?
  • Does it feel porous (holey)?

Sound

Tap your rock with your fingernail. What does it sound like?

Tap your rock with another rock. What does it sound like?

Smell

What does your rock smell like?

Taste

Ask an adult for permission before licking your rock!

Sometimes geologists lick rocks to learn more about the texture or composition of the rocks they study.

Lick your rock. What does it taste like?

  • Is it salty?
  • Do flakes come off on your tongue?

Bonus – Rock Type

Learn about the three types of rock with examples of each type.
Rock Type How It Forms Examples

Sedimentary

Sediments get packed together (sand, other bits of rock, organic matter, etc.)

Sandstone
Limestone
Coal

Igneous

Cooling of molten rock: magma (underground) or lava (above ground)

Granite
Obsidian
Pumice

Metamorphic

Other rocks experience extreme temperature and/or pressure conditions

Marble
Gneiss
Quartzite

How do you think your rock formed?
What kind of rock do you think it is?

Great job! You’re a rock star!

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    Last updated: May 8, 2020