Across
- 2. a method used to determine the specific age of an object in actual years
- 4. any material (like a fragment of another rock, a mineral crystal, a or a trapped gas bubble) that is found inside a larger rock or mineral
- 5. by observing current events like erosion and sedimentation, we can understand how past geological formations like mountains and valleys were created over long periods of time.
- 7. a gap in the sequence of rock layers, representing a period of time where no new rocks were deposited, or where existing rocks were eroded away
- 8. the time it takes for half of a group of unstable atoms to decay into a different element
- 11. the process where molten rock (magma) forces its way into or between existing rock layers beneath the Earth's surface and then cools and solidifies
- 13. a system for organizing Earth's 4.6-billion-year history into a "calendar" of divisions like eons, eras, periods, and epochs
Down
- 1. a geology principle that states that in an undisturbed sequence of rock layers, the oldest layers are at the bottom and the youngest are at the top
- 3. a preserved remnant or trace of ancient plant or animal life, like a bone, tooth, footprint, or impression
- 6. a fossil of an organism that lived for a short, specific period of time and was widespread geographically
- 9. a scientific method that determines the age of rocks and other materials by measuring the decay of radioactive isotopes inside them
- 10. a principle that states any geologic feature that cuts across existing rocks is younger than the rock it cuts
- 12. a science method that determines the chronological order of events without assigning a specific numerical age