SCIENCE

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Across
  1. 4. — Warm-blooded vertebrate animals characterized by hair/fur, nursing their young with milk, and giving birth to live young (with few exceptions).
  2. 5. — The amount of time required for half of the radioactive atoms in a sample of an element to decay.
  3. 7. — The thick, solid-to-semi-fluid layer of Earth's interior located between the outer crust and the dense core.
  4. 11. — The outermost, thinnest solid layer of Earth, divided into continental and oceanic crust.
  5. 12. — The preserved remains, impressions, or traces of ancient organisms found embedded in rock.
  6. 13. — The geologic era lasting from about 541 to 252 million years ago, marked by the rapid diversification of marine life, early plants, and land animals.
  7. 14. — A tectonic plate boundary where two plates pull apart from each other, creating new oceanic crust.
  8. 15. — A fundamental principle of geology stating that in undeformed layers of sedimentary rock, older layers lie at the bottom and younger layers lie near the top.
  9. 16. — The ancient supercontinent that included almost all of Earth's landmasses before it began breaking apart around 200 million years ago.
Down
  1. 1. — The soft, semi-fluid upper layer of the Earth's mantle directly below the lithosphere, over which tectonic plates float and move.
  2. 2. — The preserved remains of an organism that was widespread but existed for a relatively short geologic time frame, used to date and correlate rock layers.
  3. 3. — Secondary (or shear) seismic waves that move rock particles side-to-side and can only travel through solids.
  4. 4. — The liquid, fluid layer of Earth's interior composed mostly of iron and nickel, located between the inner core and the mantle.
  5. 5. — In geology (relative dating), the process of determining whether a rock or event is older or younger than another without specifying its exact age in years.
  6. 6. — The rigid, brittle outermost shell of Earth, comprising the entire crust and the uppermost solid portion of the mantle.
  7. 7. — The geologic era known as the "Age of Reptiles" (including dinosaurs), spanning from roughly 252 to 66 million years ago.
  8. 8. — Primary (or compressional) seismic waves that move rock particles back and forth in the same direction the wave travels; they are the fastest seismic waves and can move through solids, liquids, and gases.
  9. 9. — A tectonic plate boundary where two plates slide horizontally past one another, often generating frequent earthquakes.
  10. 10. — An active stratovolcano in the Philippines famous for its almost perfectly symmetrical conical shape.
  11. 11. — A tectonic plate boundary where two plates move toward each other, often causing subduction or mountain building.