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Across 4. one of the three main rock types and formed through the cooling and solidification of magma or lava 5. two pieces of land change their vertical position compared to one another 6. the era, which ran from about 542 million years to 251 million years ago, known for great change on Earth with plants becoming widespread and the first vertebrate animals colonizing land. Also known for the breaking up of a supercontinent and the formation of another 9. two pieces of land move horizontally 10. the theoretical classification system for the layers of rocks and fossils that make up the Earth’s crust 17. an interval of time known as the age of the reptiles from about 252 to 66 million years ago 18. rock formations from magma that cools and solidifies above the surface of the crust 19. rocks that are subjected to high heat and pressure which causes a profound change in form

Down 1. a break or fracture in the ground that occurs when the Earth’s tectonic plates move or shift and are areas where earthquakes are likely to occur 2. a system that divides Earth’s history into intervals of time defined by major events or changes on Earth 3. rock that has formed through the deposition and solidification of material, especially transported by water 7. an era that spans about 65 million years ago also known as the age of the mammals 8. the era of time prior to 600 million years ago, covering 90% of Earth’s history divided into three eras: Hadean, Archean, and Proterozoic 11. rock formations from magma that cools and solidifies within the crust of the planet 12. atoms of the same element that have the same number of protons but different numbers of neutrons 13. the process of becoming extinct where a species comes to an end or dies out 14. a radioactive isotope which is present in organic materials and is the basis for radiocarbon dating 15. a continuous process by which rocks are created, changed from one form to another. Destroyed, and then formed again 16. a core sample of ice removed from an ice sheet most commonly in the polar ice caps of Antarctica; provides information on climate from different periods (up to almost one million years) that can be used for research