Changing Earth

5. a crack in rock layers
7. an opening on Earth's surface that allows molten rock, called magma, to escape from inside the earth.
8. scientists who study past life on Earth.
9. form when organisms are preserved in sap, ice, or another material.
10. molten rock inside the earth.
13. imprints from when an organism leaves a mark on soft sediment and the sediment hardens.
16. natural events that can cause great damage.
18. scientists who study volcanoes.
20. brings older rock layers closer to the top.

1. the Earth's crust is made up of huge plates that move very slowly.
2. the remains of plants and animals that lived on land.
3. a law that states that the oldest rocks and fossils are in the bottom layer, while the newest are at the top.
4. a sudden, violent shaking of the ground caused by movement of giant plates in the Earth's crust.
6. are impressions of large organisms.
11. fossils of plants and animals that lived underwater.
12. Earth's development is divided into a series of distinct time periods.
14. an instrument used to record data about earthquakes.
15. a huge ocean wave caused by a disturbance in the ocean floor. Usually cause by an underwater earthquake.
17. scientists who study the structure of the Earth.
19. occurs when the movement of the Earth's plates causes rock layers to tilt.