Across
- 4. a solid copy of the shape of an organism
- 5. fossils in which minerals replace all of an organism, or a part, such as a dinosaur bone
- 8. the geologic principle that states that in horizontal layers of sedimentary rock, each layer is older than the layer above it and younger than the layer below it
- 10. a standard time scale of the geologic events and life forms in Earth’s history
- 11. a break in Earth’s crust long which rocks move
- 12. the process of measuring the absolute age of geologic material by measuring the concentrations of radioactive isotopes and their decay products
- 13. a hollow area in sediment in the shape of an organism or part of an organism
- 14. a drill core of ice that can help tell the climates of the past
- 15. fossils of widely distributed organisms that lived during a geologically short period
- 16. the time it takes for half of the atoms of a radioactive element to decay
- 19. these fossils provide evidence of the activities of ancient organisms
- 22. the age of rock compared to the ages of other rock
- 23. rock that forms when melted material hardens inside Earth or on the surface
- 24. type of fossil that is an extremely thin coating of carbon on rock
Down
- 1. when many types of living things become extinct at the same time
- 2. an igneous rock layer formed when lava flows onto Earth’s surface and hardens
- 3. a gap in the geologic record that shows where rock layers have been lost due to erosion
- 6. the age of a rock given as the number of years since the rock formed
- 7. scientists who study fossils
- 9. A description of surface features of land.
- 17. a bend in rock that forms where part of Earth's crust is compressed
- 18. an igneous rock layer formed when magma hardens beneath Earth’s surface
- 20. a term referring to all water that is temporarily frozen in polar ice caps, snow, permafrost, and glaciers
- 21. the process in which the nuclei of radioactive elements break down, releasing fast-moving particles and energy