1. Chapter 13 Earth Science Clues to Earth’s Past

2. Words to Know – Section 1 Fossils fossil Permineralized remains Carbon film Mold Cast Index fossil

3. remains, imprints, or traces of prehistoric organisms that can tell when and where organisms once lived and how they lived. fossil

4. Fossils in which that spaces inside are filled with minerals from groundwater. Permineralized remains

5. Thin film of carbon residue preserved as a fossil. Carbon film

6. A type of body fossil that forms in rock when as organism with hard parts is buried, decays or dissolves, and leaves a cavity in the rock. mold

7. A type of body fossil that forms when crystals fill a mold or sediments wash into a mold and harden into rock. cast

8. Remains of species that existed on Earth for relatively short periods of time, were abundant and widespread geographically, and can be used by geologists to assign the ages of rock layers. Index fossil

9. Words to Know – Section 2 Relative Ages of Rocks Principle of superposistion Relative age unconformity

10. States that in undisturbed rock layers, the oldest rocks are on the bottom and the rocks become progressively younger toward the top. Principle of superposition

11. The age of something compared with other things. Relative age

12. Gap in the rock layer that is due to erosion or periods without any deposition. unconformity

13. Words to Know – Section 3 Absolute Age of Rocks Absolute age Radioactive decay Half-life Radiometric dating uniformitarianism

14. Age, in years, of a rock or other object; can be determined by using properties of the atoms that make up materials. Absolute age

15. Process in which some isotopes break down into other isotopes and particles. Radioactive decay

16. Time it takes for half the atoms of an isotope to decay. Half-life

17. Process used to calculate the absolute age of rock by measuring the ratio of parent isotope to daughter product in a mineral and knowing the half-life of the parent. Radiometric dating

18. Principle stating that Earth processes occurring today are similar to those that occurred in the past. uniformitarianism