1. Vocab

2. Fossil Remains, imprints, or traces of prehistoric organisms

3. Permineralized Remains Fossils in which the spaces inside are filled with minerals from groundwater

4. Carbon film A thin film of carbon residue that forms a silhouette of the original organism

5. Mold A cavity in a rock left behind from a decaying organism

6. Cast A copy of the original object formed by mineral-rich water or other sediment

7. Index fossil Remains of species that existed on Earth for relatively short periods of time, were abundant, and were widespread geographically.

8. Principle of Superposition The oldest rocks are on the bottom and the rocks become progressively younger toward the top

9. Relative age An objects age in comparison to the ages of other things

10. Unconformities A gap in a rock sequence

11. Absolute age The age, in years, of a rock or other object

12. Radioactive decay The process of breaking down

13. Half-life The time it takes for half of the atoms in the isotope to decay

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

15. Uniformitarianism Principle that states that Earth’s processes occurring today are similar to those that occurred in the past

16. Weathering The breaking down or disintegration of substances such as rocks and minerals by physical, chemical, or biological changes

17. Erosion The movement of sediment or soil from one location to another by means of water, wind, or ice

18. Deposition When particles carried by water, ice, or wind are deposited in another location

19. Metamorphic rock Rocky material experiences intense heat and pressure in the crust of the earth.

20. Igneous rock Formed when magma cools and makes crystals.

21. Sedimentary rock Form at or near the earth's surface at relatively low temperatures and pressures primarily by: deposition by water, wind or ice