Across
- 4. The numeric age of a layer of rocks or fossils that can be found by using this method.
- 6. In a sequence of sedimentary rock layers, the newer rock layers will be on top of the older ones.
- 7. A major division of geological time, subdivided into eras.
- 8. Any feature that cuts across a sequence of rocks, is younger than everything it cuts.
- 9. The amount of time it takes for half of a remaining isotope to decay to a daughter product.
Down
- 1. Recognized to represent a period of time, or on radioactive decay of specific isotopes.
- 2. A fossil that is useful for dating and correlating the strata in which it is found.
- 3. Any rock or fragment that’s included inside of another rock is older than the rock in which it is included.
- 5. An expert in or student of geology.
- 6. You may not know the exact age, but you can tell if one rock layer is older relative to another layer.