1. Geologic History

2. Relative Time Places events in sequence.
Does not give the exact date of an event.
Uses the Law of Superposition

3. Absolute Time
Gives a date or time of an event.
Radioactive dating

4. Law of superposition: in an undisturbed set of rock layers, the oldest rocks are on the bottom

5. Intrusion: occurs when molten rock moves through an existing rock layer
Younger than the rock layers it goes through

6. Extrusion: occurs when molten rock reaches Earth’s surface.
Older than the rock layers above it
If the extrusion is buried under another rock layer, it has NO contact metamorphism on top

7. Sequence of Events A- deposition of A B- deposition of B
C- deposition of c
D- intrusion of D
E- Extrusion of E
F- deposition of F

8. Rock Correlation
Outcrop- exposed rock layers (strata)

9. Index Fossils Geologic time marker
3 things that make a good index fossil:
Easily recognized
Lived for a short geologic time
Wide spread geographically

10. Volcanic Ash Falls Wide spread geographically
Can be good time markers because it is per event

11. Unconformity A gap on geologic time Missing part of the rock sequence
Caused by extensive erosion

12. Faults, Folds, Tilting
Movements are younger than the rocks they displace

13. Overturned
When older rocks are found on top of younger rocks due to extreme crustal movement

14. Sequence of Events Practice pg 109
Determining Which is older wkst
Sequence of Events Lab

15. Absolute Time Radioactive dating Absolute age
Nothing affects decay rate
Decay product
Isotopes- unstable elements

16. Half life
The amount of time it takes for one half of the isotope to decay

17. Decay Product
What the isotope becomes

18. A continuous process wkst
Radioactive decay data wkst

19. Evolution
Natural selection: where an organism has a specific trait that aides in their survival.
Changes occur very slowly over a long period of time
Survival of the fittest?

20. Geologic Time Scale
Describes the events that have take place in the history of earth
Based upon the fossil record
Broken up into eons, eras, periods, and epochs

21. Geologic history timeline
Geologic history of NY lab