1. UNIT 5: GEOLOGIC HISTORY

2. AT THE END OF THIS UNIT YOU WILL BE ABLE TO  Calculate the absolute age of a substance based on its decay rate  Correlate rock layers  Create a sequence of events for an outcrop  Obtain information from the geologic timeline

3. LABORATORY ACTIVITIES FOR THIS UNIT:  Matching Rock Layers  Radioactive Decay  Geologic History Timeline  Sequence of events

4. PLEASE ADD THESE TO YOUR TABLE OF CONTENTS IN YOUR NOTEBOOK Unit 5 Geologic History 59-61 Geologic history vocabulary 62 Ages: absolute and relative 63 Radioactive decay: absolute age 64 Radioactive isotopes 65 Matching/ correlation of rocks 66 Order of events

5. NOW TURN TO PAGE 59 AND NUMBER UP TO PAGE 66 On page 59 at the top please write: Unit 5: geologic history vocabulary You will be writing out 19 vocabulary words, you may not need up all 3 pages, but I gave you extra room in case you did.

6. VOCABULARY  Absolute age- the actual age, in years of an event  Relative age- the age of a rock or event in relationship to the age of another rock or event, a comparison  Half life- time required for half of a substance that is unstable to become stable

7. VOCABULARY  Radioactive dating- the use of a radioactive isotope to calculate the absolute age  Radioactive decay- a breakdown of an unstable atom to a stable atom  Carbon 14 dating- dates organic remains only

8. VOCABULARY  Uniformitarianism- the present is the key to the past, what happens now happened then  Superposition- youngest layer is on the top oldest is on the bottom  Original horizontality- rock layers form as horizontal layers

9. VOCABULARY  Unconformity- erosional surface, some layer has been removed, creates a gap in the timeline  Inclusion- older rock within a younger rock  Extrusion- a mass of igneous rock on the surface, exposed to weathering and erosion, contact metamorphism with the layer below only

10. VOCABULARY  Intrusion- a mass of igneous rock formed between layers, contact metamorphism with layers above and below  Contact metamorphism- heat from an igneous rock that changes the rocks around it  Index fossil- used to match layers, must be easy to identify, lived a short time and covered a wide area

11. VOCABULARY  Isotope- a variety of an element with a different atomic mass, unstable, likes to break down  Correlation- matching  Cross cutting relationship- anything that cuts through is younger  Key bed- rock layer that is used to identify an event or geologic age

12. EARTH SCIENCE PICTURE OF THE DAY  http://epod.usra.edu/ http://epod.usra.edu/

13. I. AGES A. Absolute ages: Gives you exact numbers 1. example: your age, the year a car was produced(made) On page 62 of your notebook

14. I. AGES B. Relative age: Comparison of one to another 1. no numbers 2. approximate ages a. I am older than my brothers b. Names of geologic time On page 62 of your notebook

15. II. DETERMINING THE AGES (ABSOLUTE AGE) A. Radioactive decay or half life 1. Amount of time it takes half the sample to decay or break down into a stable isotope. a. paper folding activity On page 63 of your notebook

16. II. DETERMINING THE AGES (ABSOLUTE AGE) B. Radioactive isotopes 1. Carbon -14, organic materials only (living) a. Examples: cotton, teeth, bones, trees, bugs, etc… b. Half life: 5.7 x 10 3 years On page 64 of your notebook

17. LAB: RADIOACTIVE MATERIAL? Everyone needs to wash their hands with soap and water before we start the lab.

18. GEOLOGIC MAP OF NYS Ages Rock names Rock types young old

20. III. MATCHING/CORRELATING LAYERS A. Key beds: covers everything, marks a time when something BIG happened, it is a time marker. 1. Dinosaur extinction: Meteorite impact debris and dust On page 65 of your notebook

21. III. MATCHING/CORRELATING LAYERS B. Other ways to match layers 1. Fossils, animal remains 2. unconformities: erosional surfaces 3. rock and mineral types On page 65 of your notebook

22. Where is the unconformity?

24. IV. ORDER OF EVENTS A. Principles that we use 1. no process has changed since the earth formed is called Uniformitarianism 2. Sediment layers are always deposited flat, Original Horizontality On page 66 of your notebook

25. Original Horizontality See the flat layers?

26. IV. ORDER OF EVENTS A. Principles that we use 1. Oldest layers are on the bottom, the youngest are on the top, Superposition On page 66 of your notebook

28. What layer is the oldest? What layer is the youngest? What came first, the Brunswick sandstone or the Palisades sill?

29. IV. ORDER OF EVENTS A. Principles that we use 2.Since the layers are deposited flat when the layers do not match, something must have happened after they were deposited, Cross Cutting Relationship a. Faults, Folds, Intrusions, Extrusions, etc…. On page 66 of your notebook

30. The horizontal layers had to be deposited first This was intruded through the layers that were there first. This is called INTRUSION

31. See how the layers are folded over each other

32. This is extreme folding that is found often in mountain areas

33. More folded layers

34. The sandstone layers match and the fault cuts through them so the layers had to be there first

35. As the pressure on the layers increases the folds can only handle so much stress and they break creating a fault.

36. Look for the faults first! Match the layers across the faults.

37. This is an “A”nticline or fold in the rocks