1. Relative Dating
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2. Warm-Up Q).What Kind of belief does the following statement support:
“Major geologic changes in the past happened at the same rate as they do today- GRADUALLY”
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4. What does the word RELATIVE mean?
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5. Engage
When you look at a rock or fossil you might think “How old is this?” (if you’re cool)
Scientists have a way of using clues found in the rock layers to estimate how old a rock is.
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6. Stratigraphy
Stratigraphy:The study of the rock layers and how they relate to one another.
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7. Relative Dating
The relative age of a rock is its age compared to the ages of other rocks.
You use this method in your daily life all the time!!
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8. Who is older?
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9. Relative Dating
You don’t know the exact age of the ladies in the photos, however, you knew based on clues you have learned that the picture on the left was older.
The relative age of a rock does NOT provide its absolute age
The absolute age of a rock is the number of years since the rock formed.
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10. Which is older?
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11. Order the pictures from youngest to oldest
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12. Let’s see what you can do?
Which Rock is the oldest?
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13. Which is older?
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14. Which is older?
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15. Which is older?
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16. Which is older?
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17. Which is older?
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18. Relative Dating
Scientists use many clues to determine which rocks are older or younger in rock structures
Law of Original Horizontality
Law of Superposition
Law of Crosscutting relationships
Law of Inclusion
Law of Faunal succession
Index Fossils
Unconformities
Disturbances
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19. Law of Original Horizontality
Sedimentary rock are originally deposited in horizontal layers.
Forces of the Earth (uplift, faults, erosion, tectonic plates) disturb them over time.
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20. Law of Original Horizontality
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22. Law of Superposition
The Oldest rock layer is on the bottom and the youngest rock layer is on the top in an undisturbed rock sequence.
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23. Which Rock layer is the oldest?
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24. Law of cross-Cutting Relationships
Any feature that cuts across a body or segment of rock is YOUNGER than the body of rock it cuts through.
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25. Law of cross-Cutting Relationships
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26. Law of cross-Cutting Relationships
An intrusion is younger than the rock layer it cuts through.
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27. Law of cross-Cutting Relationships
A fault is younger than the layers that it breaks.
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28. Law of Inclusion
The body of rock that contains inclusions of preexisting rock is younger than the rocks that the inclusions came from.
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29. The oldest rock in this picture is rock layer ___________
The youngest rock in this pictures is rock layer ___________
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