1. Unit 2: Relative Dating - Part 2
Earth Systems 3209
Unit 2: Relative Dating - Part 2

2. relative dating 6 Major Types: Superposition Horizontality
Cross-cutting relations
Inclusions
Unconformities
Fossils

3. 4. Law of Inclusion fragments (rock fragments)
Pieces of one rock found in another rock must be older than the rock in which they are found.

4. Q1: Identify the inclusions in the diagram Which is older E or D?

5. Q2: In each example which layer is older?

6. Superposition, horizontality, cross-cutting relations and inclusions

7. 5. Unconformities 3 types: Angular Unconformity, Disconformities and
A surface between successive strata (layers) representing a missing interval in the geologic record of time
3 types:
Angular Unconformity,
Disconformities and
Nonconformity

8. *a gap in the rock record.

9. Unconformities – angular unconformity
Older strata (beds of sedimentary rock) dip at an angle different from younger strata above.
Indicates:
A. Pause in deposition
B. Folding and uplifting
C. Period of erosion
D. Renewed deposition

13. Unconformities - disconformities
More common but harder to identify
Is a surface where erosion has occurred but beds above and below are still parallel to one another.

14. Formation of disconformities

15. Unconformities - nonconformity
A boundary between older metamorphic or igneous rock from younger sedimentary rock above.
**Igneous and metamorphic rock form well below the surface.
Indicates:
A. uplift 
B. erosion 
C. Deposition

17. Formation of nonconformity

18. Q3: Name each of the unconformities below:

19. 6. Fossils - Correlation Hand out fossils
Fossils are used to match up rock layers between widely separated areas or between continents
any time period can be recognized by its fossil content.
the matching up of
rock layers from one
area to another.

20. Fossils - Correlation
if there are missing rock layers, you can use fossils embedded in the rocks to tell when each layer was deposited.
*helpful with unconformities*

21. Interpreting and Drawing well-labelled, detailed cross-sectional diagrams (Lab)
in order to do these, rock types need to be correlated based on color, texture, rock types and fossils.
Examples – a key is needed

22. Interpreting and Drawing well-labelled, detailed cross-sectional diagrams (Lab)
Create the following:
Layers in order were laid – sandstone, shale and conglomerate, then these underwent folding. Years of erosion occurred, then a layer of limestone was laid. Finally a basalt dike rose up through the layers.

23. Group work
Practice questions