1. Intrusions, Inclusions, Cross Cuts
intrude
include

2. Intrusions, Inclusions, Cross Cuts
- liquid rock (magma) under the Earth’s surface pushes up
into any cracks or spaces
may take millions of years
- small or as big as mountains…. Sierra Nevadas, Devils Tower

3. Intrusions, Inclusions, Cross Cuts
- liquid rock (magma) under the Earth’s surface pushes up
into any cracks or spaces
may take millions of years
- small or as big as mountains…. Sierra Nevadas, Devils Tower

4. Intrusions, Inclusions, Cross Cuts
- liquid rock (magma) under the Earth’s surface pushes up
into any cracks or spaces
may take millions of years
- small or as big as mountains…. Devils Tower, Sierra Nevadas
a piece of geological detritus that becomes
incorporated into another rock or sediment
‘clast’ in sedimentary rock
‘xenolith’ in igneous rock

5. The Principle of Intrusive Relationships
- invading igneous rock is always younger than the rock it intrudes
- several types of intrusions:
sill – an intrusion that happens between layers
laccolith – a more prominent sill

6. The Principle of Intrusive Relationships
- invading igneous rock is always younger than the rock it intrudes
- several types of intrusions:
sill – an intrusion that happens between layers

7. The Principle of Intrusive Relationships
- invading igneous rock is always younger than the rock it intrudes
- several types of intrusions:
dike – an intrusion that cuts across pre-existing rock

8. The Principle of Intrusive Relationships
- invading igneous rock is always younger than the rock it intrudes
- several types of intrusions:
dike – an intrusion that cuts across pre-existing rock

9. The Principle of Intrusive Relationships
- invading igneous rock is always younger than the rock it intrudes
- several types of intrusions:
batholith – a large irregular discordant intrusion

10. The Principle of Intrusive Relationships
- invading igneous rock is always younger than the rock it intrudes
- several types of intrusions:
batholith – a large irregular discordant intrusion

11. The Principle of Intrusive Relationships
- invading igneous rock is always younger than the rock it intrudes
- several types of intrusions:

13. The Principle of Inclusions
any inclusion is older than the rock or sediment into which it has been included

17. Cross Cuts any geologic feature that cuts across a rock or sediment
could be faults, intrusions or erosion
The Principle of Cross Cutting
any cross cut must be younger than the rock or sediment it cuts across.

18. Sequence
erosion
E fault (normal)
D (intrusion) A B C
(oldest)

19. erosion
F (normal) E
D (intrusion: dike) C
erosion (angular unconformity, nonconformity)
B (intrusion: batholith)
A (reverse)
brown/gray layers, folding
(oldest)

20. Geo 4&5 Practice 7
Geo 4&5 Practice 8 (challenge)

23. If there is an unconformity write ‘unconformity’ (+ which one).
If there is folding write ‘folding’ (+ which type).
If there a fault write ‘fault’ (+ which type).

24. If there is an unconformity write ‘unconformity’ (+ which one).
If there is folding write ‘folding’ (+ which type).
If there a fault write ‘fault’ (+ which type).

25. If there is an unconformity write ‘unconformity’ (+ which one).
If there is folding write ‘folding’ (+ which type).
If there a fault write ‘fault’ (+ which type).

26. If there is an unconformity write ‘unconformity’ (+ which one).
If there is folding write ‘folding’ (+ which type).
If there a fault write ‘fault’ (+ which type).

27. Sequence