SME
Grade 12 Science · Problem type
Putting rock events in order
Use this for “A dike cuts three layers and stops at an eroded surface under a lava flow. Which happened first?”
Put in order
A cliff has limestone at the bottom, then shale, then sandstone. A dike cuts all three and ends at an eroded surface under a lava flow. Put the events in order.
1
?
2
?
3
?
4
?
5
?
6
?
Assumptions
•
Superposition: lower layers are older unless folded or overturned.
•
Cross-cutting: a rock is younger than what it cuts.
•
An eroded surface is a gap in the record.
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