the relative age of rocks 10-2. place in order from youngest to oldest a b c d ef
TRANSCRIPT
Relative Dating
Used to determine the order of events and age compared to surrounding materials
Can not tell exact age
Law of Superposition
In horizontal sedimentary rock layers, the oldest layer is at the bottom. Each higher layer is younger than the layers below it.
Igneous Rock Clues
- Forms when magma or lava hardensExtrusion – lava that hardens on the
surface-an extrusion is always younger
than the extrusion below it
Igneous Rock Clues
Intrusion – magma pushes into bodies of
rock then cools and hardens
- an intrusion is always younger than
the rock layers around it
Intrusion
Intrusion
A mass of igneous rock below the surface is called an Intrusion. It is always younger than the rock layers around and beneath it.
Fault
A fault is a break in the Earth’s crust. A fault is always younger than the rock it cuts through. It makes the layers not line up.
Unconformities
Occur when there are missing layers in the rock record
1) Erosion of existing layers
2) No new deposition for a period of time (disconformity)
Angular Unconformity – tilted rock layers meet horizontal rock layers indicating gaps in rock record
Unconformity
The surface where new rock layers meet a much older rock surface beneath them is called an unconformity. It is a gap in the geologic record.