Topic: Relative DatingTopic: Relative Dating
What is the usual order these What is the usual order these meals are eaten during the day?meals are eaten during the day?
A C
BD
Typical OrderTypical Order
C
B
A
D
Relative DatingRelative Dating: :
----
Principles of Relative Principles of Relative DatingDating
The layers and jagged rocks of the reef, Capitol Reef , Utah
Orange Layer
Red Layer
Green Layer
1.1.Principle of Superposition Principle of Superposition – –
Superposition in the Grand CanyonSuperposition in the Grand Canyon
2) 2) Original Horizontality Original Horizontality --
Normal faults are nicely exposed at several points within the canyon walls. Red Rock Canyon State Park near Mojave, California
3. 3. The Law of Deformed Strata:The Law of Deformed Strata: --
Folded Strata
Normal Strata
Faulted Strata
Tilted Strata
4. C4. Cross-cutting relationships-ross-cutting relationships---
Intr
usi
on
Before the lava & magma cools Before the lava & magma cools
After the magma and lava coolsAfter the magma and lava cools
Igneous Intrusions causes Igneous Intrusions causes Contact Contact MetamorphismMetamorphism
Contact metamorphism with pegmatite Orchard Beach, Bronx
Hot Magma touches surrounding rocks
HHeeaatt
Granite Intrusion
Pre-existing rock
Conta
ct m
etam
orph
ism
Conta
ct m
etam
orph
ism
Pre-existing rock
Contact Contact MetamorphismMetamorphism: : shown by shown by hachure marks hachure marks
5. 5. Included fragments:Included fragments: - -
6) Unconformities6) UnconformitiesBuried erosional surface -Buried erosional surface -
Limestone
UpliftUplift
WeatherinWeathering & Erosiong & Erosion
Curved, wavy surface shows erosion
UnconformityUnconformity
Layers are formed according to superposition.Layers are formed according to superposition.
Something happens to uplift the area folding, Something happens to uplift the area folding, faulting, etc.faulting, etc.
Erosion wears away the uppermost layersErosion wears away the uppermost layers
Area submerges and deposition begins again.
Here’s the unconformity
Final Question: Final Question: Place the letters in order from oldest Place the letters in order from oldest
to youngestto youngest– --– --– --– --– --– --– --
Sequence 1: Uplift & ErosionSequence 1: Uplift & Erosion
1.1. Limestone Limestone depositeddeposited
2.2. Sandstone Sandstone depositeddeposited
3.3. Shale DepositedShale Deposited
4.4. UpliftUplift
5.5. ErosionErosion
Sequence 2: FaultingSequence 2: Faulting1.1. --
2.2. --
3.3. --
4.4. --
Sequence 3: FoldingSequence 3: Folding1.1. --
2.2. --
3.3. --
4.4. --
Sequence 4: Igneous IntrusionSequence 4: Igneous Intrusion
1.1. --
2.2. --
3.3. --
4.4. --