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. --