What are the 2 methods of dating in Geologic Time?

__________ and _______________ studied features preserved in rocks & present-day geologic processes.

Why is Sir Charles Lyell important?

Uniformitarianism

Who formulated these principles?

Who expounded upon these principles?

Seven principles of relative dating: 1) .2) .3) . 4) .5) .6) .7) .

Original horizontality

Superposition

Grand Canyon, Ariz.

Lateral continuity

Inclusions

In A & C, granite contains inclusions & is younger than the inclusions.

• In B, sandstone is younger than the granite b/c it contains inclusions of granite.

A B

CWisconsin

Cross-cutting relationships

Ontario, Canada Castaic, Ca

Principle of deformed rocks

What are conformable contacts?

Unconformities

What is a hiatus?

Types of Unconformities

What is a Disconformity?

• How are disconformities recognized?

What is an Angular unconformity?

James Hutton = 1st to recognize & understand the significance of an angular unconformity

Siccar Point, Scotland

What is a Nonconformity?

What is correlation?

Why do geologists use correlation?

Factors:

What are Key beds?

Why are fossils important?

What are Index fossils?

• What is Faunal succession?

Absolute-Dating

• ___________________________ discovered radioactivity in 1903.

• Radiometric dating

• Radioactivity

• Isotopes

Radioactive decay

Alpha decay

Beta decay

Electron capture

Half-Lives

Geologic Time Scalewww.acs.appstate.edu/~hagemans/timescale.html

How was the Geologic Time Scale Developed?

Can sedimentary rocks be dated radiometrically? Explain.

How are they dated?