Earth’s Age + Evidence

WARM UP1) Ch 2A Diagnostic Test

2) Section Quiz: 2.2A

Notes Tips and Tricks

• Anything in yellow PLEASE write down on your notesheet

• Pictures and diagrams are great things to also draw to help you remember vocab and ideas!

• Underline or bold words that are underlined or bold in PowerPoint BECAUSE THEY ARE IMPORTANT!

How old is the Earth?

Earth is around 4.6 BILLION years old.

BIG QUESTION:

HOW DO WE KNOW HOW OLD THE

EARTH IS?

BIG ANSWER:

Everything coming up provides an

answer to the BIG QUESTION!

Law of Superposition

• Law of Superposition– •Under normal conditions, the layers of sediment get older the deeper you get

Law of Superposition

• Just like a layered cake…you put the bottom layer down first,

so it is the “oldest” and

you fill in each layer on

top of it!

Law of Superposition

• OR the laundry you put in the laundry basket every day!

• Monday’s clothes are the

“oldest” and each day gets

put on top of that!• Draw a laundry basket with

clothes to illustrate the concept!

We Have a Problem…

• 2 things can mess up the

Law of Superposition:

1 – intrusion

2 – unconformity

Intrusion

• A intrusion is younger than any other rock layer it cuts through.

intrusion

Unconformity• Unconformity-

•A break or an irregularity in the geologic time sequence

•A time when no sediment was preserved because it eroded away before it was covered by more sediment OR the ground shifted.

Unconformity

Unconformity

Law of Superposition Practice

Law of Superposition Practice

• This shows the

Law of Superposition,

but what else does it

show?

NEXT……

What is This?

Fossils• Fossil – traces or remains of living

things from long ago

• Index Fossils – fossils that are used as a “reference” to date other fossils

• EX: 8th Gr SC Book

Index Fossil Practice

Relative Age• Relative Age - the age of an event or

object in relation to other events or objects

–Use words like older, younger, around the same time, etc…EX: My sister is older than me.

Absolute Age• Absolute Age - The actual age of an

event or object– Use techniques to figure out actual age

• Radioactive dating, carbon dating

Lived:

1 million years ago

2 million years ago

3 million years ago

4 million years ago

EXAMPLE:

• Relative dating

VS.

Numerical dating

Questions??

“SILENT STATIONS”