Warm-Up1. P. 229 To describe the sequence and

length of changes in the Earth, scientists have developed a _______ _______ _______.

1.Geologic time scale

2. P. 229 A ________ __________ represents a timeline of Earth's history.

1.Geologic column

3. P. 229 Are the oldest or youngest rocks found at the bottom of a geologic column?

1.Oldest

Objectives• Understand how earth formed billions of years ago

• Differentiate between the different layers of the earth

• Earth's Formation

Early Earth

•Earth began as gas and dust

•Gravity from the sun made particles collide and stick together –called Accretion

•The earth was born

Early Earth (4 to 4.5 billion years ago)• The earth remained very hot for millions of yearsFrequent volcanic activity

There is no life on the planet yet

Atmosphere was made up of mainly hydrogen, helium, and methane.No oxygen

Cooling Process• Earth began to slowly cool

• Landforms grew larger

• Bacteria began living on the planet and began producing oxygen that would form our atmosphere

• Clouds were able to form and the rain cooled the hot lava and made our continents and oceans

Earth’s Layers

• Formation of the layers As the earth cooled, the

denser materials moved toward the core

The less dense material moved toward the crust

Lithosphere (crust)

•Rigid

•Broken up into tectonic plates

•Thinnest of the 4 main layers3 to 30 miles thick

Asthenosphere (mantle)

• “Plastic” like Flows like putty (not rigid,

but doesn’t flow like water)

• The layer that tectonic plates “float” on

• 1,800 miles thick

Convection Zones

• Pockets within asthenosphere (mantle)

• Hot magma rises towards crust, cools, and sinks back down Same idea as a lava lamp!

• Driving force of plate tectonics

Inner/Outer Cores• Liquid outer core

Made up of liquid Iron and Nickel

1,400 miles thick

• Solid inner core Made up of solid Iron and

Nickel

800 miles thick

• Rotation of the two cores is why we have a magnetic field

Warm - Up

•P. 272 What causes tectonic plates to move?Convection

•P. 275 ____________ is the process by which continents break apart.Rifting

•P. 277 _____________ climates are a result of past movements of tectonic plates.Modern

Cool Down