Theory of Plate Tectonics

What Wegner knew… Continents fit together like a puzzle Similar fossils found on different continents A continent has gone through climate changes due to its location on Earth Similar rock formations on different continents

What Wegner Couldn’t Prove… Cause or force that moved massive continents apart and together Areas where new crust was formed and old crust destroyed Edges of Plates  Where are they?

Objectives Identify and explain the force that drives plate motion…and pretty much everything else in the universe Describe the 3 different types of plate boundaries AND the landforms associated with each Describe seafloor spreading Know the special case of hot spots

Review from Yesterday

What are 5 layers of the Earth? Inner Core Outer Core Mantle Asthenosphere Lithosphere

What are the two types of crust (lithosphere)? Continental Crust Oceanic Crust

The Driving Force Demo

Why does anything hot Rise? Molecules or materials become LESS dense when they are hotter. Why? Higher Temperatures  More energy of Molecules  Molecules are spread out = LOWER DENSITY Vice Versa Lower density materials float on higher density materials = warmer materials will ALWAYS float on cooler materials

What is Convection? Transfer of Heat Energy from Hot  Cold when materials are in contact with each other Cool Magma Sink Cooled Magma Reheats Hot Magma Rises Earth’s Core

3 - Types Plate Boundaries Convergent = Collision of Plates Divergent = Plates Moving Apart Transform = Plates Slipping Past Each Other

Convergent Boundary

2 Effects of Convergent Boundaries Mountain Building A) Oceanic to Oceanic Crust Collision B) Continental to Continental Crust Collision Subduction Zone with Volcanic Mountain Chains Oceanic to Continental Crust Collision *Crust is being destroyed at convergent boundaries*

Subduction Zone

Divergent Boundary Sea Floor Spreading

Divergent Boundary Rift Valley

2 Outcomes of Divergent Boundary Sea-Floor Spreading/Mid-Ocean Ridges Crust is being Formed Rift Valleys Depression or Gap in Crust is Formed

Transform Boundary

Outcomes of Transform Boundaries Crust is not being destroyed or created Crust is being deformed  metamorphic rock No Associated Landforms

Case of Seafloor Spreading Rocks Closest to Ridge is youngest; vice versa

Case of Hawaii Hot Spots = where magma bubbles up forming volcanoes

Earthquake and Volcano Pattern

Evidence for Plate Tectonics Continents fit together like a Puzzle Similar Fossils on different continents A continent may have gone through several climates due to its changing position on surface Similar Rock formations on different climates Seafloor Spreading/Mid-Ocean Ridges/Subduction Zones Plate Boundaries  Earthquake and Volcano Patterns Heat generated inside drives Convection Current

In Review Plates Move due to Convection Landforms Mountains Trenches Mid-Ocean Ridges Rift Valleys Volcanoes 3 types of boundaries Earth’s Crust gets recycled Earthquakes Hot Spots

At this point… Evidence used for Continental Drift and Plate Tectonics Structure of Earth Continental vs Oceanic Crust How Convection Works Why Convection Works Like It Does Describe the 3 types of plate boundaries Landforms associated with each boundary