Chapter 10, Section 2

Standards 3b. Students know the principal structures that form at the 3 different kinds of plate boundaries.

Objective 1 Summarize the theory of plate tectonics.

Objective 2 Identify and describe the 3 types of plate boundaries.

Objective 3 List and describe 3 causes of plate movement.

Assessment Flap Book, Chapter Test

Review Daily Bellwork, Science Starters, Standards Practice

Chapter 10, Section 2

Key TermsCreate a flashcard for each of the following terms (found on p.247 in your text book).Plate tectonicsLithosphereAsthenosphereIf you finish early, study your flashcards!

Plate Tectonics• The theory of Continental Drift led to the theory of PLATE

TECTONICS.• PLATE TECTONICS explains how large pieces of the lithosphere,

called plates, move and change shape.• Earth’s crust and the rigid, upper part of the mantle =

LITHOSPHERE. This is the thin outer shell of Earth (like an Egg shell).

• The lithosphere is broken into several pieces called TECTONIC PLATES.

• The TECTONIC PLATES ride or float on the ATHENOSPHERE (part of the Earth’s mantle that is flowing slowly).

Earth’s Crust• OCEANIC CRUST = dense, made of

iron and magnesium-rich rock.• CONTINENTAL CRUST = low density,

made of rock rich in silica.• Both kinds of crust are always

moving with the tectonic plates they are riding on.

Tectonic Plates• 15 major tectonic plates.

Earthquakes and Volcanoes• Frequent earthquakes in an area are

evidence the 2 or more tectonic plates meet in that area.

• Many volcanoes form from plate motion and help scientist identify plate boundaries.

Quick Check!!1. The upper and hard part of the Earth’s mantle is called the

______________________.2. The two types of crust are continental and ____________.3. Scientists have identified about ______ major tectonic plates.4. Name one plate:

_________________________________________________________________________________________________________________________________________________________________________________

Types of Plate Boundaries• Most of the dramatic changes in Earth’s

crust---Volcanoes and Earthquakes---occur at Plate Boundaries.

Divergent Convergent

Transform

Divergent Boundaries• 2 plates move away from each other.• Magma from the athenosphere rises to

the surface as the 2 plates move apart, the magma cools and creates new oceanic lithosphere(sea-floor spreading).

Convergent Boundary• 2 plates collide• 3 types of Collisions

Types of CollisionsOceanic Lithosphere vs. Continental• Oceanic is denser so it sinks under the continental lithosphere• Called a SUBDUCTION ZONE• Deep-ocean trenches and Volcanoes form at SUBDUCTION ZONES

Continental vs. Continental Lithosphere• Neither plate subducts• Colliding edges crumple and thicken causing uplift that forms large

mountain ranges.

Oceanic vs. Oceanic Lithosphere• One plate subducts under the other • Deep ocean trench forms• Magma rises to form and ISLAND ARC, or chain of Volcanic Islands

Transform Boundaries• 2 plates slide past each other horizontally• The edges of the plates scrape and jolt

along each other. This motion is felt as Earthquakes.

• No Magma is produced

Summary—Plate BoundariesDivergent Plates moving away from each

other to form rifts and mid-ocean ridges

North American and Eurasian plates at the Mid-Atlantic Ridge. Red Sea.

Convergent Plates moving toward each other and colliding to form ocean trenches, mountain ranges, volcanoes, and island arcs

South American and Nazca plates at the Chilean trench along the west coast of South America. Himalyan mountains, Japan.

Transform Plates sliding past each other while moving in opposite directions

North American and Pacific Plates at the San Andreas fault in California.

Quick Check!!1. Name the 3 types of plate boundaries:

____________________________________________________________________________________________________________

2. San Andreas fault is an example of a _________ boundary.

3. 2 plates moving apart is a _________ boundary.

4. Mid-Atlantic Ridge is causing South America and _______ to spread apart.

Causes of Plate Motion

Mantle

ConvectionRidge Push

Slab Pull

Mantle Convection1. Heat from the Earth’s core heats the material in

the Mantle.2. The heated material expands and becomes less

dense therefore rising around the cooler, denser material above it.

3. This cycle continues, this is called CONVECTION.

4. Convection currents cause the tectonic plates above it to move.

Plate Tectonics Video Clip

Assessment Make a 3-Flap Book showing each of the

types of plate boundaries. For each flap include:

--Definition/Description--Drawing--Real World Example

Daily Quiz