DO NOW Grab a textbook, turn in progress reports if

you have them

Why do we have a magnetic field around our planet?

What does the lithosphere float on top of?

What is the difference between the outter core and the inner core?

OBJECTIVE SWBAT- describe the theory of continental

drift and plate tectonics

Identify the 7 major plates and the 7 minor plates

Identify the three plate boundaries and what feature is associated with each plate boundary

TESTING PLATE TECTONICS

Sections 9.4 and 9.5

GUIDED NOTES Your task- Use your textbooks to fill out the

first column of the guided notes

233

EARTH’S STRUCTURE

Earth’s interior consists of three major zones defined by its chemical composition:1. Crust2. Mantle3. Core

CRUST 1. Thin, rocky outer layer of Earth 2 types: continental and oceanic

Continental crust is about 5-47 miles (very thick) Consists of many rock types

Oceanic crust is about 4 miles thick (thin) Composed of igneous rocks

MANTLE1. Solid, rocky shell that extends to a depth of

about 1800 miles2. Divided into Upper Mantle& Lower Mantle3. Largest layer of the Earth

CORE1. Made mostly of iron-nickel alloy2. Very hot3. Inner core

Radius of about 760 miles Due to the extreme pressure, the material is

solidOuter core

Liquid layer is about 1400 miles thick Earth’s magnetic field is generated from the flow

of metallic iron

LITHOSPHERECrust and upper most part of the mantleRigidASTHENOSPHERE• Beneath lithosphere• Soft and flexible

CONTINENTAL DRIFT HYPOTHESIS A German scientist and meteorologist,

Alfred Wegener, proposed a hypotheses: Pangaea : The continents had once been joined

to form a single supercontinent, Pangaea meaning all land

EVIDENCE FOR CONTINENTAL DRIFT The Continental Puzzle

Similar coastlines on opposite sides of the ocean Continents fit together, like a puzzle

Matching Fossils Fossil organisms found on different landmasses

Rock Types and Structures Several mountain belts end at one coastline and

reappear on a landmass across the ocean○ Appalachian Mountains in US, ending off the coast of

Newfoundland (Figure 4 on page 251) Ancient Climates

Glacier evidence, Figure 5 on page 252

MATCHING MOUNTAIN RANGES

GLACIER EVIDENCE

A NEW THEORY EMERGES… Wegener could not provide an explanation of exactly

what made the continents move Data on earthquake activity and Earth’s magnetic field

became available By 1968, these findings

led to a new theory,plate tectonics

PLATE TECTONICS THEORY The upper most mantle and crust, behave as a

strong, rigid layer known as the lithosphere Lithosphere is divided into plates, which move and

continually change shape and size (move about 5cm per year)

7 major plates (pages 256-257, Figure 8) The grinding movements of the plates generate

earthquakes, create volcanoes and deform masses of rock into mountains

PLATE BOUNDARIES Convergent

Two plates move together Divergent

Two plates move apart Transform (fault)

Two plates slide past each other

FEATURES ASSOCIATED WITH BOUNDARIES Volcanoes- Subduction zones (convergent

boundaries)

Mountain ranges – (convergent boundaries)

Sea floor spreading – Ocean Ridge (divergent boundaries)

Earthquakes – (transform)

VOLCANO

MOUNTAIN RANGE

SEA FLOOR SPREADING

PLATE TECTONICS http://www.youtube.com/watch?v=

ryrXAGY1dmE

TESTING PLATE TECTONICS Paleomagnetism

When a rock forms, it becomes magnetized in the direction parallel to Earth’s existing magnetic field

Normal polarity – when rocks show the same magnetism as the present magnetic field

Reverse polarity – when rocks show the opposite magnetism as the present magnetic field

EVIDENCE FOR PLATE TECTONICS The discovery of

strips of alternating polarity, which lie as mirror images across ocean ridges, is among the strongest evidence of seafloor spreading

ANIMATION http://earthguide.uc

sd.edu/eoc/teachers/t_tectonics/p_paleomag.html

DIAGRAM Draw a diagram and label 1) sea floor spreading happening at a mid

ocean ridge 2) Subduction happening between oceaninc

and continental crust near a trench 3) A mountain range along a coastline

** Label what type of boundary is associated with each feature (transform, convergent, divergent)

EXIT TICKET

EVIDENCE FOR PLATE TECTONICS Earthquake Patterns

Scientists discovered a close link between earthquake origins and ocean trenches

Earthquakes occur only within the subducted slab of oceanic lithosphere

Ocean Drilling Youngest oceanic crust is at the ridge crest, the oldest crust is at the continental margins Data on the ages of seafloor sediment confirmed the seafloor spreading hypothesis

EVIDENCE FOR PLATE TECTONICS Hot Spot (Volcanic

area) A concentration of

heat in the mantle produces magma, which rises to Earth’s surface creating volcanic mountains

Hot Spot evidence supports the theory that plates move over Earth’s surface

Hawaiian Islands

CAUSES OF PLATE MOTION Convection occurring in the mantle, specifically

asthenosphere, is the driving force for plate movement Convective flow is the motion of matter resulting from

changes in temperature Warm, less dense material rises Cool, more dense material sinks

The unequal distribution of heat within Earth causes convection in the mantle, which drives plate motion

CAUSES OF PLATE MOTION Slab-pull occurs when the cool, dense

oceanic crust sinks into the mantle and “pulls” the lithosphere along

Ridge-push causes oceanic lithosphere to slide down the sides of the oceanic ridge under the pull of gravity

EARTHQUAKESEarthquakes: The

shaking of the earth’s crust caused by the release of energy.

A. focus: point within Earth where the EQ begins

B. epicenter: location on earth’s surface directly above focus

C. faults: 1 cause of EQ’s, large fracture in crust

CAUSES OF EARTHQUAKES