Scientists define the physical layers of Earth in two ways.  One is by their_____  composition and by their_______ properties.

Chemical compostition and physical properties.

(see chapter 7:section 1. page 190)

Crust,

Mantle

Inner & Outer Core

(Chpt. 7 Sec. 1 pg. 190)

A compound is a substance composed of two or more elements.

(Chpt 7: sec 1, pg 190)

The layers of the crust are less dense because heavier elements (metals) are pulled toward the center of the Earth by gravity, and elements of lesser mass are found farther from the center. 

(Remember the center of the Earth is a solid ball of iron and nickle).  Chpt 7: sec 1 pg 190).

CRUST

Chpt 7 Sec 1 pg 190

continental and oceanic

(Chpt 7 sec 1 pg. 190)

oxygen, silicon, and aluminum

iron, calcium, and magnesium

Chpt 7 sec.1 pg. 190

mantle

chpt 7 sec 1 pg 191

lithosphere- tectonic plates

asthenosphere- slow moving rock layer

mesosphere- part of mantle 

outer core

inner core

Chpt 7 sec 1 pg. 192-193

lithosphere

chapt 7 sec 1 pg 192-193 (diagram)

tectonic plates

chpt 7 sec 1 pg 192-93.

asthenosphere

chpt 7 sec 1 pg 192-93

Mesosphere

Chpt 7 sec 1 pg 192-93 (see diagram)

liquid outer core and a solid inner core.  (Made of nickle and iron)

Chpt 7 sec 1 pg 192-93 (see diagram)

tectonic plates

chpt 7 sec 1 pg. 194

jigsaw puzzle

Chpt 7 sec 1 pg. 194

Scientists have never even drilled through the crust, which is only a thin skin on the surface of the Earth. So, how do they know so much about the mantle and the core and why?

Scientists learn about the mantle and core from earthquakes. 

WHY?  When an earthquake happens, vibrations called seismic waves are produced. Seismic waves travel at different speeds through the Earth. Their speed depends on the density and composition of material that they pass through. For example, a seismic wave traveling through a solid will go faster than a seismic wave traveling through a liquid.

Chpt 7 sec 1 pg. 196

When an earthquake happens, vibrations called _____ ____ are produced.

seismic waves

Chpt 7 sec 1 pg. 196

When an earthquake happens, machines called ______ measure the times at which seismic waves arrive at different distances from an earthquake.

seismographs

Chpt 7 sec 1 pg. 196

Seismologists use the distances and travel times of seismeic waves to calculate the ______ and _____ of each physical layer of the Earth.

density and thickness

Chpt 7 sec 1 pg 196

A seismic wave traveling through a ____ will go faster than a seismic wave traveling through a ______.

solid, liquid

Chpt 7 sec 1 pg. 196

seismic waves, earthquakes

Chpt 7 sec 1 pg. 197

______ is the hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations.

Continental drift

Chpt 7 sec 2 pg. 198

In the early 1900s, this scientist wrote about his hypothesis of continental drift.

Alfred Wegener

Chpt 7 sec 2 pg. 198

______ can be used to explain why fossils of the same plant and animal species are found on continents that are on different sides of the Atlantic Ocean

Continental drift

Chpt 7 sec 2 pg. 198

Scientist Alfred Wegener thought that all of the present continents were once joined in a single, huge continent called _____. 

Wegener called this continent Pangaea (pan JEE uh), which is Greek for “all earth.”

Chpt 7 sec 2 pg. 199

About 180 million years ago Pangaea split into two huge continents called _____ and _____ which in turn divided into the contents known today.

Laurasia and Gondwana

Chpt 7 sec 2 pg. 199

_________are underwater mountain chains that run through Earth’s ocean basins.

Mid-ocean ridges

Chpt 7 sec 2 pg. 200

Places where sea-floor spreading takes place _________.

Mid-ocean ridges

Chpt 7 sec 2 pg. 200

______is the process by which new oceanic lithosphere forms as magma rises toward the surface and solidifies.

Sea-floor spreading 

(As the tectonic plates move away from each other, the sea floor spreads apart and magma fills in the gap. As this new crust forms, the older crust gets pushed away from the mid-ocean ridge).

Chpt 7 sec 2 pg 200

Sea-floor spreading creates new ______at mid-ocean ridges.

oceanic lithosphere

Chpt 7 sec 2 pg 200

Some of the most important evidence of sea-floor spreading comes from ______ recorded in the ocean floor.

magnetic pole reversals

Chpt 7 sec 2 pg 200

When Earth’s magnetic poles change places, it is called a ______.

magnetic reversal

Chpt 7 sec 2 pg. 200

How do scientist know for sure that sea-floor spreading takes place?

Molten rock at the mid-ocean ridges contains tiny grains of magnetic minerals (iron).  When magnetic field (poles)reverses, the iron in the molten rock aligns in the opposite direction.

The new rock records the direction of the Earth’s magnetic field. As the sea floor spreads away from a mid-ocean ridge, it carries with it a record of magnetic reversals. This record of magnetic reversals was the final proof that sea-floor spreading does occur.

Chpt 7 sec 2 pg 201

_____is the theory that the Earth’s lithosphere is divided into tectonic plates that move around on top of the asthenosphere.

Plate tectonics

Chpt 7 sec 3 pg. 202

______ is a place where tectonic plates touch.

A boundry  (All tectonic plates share boundaries with other tectonic plates).

Chpt 7 sec 3 pg. 202

Tectonic plates can _____,_____ or ____ past each other.

collide, separate, or slide

Chpt 7 sec 3 pg. 202

____can occur at all three types of tectonic plate boundaries.

Earthquakes

Chpt 7 sec 3 pg. 202

When two tectonic plates slide past each other horizontally, the boundary between them is a ______ ____.

transform boundary

Chpt 7 sec 3 pg. 202

When two tectonic plates separate, the boundary between them is called a _____ _______.

divergent boundary

Chpt 7 sec 3 pg. 202

______are the most common type of divergent boundary.

Mid-ocean ridges

Chpt 7 sec 3 pg. 202

_____forms at divergent boundaries.

New sea floor

Chpt 7 sec 3 pg 202

The ______ is a good example of a transform boundary.

San Andreas Fault

Chpt 7 sec 3 pg. 202

When two tectonic plates collide, the boundary between them is a _______ _____.

convergent boundary

Chpt 7 sec 3 pg. 203

The three types of convergent boundaries are ______, ______, and _______.

continental-continental boundaries

continental-oceanic boundaries

oceanic-oceanic boundaries

Chpt 7 sec 3 pg. 203

When a plate with oceanic crust collides with a continental plate, the denser oceanic crust ______.

sinks into the ansthenosphere

Chpt 7 sec 3 pg. 202 (see diagram)

_______ ______ describes the location where old oceanic crust gets pushed into the asthenosphere then remelted and recycled.

Subduction zone

Chpt 7 sec 3 pg. 202 (see diagram)

At divergent boundries, ______ rises to fill in gaps between plates.

magma

Chpt 7 sec 3 pg. 202

At mid-ocean ridges rising _______ cools to form new _____ _____.

magma,  sea-floor

Chpt 7 sec 3 pg 202 (see diagram)

When two continental crust plates collide they _____ and ____ with causes them to ______.

buckle and thicken causing them to push upward

Chpt 7 sec 3 pg. 202

(see diagram)

At _______ boundaries plates slide past one another.  The irregular edges of the plates cause jerking and grinding which in turn causes _______.

transformation,  earthquakes

Chpt 7 sec 3 pg. 202 (see diagram)

What causes the motion of tectonic plates?

Movement occurs because of changes in density within the asthenosphere.

These density changes are caused by the outward flow of thermal energy from deep within the Earth. When rock is heated, it expands, becomes less dense, and tends to rise to the surface of the Earth. As the rock gets near the surface, the rock cools, becomes more dense, and tends to sink.

Chpt 7 sec 3 pg. 204

______ happens when hot rock from deep in the earth rises and cooler rock sinks.

Convection

Chpt 7 sec 3 pg. 204 (see diagram)

_____ causes lithosphere to move sideways away from mid-ocean ridges.

Convection

Chpt 7 sec 3 pg. 204 (see diagram)

Because of ____ _____ the oceanic lithosphere slides downhill due to the force of gravity.

Ridge push

Chpt 7 sec 3 pg. 204 (see diagram)

Tectonic plate movements are very slow and measured in ______ per year.

centimeters

Chpt 7 sec 3 pg 205

_____, ______, and _____ are three possible driving forces of plate tectonics.

Ridge push, convection, and slab pull

Chpt 7 sec 3 pg. 205

Boundaries between tectonic plates are classified as ____,_____ and _____.

convergent, divergent, or transform

Chpt 7 sec 3 pg. 205

global positioning system (GPS)

Chapt 7 sec 3 pg. 205