Section 1: Earth’s InteriorWho Studies Earth’s Interior?

GeologistsScientists who study the forces that make and

shape planet Earth.

They study the processes that create Earth’s

features and search for clues about Earth’s

history.

What kind of evidence do scientists use to learn about the interior of the earth?

Direct vs. IndirectDirect evidence: from rock samples.

Scientists drill up to 12 km into the earth. Forces

blast rock from as deep as 100 km.

Indirect evidence: from seismic waves

How do scientists study the Earth? To reach the Earth’s core you would have to travel over 6,000

km (3,728 miles)!

Scientists record Seismic Waves – a vibration that travels

through Earth carrying the energy released during an

earthquake Types of seismic waves –

P waves – travel through crust (6km/sec) and mantle (8km/sec)

S waves – will not travel through liquidhttp://aspire.cosmic-ray.org/labs/seismic/seismic.swf

What is the Earth’s structure?

The Crust The Mantle

Lithosphere Asthenosphere

The Core Outer Core

Inner Core

                                                    

What is the structure of the crust? A layer of rock that forms the

Earth’s outer skin including the

rock under the ocean Two types of crust:

Continental Crust

Granite – less

dense crust

Oceanic Crust

Basalt – more dense rock

What is the structure of the mantle? Two major parts:

Lithosphere – upper part of

crust and mantle together;

floats on top of the asthenosphere

Asthenosphere –

softer than the mantle due to

increasing temperature and pressure

The mantle is nearly 3,000 kilometers thick! (1,864 miles)

What is the structure of the core? Two parts

Outer Core – liquid; behaves like a thick liquid; forces the solid inner core to

spin causing Earth’s magnetic field

Inner Core – solid; extreme

pressure squeezes the atoms of

iron and nickel so that they cannot spread out to become liquid

Inner core and outer core are just

slightly smaller than the moon

Chemical Layers Physical Layers

Section 2: Convection and the Mantle How does Heat transfer?

Radiation – heat transfer

through empty space; ex.

sunlightConduction – heat

transfer through direct contact

Convection- heat

transfer by movement

of heated fluids

How do convection currents affect the Earth?

Heating and cooling a fluid changes its

density; warmer fluids have a lower density and

float; colder fluids have

a higher density and

sink

Section 3: Drifting ContinentsWere the continents once together?

Alfred Wegener hypothesized that all

the continents had moved from a

supercontinent known as Pangaea.

What is the evidence for Wegener’s idea?

Evidence of Continental Drift:

Landforms – similar mountain ranges

Fossils – similar fossils of a fernlike plant existed on both continents

Climate – tropical pl ant fossils found in cold climates

Section 4: Sea-Floor SpreadingWhat is happening in the ocean?

Using sonar scientists

discovered mountains

under the ocean The longest chain of

mountains in the world is

under the ocean and is

known as the Mid- Ocean ridge!

Side-scan sonar locates missing plane

Courtesy of NOAA.

Side-scan sonar image of the remains of the submarine USS O-9 (SS-70) off the Isle of Shoals, New Hampshire in more than 400 feet of water.Courtesy of NOAA.

What is sea-floor spreading? Harry Hess suggested that

at the mid-ocean ridge

molten material rises

from the mantle and

erupts; pushing older rock to both sides

This process is known as

sea-floor spreading!

What is the evidence for Sea-floor spreading?Evidence from

Molten MaterialEvidence from

Magnetic Strips Evidence from

Drilling Samples

How can the ocean floor keep from getting wider and wider?

The older ocean floor plunges into deep-ocean

trenches in a process

known as subduction Sea-floor spreading

and subduction work

together like a giant conveyer belt!

Section 5: What is the theory of plate tectonics?

The Earth’s lithosphere is

cracked into separate

sections known as plates Geological theory states that

these plates are in

constant, slow motion,

driven by the convection

currents in the mantle

How is the theory of plate tectonics different from continental drift?

Continental drift is based on the movement of

the continents DUE to plate tectonics Continents are NOT the same as plates Tectonic plates can be made up of both

oceanic crust and continental crust

What happens where the plates meet?

Plate Boundaries –

where the edges of the

lithosphere meet; faults form along these boundaries:

TransformDivergentConvergent

What are Transform boundaries?

The place where two

plates slip past each other, moving in

opposite directions

Earthquakes occur frequently at these

boundaries

What are Divergent Boundaries?

The place where two

plates move apart, or diverge and create a

rift valley

Most occur at the mid-ocean ridge although

some can occur on land

What are Convergent boundaries?

The place where two plates come

together, or converge creating a collision

Subduction occurs at convergent boundaries

The density of the crust

determines which crust will be on top

– if both plates are the same density

they form a mountain range