Transcript Chapter 32

Chapter 32
Standards
• Earth Science Standards
Dynamic Earth Processes : 3d, e, f
Objectives:
1. Students will define key terms for chapter 32.
2. Students will learn the layers of the Earth
3. Students will know why and how
earthquakes occur and the scales used to
measure their intense magnitude.
Key Terms
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Secondary waves
Core
Asthenosphere
Crust
Syncline
Fault
Primary waves
Key terms
• Mantle
• Lithosphere
• Anticline
Secondary waves
• A transverse body wave; cannot travel through
liquids.
Core
• The central layer in the Earth’s interior, divided
into outer liquid core and inner solid core.
Asthenosphere
• A subdivision of the upper mantle situated
below lithosphere, a zone of plastic-like, easily
deformed rock.
Crust
• The Earth’s outermost layer.
Syncline
• A fold in the strata that has relatively young
rocks at its core.
Fault
• A fracture along which visible movement can
be detected on one side relative to the other.
Primary waves (p-wave)
• A longitudinal body wave; travels through all
material and is the fastest wave.
Mantle
• The middle layer of the Earth’s interior,
between the crust and core.
Lithosphere
• The entire crust plus the portion of the mantle
above the asthenosphere.
Anticline
• A fold in strata that has relatively old rocks at
its core, with rock age decreases as you move
horizontally.
Chapter 32 Notes
What’s inside Earth?
To answer this question scientist study seismic
waves produced by earthquakes.
Three layers make up Earth’s Interior:
The crust
The mantle
The core
Each layer has its own conditions and materials.
The Crust
• Is a layer of rock that forms Earth’s outer skin.
• It includes both dry land and the ocean floor.
• The crust beneath the ocean, called oceanic
crust, consists mostly of basalt, a dark, dense
rock with a fine texture.
• The crust that forms continents, called
continental crust, consists mostly of granite
rock, larger crystals than basalt and is not as
dense.
Mantle
• Below the crust.
• A layer of hot rock.
• Crust and upper mantle form a rigid layer
called the lithosphere.
• Temperature and pressure in mantle increase
with depth.
• Pressure is the force pushing on a surface or
area.
Mantle
• The increased heat and pressure make the
part of the mantle just beneath the
lithosphere somewhat soft. This soft layer is
the asthenosphere.
• Lithosphere floats on top of the
asthenosphere.
• The rest of the mantle down to the core is
solid.
Core
• The Earth’s core consists of two parts.
• Both parts are made up of the metals iron and
nickel.
• The outer core is a layer of molten metal that
surrounds the inner core.
• The inner core is a dense ball of solid metal.
• Currents in the liquid outer core force the solid
inner core to spin at a slightly faster rate than the
spinning of the whole Earth. This movement
creates the Earth’s magnetic field.
Chapter 32.1
• All earthquakes create waves that travel
through the Earth’s interior.
• Earthquake waves = seismic waves
• A waves speed depends on the medium it
travels through.
• During an earthquake, energy is released into
the Earth’s interior and radiates in all
directions, and travels to the surface in the
form of seismic waves.
• Seismic waves reflect and refract from
surfaces.
• Geologist use seismic waves like doctors use
ultrasound to scan the insides of a body.
• Two types of seismic waves: body waves (pwaves) and surface waves (s-waves).
• Seismic waves causes the ground to shake and
move.
• The ground movement is recorded on a
seismograph.
P-wave
Rayleigh
waves
Seismic
waves
S-wave
Love waves
• Rayleigh waves move up and down in motion
• Love waves move side- to- side, whiplike
motion.
• Both surface waves
• Both move slower than p & s-waves
• Last to be registered on a seismograph
P-waves
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Move longitudinally
Compress and expand rock
Move out in all directions from their source
Fastest; reach seismograph first
Can travel through any material: solid, liquid,
etc.
S-waves
• Move transverse; up/down, side to side
• Slower, second to reach seismograph
• Can’t move through fluids; only through solids
Chapter 32.3
• Folds, faults, and Earthquakes
– The slow-moving mantle causes the lithospheric
(tectonic plates) to move slowly, but constantly.
– This movement causes stress on the plates.
Rock Folds and Expression of
Compression Force
• The slow-moving mantle causes the
lithospheric (tectonic plates) to move slowly,
but constantly.
• This movement causes stress on the plates.
Rock Folds and Expression of
Compression Force
• Compression causes rocks to buckle and fold.
• Anticline: push up folds
• Syncline: folds pushed downwards
– See diagram page 577
Faults Are Made by the Forces of
Tension or Compression
• 3 Types of Faults
– Compression = reverse fault
– Tension= normal fault
– Horizontal motion= strike-slip fault
Reverse fault
Normal Fault
Strike-slip Fault