Transcript Describing Matter & Energy

Plate Tectonics
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According to the theory of plate tectonics, the
movement of Earth’s plates produces volcanoes,
mountain ranges, earthquakes, and features of the
ocean floor.
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What are Earth’s plates and what are they made of?
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What was Wegener’s hypothesis about Pangaea?
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Earth’s plates are large pieces of the lithosphere made up of solid
rock. They include oceanic and continental crust.
The continents collided and formed a great landmass called
Pangaea millions of years ago
What do scientists think is the cause of plate motion?
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Movement of material in the upper mantle, which drags the
overlying plates along.
Plate Tectonics
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Describe how new features of Earth’s surface result
from the movement of Earth’s plates.
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When plates collide, trenches, volcanoes or mountain
ranges form. When plates pull apart, mid-ocean ridges, rift
valleys or new oceans form.
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Continental Drift, Pangaea and Plate Tectonics.
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Exploring Plate Tectonics
Earth’s Crust in Motion
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Stress in the crust
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Types of Stress
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Shearing
Tension
Compression
How does deformation change Earth’s surface?
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Earthquakes
Stress
It causes it to bend, stretch, break, tilt, fold and slide
Which type of deformation tends to shorten part of
the crust?
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Compression is the type of deformation that may shorten
part of the crust by pushing it together
Earth’s Crust in Motion
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Kinds of faults
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Strike-Slip Fault
Normal Fault
Reverse Fault
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Which half of the reverse fault in the picture on pg. 361 slid up and
across…the hanging wall or the footwall? Explain.
The hanging wall slipped up and across. If the footwall had moved
up, the fault would be called a normal fault.
What force of deformation produces each fault?
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Strike-slip – shearing, normal – tension, reverse –
compression
Earth’s Crust in Motion
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Friction along Faults
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What is friction and why does it exist?
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Friction is the force that opposes the motion of one surface as it
moves across another surface. Friction exists because surfaces are
not perfectly smooth.
Relate friction to the strength of earthquakes.
Mountain Building and Uplift
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Describe how mountains are formed by faulting
Describe how mountains are formed by folding
What kind of formations do anticlines and synclines form?
Other than mountains, what else is formed by uplift?
Earth’s Crust in Motion
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Fault Lines, Stress, and Earthquakes
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What are the 3 main types of stress in rock?
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Describe the movements that occur along each of the
3 types of faults.
How does Earth’s surface change as a result of
movement along faults?
Earth’s Crust in Motion
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What are the 3 main types of stress in rock?
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Describe the movements that occur along each of the
3 types of faults.
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Shearing, tension and compression
Strike-slip fault: the rocks on either side of the fault slip
sideways past each other with little up-or-down motion.
Normal fault: the hanging wall slips downward past the
footwall. Reverse fault: the hanging wall slides up and over
the footwall.
How does Earth’s surface change as a result of
movement along faults?
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Movement along faults can create mountains and valleys.
Measuring Earthquakes
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Where does an earthquake begin? How does the
energy reach the surface?
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Relate seismic waves and the focus. Where is the
energy the greatest?
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Earthquakes always begin in the lithosphere within 100 km
of Earth’s surface. The seismic waves carry the energy.
Seismic waves carry the energy of an earthquake away from
the focus, through Earth’s interior and across the surface.
The energy of the seismic waves that reach the surface is
greatest at the epicenter.
Describe the 3 categories of seismic waves and how
they relate to one another.
Measuring Earthquakes
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How do geologists detect seismic waves?
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Describe the 3 ways of measuring earthquakes.
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The Mercalli Scale
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How would you rate the damage to the Folignocity hall (pg. 371) on
the Mercalli scale?
The Richter Scale
The Moment Magnitude Scale
How do geologists locate the epicenter?
Distinguishing between faults:
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Normal Fault
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Reverse Fault
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Your hanging wall drops below your footwall
Your hanging wall moves up above your footwall
Your footwall looks like a foot.
When it states “the hanging wall is above the
fault”, they mean, regardless of the type of
fault, your hanging wall sits on your footwall
Hanging
wall
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Foot
wall
Let’s take a look using 2 binders
Volcanic Activity
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Let’s explore a volcano
An eruption occurs when gases trapped in magma
rush through an opening at the Earth’s surface,
carrying magma with them
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Where does the magma come from? What causes it to rise?
How does heat affect the flow of magma?
Describe magma high in silica. Is the lava thick or thin?
What types of rocks does it produce?
Describe magma low in silica. Is the lava thick or thin?
What types of rocks does it produce?
Volcanic Activity
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Volcanoes can erupt quietly or explosively, depending
on the silica content of the magma
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What causes a quiet eruption versus an explosive one?
What types of lava are produced by quiet eruptions?
What is produced by an explosive eruption? See pg 379 for
a picture.
How would you relate hot springs and geysers to
volcanic activity?
Volcano hazards include pyroclastic flows, avalanches
of mud, damage from ash, lava flows, flooding and
deadly gases.
Volcanic Activity
The phases of a volcano
Volcanic Landforms
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Landforms formed by magma:
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Magma that hardens beneath the surface forms batholiths,
dome mountains, dikes and sills, which are eventually
exposed by erosion
This would be caused by magma that rises through the
cracks in the upper crust, but fails to reach the surface
Landforms formed by lava and ash:
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Lava and other volcanic materials on the surface create
shield volcanoes, cinder cones, composite volcanoes and
plateaus
Calderas are formed when a volcano has emptied it’s magma
chamber. See pg. 390 for an example
Volcanic Landforms
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What features form as a result of magma hardening
beneath Earth’s surface?
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Describe how a dome mountain can eventually form out of
magma that hardened beneath Earth’s surface
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Magma forces its way upward through cracks in the crust, but
overlying rock layers keep the magma from reaching the surface.
The magma forces the rock layers to bend upward into a dome
shape. When the rock layers wear away, the dome is exposed.
Describe 5 landforms formed from lava and ash.
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Volcanic necks, dikes, sills, batholiths, dome mountains
Shield volcanoes, cinder cone volcanoes, composite volcanoes, lava
plateaus and calderas
Describe the process that creates a lava plateau
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Thin, runny lava flows out of several long, horizontal cracks and
travels far in all directions before cooling and hardening. Over time,
layers of lava build up, forming a plateau.