Transcript Geology Power Hour Powerpoint Geology Power Hour

Learning Objectives
1. I can list and identify the 3 types of
rocks and explain how they are
created.
2. I can describe how the surface of the
Earth is shaped by building up,
weathering and erosion.
3. I can identify the 3 layers of the Earth
and their features.
Learning Objectives
4. I can explain how and why plates move, the
effects of their movement, and the difference
between convergent, divergent, and transform
plate boundaries.
5. I can list and describe the three types of
volcanoes.
6. I can use evidence such as layers of fossils
and sediments, current landforms, and tectonic
movements as evidence of geologic processes
that have changed the Earth’s surface.
The
Rock
Cycle
Images from Geology.com unless otherwise
noted
What are Rocks?
• A rock is a naturally
occurring solid mixture of
one or more minerals, or
organic matter
• Rocks change over time
through the rock cycle
Rock Types
• Rocks can be classified into groups just like
living organisms.
• Rocks are classified by how they are formed,
their composition, and texture
• The three main groups are:
IGNEOUS
SEDIMENTARY
METAMORPHIC
The Rock Cycle
melting
Another look at the Rock Cycle
Igneous Rocks
• Igneous rocks form when magma or lava
cools and becomes solid
• Magma is a mixture of
many minerals
http://www.fi.edu/fellows/payton/rocks/create/igneous.htm
Magma and Lava
• Magma is melted rock
inside of the Earth
• Lava is magma that
reaches the surface.
http://www.fi.edu/fellows/payton/rocks/create/igneous.htm
Igneous Rocks
 Intrusive Igneous Rocks:
Rocks that are made from
magma (inside the earth)
 Extrusive Igneous Rocks:
forms when magma erupts
onto the Earth’s surface
(lava), cools quickly with very
small or no crystals formed
http://www.windows.ucar.edu/tour/link=/earth/geology/ig_intrusive.html&edu=high&fr=t
Intrusive Igneous Rocks
 Phanertic crystals – large
crystals formed in
intrusive igneous rocks
 Crystals form because the
rocks cool slowly enabling the
large crystals to grow
http://www.windows.ucar.edu/tour/link=/earth/geology/ig_intrusive.html&edu=high&fr=t
Igneous Rocks
Coarse-Grained
Fine-Grained
Felsic
Granite
Rhyolite
Mafic
Gabbro
Basalt
Metamorphic Rocks
• Metamorphic rocksHeat and Pressure form
Metamorphic Rock
• Occurs deep within the
Earth (not on the
surface)
Metamorphic Rocks
• Igneous and sedimentary rocks
can form into metamorphic rocks
when under a lot of heat and
pressure within the earth
Sediments

Sediments are pieces of rock, minerals, and
organic remains.

Sediments are formed by weathering.

Due to erosion sediments are moved from
one place to another

Sediments are deposited in
layers, with the older ones
on the bottom
http://www.fi.edu/fellows/payton/rocks/create/sediment.htm
Sedimentary Rocks
•
Sedimentary rock is formed
when layers of sediments
become compacted
and cemented together
Geodes
• Geodes are created in the hollow areas of
soil such as animal burrows or tree roots.
They are also formed in the bubbles in
volcanic rock.
• Water filters through the rock bringing in
minerals which harden into an outer shell
creating the geode
Weathering
Weathering is the breaking down
of rocks and other materials on
the earth’s surface
Two Types of Weathering
Mechanical Weathering
Chemical Weathering
Mechanical Weathering
• No change in the rock’s chemical
composition only physical.
• Examples:
– Temperature
– Ice Wedging
– Abrasion
– Wind
– Root Pry
Chemical Weathering
• Changes the chemical composition of the
rock
• Examples:
– Acid
– Oxidation (causes rust)
– Plant Acid
Erosion
• Erosion- The process by which weathered
rock and soil particles are moved from
place to place
–
–
–
–
–
Gravity
Glaciers
Wind
Surface Water / Running Water
Ocean Shoreline / Ocean Waves
The Layers of the Earth
© Copyright 2006. M. J. Krech. All rights reserved.
The Three Main
Layers
• The three main
layers are:
– Crust
– Mantle
– Core
• Outer Core
• Inner Core
The Four Layers
• Crust - the thin
layer you live on
• Mantle - the ability
to flow like liquid.
• Outer core made of liquid iron
and nickel
• Inner core - solid
because of
temperatures and
pressure are great
Pangaea
An ancient supercontinent that scientists
believe existed from about 200 to 300 million
years ago.
How is this possible?!?!?
Geological Changes—3:25
Continental Drift
• Alfred Wegener was the 1st scientist to
come up with the idea of “continental
drift”
• His idea was that the continents slowly
moved away from each other.
• This supercontinent was called Pangaea.
Continental Drift Evidence
o Minerals, fossils, and mountains, on now
different continents, match if the continents
were together
The Mystery of Brachiosaurus (~3 min)
Plate Tectonics Theory
 The lithosphere is divided into
a number of large and small
plates and the plates are
floating on the mantle.
Lithosphere = the Earth’s crust plus
the upper portion of the mantle layer
Plate Boundaries
Plate Boundaries
Divergent boundary:
o Plates are moving away from each
other
o Mid-ocean ridges are created and
new ocean floor plates are created
called Seafloor Spreading
Seafloor Spreading Theory:
•
•
Ocean floors are moving like broad
conveyor belts
Forms new crust through the upwelling of
magma
Plate Boundaries
Divergent boundary:
 Convergent Boundary:
plates are moving toward
each other and are colliding
(3 types)
Convergent Boundaries Create:

Subduction zone-Places where
plates are moving toward each other
and one plate melts under the other
and the magma moves upward to
form volcanoes.
1. When Ocean Plates collide with
Continental Plates
• Create subduction
zones,
• Trenches
• Create near coast
volcanoes
– Example: Cascade
Mountains
2. When Ocean plates collide with
other Ocean plates
– Island arcs are created
(a pattern of volcanic islands created from
a subduction zone that is located off the
coast)
Example: Japan and Philippines
3. When a Continental plate collides
with another Continental plate
• Mountain ranges are
created
– (example: Himalayan
Mountains)
What About Hawaii?
• Do you see any plate boundaries
there?
Hawaii
What About Hawaii?
• Hawaiian Volcanoes
form from HOT
SPOTS
Hot spots are places
where the mantle is
unusually hotter than
other parts of the
mantle or an unusually
weak (thin) part of
the crust…(we’re not
sure why)
Hot Spots

Magma that may originate in the
mantle or outer core will move
upward, breaking the surface and
forming a volcano, they are
independent of plate boundaries and
a chain of volcanoes may form as the
plate moves across a hot spot.
Hot Spots

(Examples: Hawaiian Islands and
Yellowstone National Park)
Transform Fault Boundary
 Plates are neither moving
toward nor away from each
other, they are moving past
one another.
Transform Fault Boundary
 The plates may move in opposite
directions or in the same
directions but at different rates
and frequent earthquakes are
created (example: San Andreas
Fault)
San Andreas Fault
Why is Earth not getting bigger or
smaller?
NOTE:
o Plates are destroyed as fast as they
are created (2 ways)
o Plates may be subducted and melted
or may push be pushed upward to
form mountains
Convection Currents
Convection currents occur within the mantle

The up-welling leg of the current creates a
divergent boundary which produces
midocean ridges
Convection Currents

Seafloor Spreading
The down-welling leg of the current
creates one type of convergent boundary
that results in trenches and a subduction
zone
Introduction to volcanoes
Volcano:
an opening in the earth’s surface
through which lava, hot gases, and
rock fragments erupt
Origin of Volcanoes
 A crater is formed when the
volcano sides are higher than the
vent forming a depression
Types of Volcanoes
•
•
•
•
Shield
Composite (Strato-)
Cinder
(Super volcanoes)
Types of Volcano Mountains
Shield Volcanoes:

Large base, gentle slope, lava rock
layers

A few miles high

Life span of a million years or more

The lava is hot, low viscosity
(thinner, more watery), often
basaltic.

Usually gentle, slow eruptions

Example: Hawaiian Islands
Shield volcanoes
• Mauna Loa
see it’s low, broad shape
Cinder cones, the burps of the
volcanic family
• Relatively small in size, hundreds to 2,000
feet tall
• Usually steep sided and cone shaped.
• Found on the outskirts of all types of
stratovolcanoes and shield volcanoes
Composite Volcanoes
aka Strato-Volcanoes
• Typically large, steep sided, up to 8,000 ft
above their bases.
• Have a crater at the summit which contains a
central vent or a clustered group of vents.
Composite volcanoes
• Found near “subduction zones.”
– Denser oceanic plates sliding beneath
continental plates
– Oceanic crust melts, rises through continental
crust, creates chain of volcanoes
Composite Volcano Eruptions
• Very violent, explosive and
BIG!!!
• Entire sides of mountain
gone in a few seconds.
Historically cool… Mt. Vesuvius
A whole dead city, entombed in
ash!
Now onto supervolcanoes
• Hold on to your hats, it’s the end
of the world!
What are super volcanoes?
• Super volcanoes are those that have
extremely high levels of silica
• This makes for crazy viscous (thick &
“sticky”) lava, and HUGE eruptions
• The lava is so viscous it doesn’t even
allow for a cone shaped volcano
Yellowstone
• Created by a hot spot
• Evidence from the Snake River Valley of
past eruptions and calderas
• So explosive it clears away enough crust
that low viscosity basalt can sometimes
come up
• Can change the course of geologic history
What are the consequences of it
blowing?
• We could hear it blow in Washington
• Ash goes into the layer of atmosphere
called the stratosphere, which will remain
and block sunlight
• The entire Earth would cool, potentially
causing an ice age
• If no ice age, definitely crops would die
and food shortages would occur
• People are gonna die!