Transcript Geology Notes - My Teacher Pages

The Solid Earth
Earth’s Structure
• Core
• Mantle
• Crust
Earth’s Structure
Earth’s Structure
Core
• Innermost portion of the earth
• Inner core is VERY hot, but solid
• Outer core is liquid molten material
Mantle
• Surrounds the core
• Most is solid rock, but under the outermost
part is a zone of hot, partly melted rock
that flows like soft plastic called the
asthenosphere
Crust
• Outermost and thinnest layer
• Continental crust-under continents
• Oceanic crust-under the oceans (71% of
the crust)
Internal Earth Processes
• 2 kinds of movement of the earth
– Convection cells: large volumes of heated
rock that move following a pattern similar to
the atmosphere (warmer is less dense)
– Mantle plumes: mantle rock flows slowly
upward, reaching the surface and spreading
out (oceanic ridge)
Convection Currents
Mantle Plume
Plate Tectonics
• Tectonic plates (~60miles thick) consist of
continental and oceanic crust and rigid
outermost part of the mantle-called the
lithosphere
• Plates move constantly supported by the
flowing asthenosphere
• Produces mountains, oceanic ridges,
trenches, etc.
Plate Movment
Plate Tectonics
3 Types of Plate Boundaries
• Divergent plate boundary: plates move
apart from each other
• Convergent plate boundary: plates moving
toward each other (earthquakes)
• Transform Fault: plates slide past each
other
Divergent Plate Boundary
Convergent Plate Boundary
Transform Fault
• http://www.youtube.com/watch?v=QDqsklt
CixA
External Earth Processes
• Geologic changes based directly or
indirectly on energy from the sun and
gravity
– Erosion
– Weathering
Erosion
Erosion
• Material is dissolved, loosened, or worn
away from one part of the earth’s surface
and deposited in other places
– Streams
– Wind
– Human activities that accelerate erosion (acid
rain)
Weathering
• Produces loosened materials that can be
eroded
• Two types
– Mechanical (frost)
– chemical
Minerals
• An element or inorganic compound that
occurs naturally (solid)
– Can be an element (gold)
– Can be a combination of elements (salt,
quartz)
Rocks
• Material that makes up a large, natural
continuous part of the crust
– Most consist of 2 or more minerals
Three main Rock Types
• Igneous
• Sedimentary
• Metamorphic
Igneous
• Formed when magma (molten lava) wells
up, cools, and hardens; most of the earth’s
crust
– Granite
– Lava
Igneous
Sedimentary
• Formed from sediment that is weathered
into smaller pieces, transported, and
deposited into a body of water, pressed
together, forming layers
– Sandstone
– limestone
Sedimentary
Metamorphic
• Formed when preexisting rock partially
melts, or is subjected to high pressure
– Slate
– marble
Metamorphic
Rock Cycle
Natural Hazards-Earthquakes
• Stress in the earth’s crust cause a fracture
in solid rock, producing a fault
• Energy is released as shock waves
moving outward from the focus
– Focus: point of initial movement
– Epicenter: point on the surface directly above
the focus
Earthquakes
Earthquakes
• Magnitude measured by the Richter Scale
• Seismograph measures amplitude of vibrations
(each unit represents an amplitude that is 10X
greater than the one before it) ex. An earthquake
of 6.0 is 100x greater than a 4.0
–
–
–
–
–
–
Insignificant
Minor
Damaging
Destructive
Major
Great
<4.0
4.0-4.9
5.0-5.9
6.0-6.9
7.0-7.9
>8.0
Seismogram
Earthquakes
• Aftershocks can last up to 4 months
• Foreshocks can occur seconds to weeks before
main shock
• Primary Effects: shaking, permanent ground
displacement, damage to infrastructure
• Secondary Effects: rock slides, urban fires,
flooding, tsunamis
• http://www.youtube.com/watch?v=g15sZ_d2WU
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Natural Hazards-Volcanoes
• Magma reaching the earth’s surface
• Can release:
– Ejecta (rocks, debris)
– Liquid lava
– Gases (water vapor, carbon dioxide, sulfur dioxide)
• Concentrated where there is seismic activity
• Gases can remain in the atmosphere for up to 3 years,
causing a cooling effect by as much as 1oF
• http://www.youtube.com/watch?v=bgRnVhbfIKQ
• http://www.youtube.com/watch?v=Hec9yKQQ4o
Volcanoes
Earthquake/Volcanic Activity