earth science layers of the earth. the earth’s layers layers
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Earth Science
Layers of the Earth
The The Earth’sEarth’s LayersLayers
Lithosphere
• The top part of the layer is the Earth’s crust.
• The outermost layer of the earth known as the “rock sphere” that we live on.
• It is divided into pieces called tectonic plates
Asthenosphere
• The soft layer of the mantle below the lithoshphere.
• Tectonic plates move above this layer.
Outer Core
• The liquid layer below the earth’s mantle.
• This layer surrounds the inner core.
Inner Core
• The solid, dense center of our planet.
• It is about 6,374 km. beneath the earth’s surface.
“Plate tectonics” Theory:
explains motion/behavior of Earth’s lithosphere
Moves a few centimeters a year
explains volcanoes, mountain building and earthquakes
stiff lithosphere floats on top of weak asthenosphere
Plate tectonics about a dozen or so plates
Modernmeasurements
Supporting evidenceSupporting evidenceSupporting evidenceSupporting evidence
What drives the plate movement?
EARTH is a Heat EngineEARTH is a Heat Engine
Tectonic Plates
• The place where two tectonic plates meet is called a plate boundary.
Plate BoundariesPlate Boundaries
divergent boundaries
convergent boundaries
transform fault boundaries
3 types
• http://www.wwnorton.com/college/geo/earth2/content/chapter_4/animations.asp
2) Plate boundaries2) Plate boundariesPLATEPLATETECTONICSTECTONICS
Divergent boundaries
Mostly mid-ocean ridges (seafloor spreading)
Typical spreading rates ~ 5 cm/year
As oceanic moves away from ridge, it cools, & becomes denser
Also found where continents break apart
Example: Red Sea and East African Rift
Mid Ocean Ridges
http://earthquake.usgs.gov/learning/animations/
Continents Break Apart – Rift Valley
2) Plate boundaries2) Plate boundariesPLATEPLATETECTONICSTECTONICS
Divergent boundaries
Also found where continents break apartExample: Red Sea
http://www.wwnorton.com/college/geo/animations/sea_floor_spreading.htm
Red Sea (looking southeast)
2) Plate boundaries2) Plate boundariesPLATEPLATETECTONICSTECTONICS
2) Plate boundaries2) Plate boundariesPLATEPLATETECTONICSTECTONICS
Divergent boundariesContinents breaking apart Example: East African Rift
Red triangles show the active volcanoes and the Afar Triangle (shaded, center)
Divergent Plate BoundariesDivergent Plate Boundaries
2) Plate boundaries2) Plate boundariesPLATEPLATETECTONICSTECTONICS
Convergent boundaries
Subduction zones
ocean-continent
ocean-ocean
continent-continent
- VolcanoesExamples: Mount St. Helens
- Volcanic island arcs Examples: Marianas, Aleutians, Hawaii
- Mountain BuildingExamples: Himalayas, Alps, Appalachians
ConvergentConvergent Plate boundariesPlate boundaries
continental crust and continental crust
• Mountain building
Oceanic and oceanic crust• DEEPEST Trenches and Island Arcs
Oceanic crustOceanic crust
Continental Crust and Oceanic Crust• Trenches and explosive volcanoes
Molten rock
Oceanic crust Continental crust
volcano
SUBDUCTION ZONE
• Mountains
• Volcanoes, trenches & earthquakes
Transform fault boundaries
Strike-slip faulting
Plates slide past each other: no production/destructionof material
2) Plate boundaries2) Plate boundariesPLATEPLATETECTONICSTECTONICS
STRESS• Stress occurs at plate boundaries. Stress
causes rock to change shape or deform (deformation)
Types of Stress: Type of boundary
– Compression
– Tension
– Shearing
convergent
divergent
transform
Stress Causes Deformation
Deformation Bends and Breaks Rock
If you bump your bike into a large rock two things can happen.
The metal can either bend or snap.
Stress Cause - CompressionEffect: Folding
• Folding- When rock layers bend because of stress on the earth’s crust.
The types of folding are:
Folding
• Anticline- Arch shape folds in the earths’ crust.
• Syncline- Trough shaped fold in a rock.
pushing
pushing
Monocline
• Monocline – simplest - involves a slight bend on one side
Anticline
Anticline
Anticline
Folding
• Syncline- Trough shaped fold in a rock.
Syncline
Syncline
Syncline
Syncline
Syncline
Monocline
• Monocline – simplest - involves a slight bend on one side
Monocline
Monocline
Monocline
Monocline
Monocline
Tectonic Plates
• The place where two tectonic plates meet is called a plate boundary. (When there is enough pressure that builds up on the rocks’ edges and earthquakes can occur).
• Earthquake Facts
Earthquake Animation
Tectonic Forces• Faulting- Stress that causes rocks to
break
• Faults slide past each other.
• The types of faulting are:
- normal fault
- reverse fault
- strike-slip fault
Fault Type #1: Normal Fault Cause: Tension/ Divergent movement
Normal Faults- Effect: The hanging wall moves down, relative
to the footwall. Normal because of the
pull of gravity.
Normal Fault
NormalFault
Normal Fault
Fault Type #2: Reverse Fault
Cause: Compression/ Convergent MovementReverse Fault-
Effect: The hanging wall moves up relative to the
footwall.
Reverse Fault
Reverse Fault
Reverse Fault
Reverse Fault
Strike-Slip FaultCause: shearing/ crosswise movement
Strike-slip Faults-
Effect: When opposing forces cause rock to
break and move horizontally.
Strike Slip FaultStrike Slip Fault
Strike Slip FaultStrike Slip Fault
Strike Slip FaultSan Andreas Fault
Mountain BuildingCause: CompressionEffect: Uplift – crust is raised to higher
elevation
• US Geological Survey scientist Chris Newhall attaches a tape measure to a cliff on Bubuin Island. Activity from nearby Volcano Island has lifted Bubuin by 15 centimeters
Grand Canyon
Folded Mountains• In a folded mountain range, the rock layers are
folded up.
Folded Mountains
• Fault-Block
• Folded
• Volcanic
Folded Mountains
Sierra Nevada
Folded Mountains
Appalachian
Folded MountainsAppalachian Mountains
Fault-BlockMountains
• Fault-Block
Fault- Block Mountians
• Rock layers are tilted up and can have sharp jagged peaks.
Fault-Block MountainsGrand Tetons from Jackson Lake Lodge (WY)
are examples of fault block mountains.
Fault Block Mountain
Fault-Block Mountains
• Big Bend Texas
Volcanic Mountains
• Volcanic mountains are often cone shaped, and form along convergent boundaries.
• Also forms along the divergent sea floor spreading
Volcanic Mountains
Volcanic Mountains• Mt. Ranier, Washington
Volcanic MountainsMt. St. Helens, Washington
Volcanic Mountains
Mt. Shasta, California
Volcanic Mountains• Volcanic mountains of Guatemala make up
part of the Pacific's "Ring of Fire".
Popocatepetl, Mexico. December 12, 2007 this volcano spewed lava and ash two miles high.
Volcanic Mountains• Mt. St. Helens- Live
• On May 18, 1980, Mount St. Helens violently erupted. For 2 months the volcano showed signs that it was waking up from its 123-year sleep.
• Earthquakes beneath the mountain increased. Steam and ash erupted.
• And a "bulge" grew on the mountain's steep north side. All these warning signs signaled that magma was moving upward inside the volcano.
US Volcanoes
• Cascade Range Volcanoes
• Major West Coast Volcanoes
• Hawaii Volcano Map