Earth’s Sub-Surface Processes
CONTINENTAL DRIFT
The process by
which the
continents move
slowly across Earth’s
surface.
PLATE TECTONICSThe theory that pieces of the
Earth’s lithosphere, called
plates, move about slowly on
top of the asthenosphere.
ALFRED WEGENERGerman scientist who first
introduced the theory Kontinentalverschiebung...
AKA CONTINETAL DRIFT
Recognized that South America and Africa fit together like a puzzle
PANGEA
What’s the evidence????•Similarities of coastlines of continents (fit
together like a puzzle)•Discoveries and correlations of worldwide
distribution of plant and animal fossils•Records of Earth’s ancient magnetism
captured in lava flows
What’s the evidence????•Observations of the flow of heat from Earth’s
interior•Studies of the nature and exploration of the
ocean floor•Locations of volcanoes and records of
earthquakes
The evidence Wegener needed…Seafloor Spreading:
The movement of the ocean floor away from either side of a mid-ocean ridge
Creates NEW CRUST!!!
Mid-Ocean Ridges:A system of undersea mountain ranges that wind around the earth
Subduction:When one plate moves under another plate at a
plate boundary.
Why does this happen?? Oceanic crust is more dense than continental crust, so
it is forced under the lessdense material
Zone of Subduction
Oceanic-oceanic crustOceanic-continental crust
Forms: Volcanic Island Arcs & Deep trenches
Understanding the Theory of Plate Tectonics•The theory not only describes continental movement,
but also proposes an explanation of WHY and HOW continents move.•Tectonics is the study of the formation of features in the
Earth’s crust.•The theory that pieces of the Earth’s lithosphere, called
plates, move about slowly on top of the asthenosphere.
CrustLithosphere
Mantle
Outer Core
Inner Core
CRUST: outer surface; can be oceanic or continental
LITHOSPHERE: rigid interior of crust
ASTHENOSPHERE: plastic upper mantle
MANTLE: molten rock
OUTER CORE: liquid iron nickel
INNER CORE: solid iron nickel
Solid rock that slowly flows(Like putty)
PLATE BOUNDARIESDivergent Convergent Transform Fault
Pull away from each other Crash into each other Slide past each other
Divergence
Convergence
Convergence
Transform Fault:
San Andreas Fault
National Geographic video
Stress: Folding & Faults
Compression
Tension
Shearing
TensionRocks are pulled apart
Occurs at divergent boundaries
Rocks become thinner
CompressionCrustal rocks are pressed together
Occurs at convergent boundaries
Pushes rock higher up or deeper down in the crust
ShearingThis stress pushes rocks in opposite direction
Sheared rock bends, breaks, and twists as they slide past each other
Occurs at transform faults
Result of StressANTICLINE: up-curved folds in layers of rock
SYNCLINE: down-curved folds in layers of rock
MONOCLINE: gently dipping bends in horizontal rock layers
Anticline
Syncline
Monocline
Result of Stress
If there is no movement on either side of break…this is a fracture.
When there is movement, this is a fault
Normal fault Occur along divergent boundaries and the hanging wall moves downward, relative to the footwall
Reverse fault Occurs along convergent boundaries and the hanging wall moves upward, relative to the footwall
Strike-slip fault Occurs along transform fault boundaries and the rock on either side of fault slides horizontally
Thrust fault special reverse fault where fault plane is nearly horizontal (common in steep mountains)
This Type of PLATE BOUNDARY
Place where two plates meet
Creates this type of STRESS
Force acting on a rock to change its shape or volume.
That Stress, creates this type of FAULT
Break in the crust, where rocks slip past each other
CONVERGENT BOUNDARY
Two Plates Move Towards Each Other
COMPRESSION STRESS Rock is Squeezed Together
REVERSE FAULT
Hanging Wall forced UP the Footwall
DIVERGENT BOUNDARY Two Plates Move Away From Each Other
TENSION STRESS Rock is Stretched Out
NORMAL FAULT
Hanging Wall Slides DOWN the Footwall
TRANSFORM BOUNDARY Two Plates Move Parallel To Each Other
SHEARING STRESS Rock is Pushed in Two Opposite Directions
STRIKE ‘N’ SLIP FAULT
Hanging Wall Moves PARALLEL (Left or Right) to the Footwall.
http://youtu.be/ryrXAGY1dmE
Hawaii Hotspot
Seafloor spreading and Megathrust