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Earth’s Sub-Surface Processes. CONTINENTAL DRIFT. The process by which the continents move slowly across Earth’s surface. PLATE TECTONICS. The theory that pieces of the Earth’s lithosphere, called plates, move about slowly on top of the asthenosphere. ALFRED WEGENER.

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continental drift
CONTINENTAL DRIFT

The process by which the continents move slowly across Earth’s surface.

plate tectonics
PLATE TECTONICS

The theory that pieces of the Earth’s lithosphere, called plates, move about slowly on top of the asthenosphere.

alfred wegener
ALFRED WEGENER
  • German scientist who first introduced the theory Kontinentalverschiebung...

AKA CONTINETAL DRIFT

  • Recognized that South America and Africa fit together like a puzzle
slide6
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
slide7
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
slide8
The evidence Wegener needed…

Seafloor Spreading:

The movement of the ocean floor away from either side of a mid-ocean ridge

Creates NEW CRUST!!!

slide9
Mid-Ocean Ridges:

A system of undersea mountain ranges that wind around the earth

slide10
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 less

dense material

Zone of Subduction

slide11
Oceanic-oceanic crust

Oceanic-continental crust

Forms:

Volcanic Island Arcs & Deep trenches

understanding the t heory of plate tectonics
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.
slide13
Lithosphere

Crust

Mantle

Outer Core

Inner Core

slide14
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)

slide15
PLATE BOUNDARIES

Transform Fault

Divergent

Convergent

slide16
Convergence

Divergence

slide18
Transform Fault:

San Andreas Fault

slide21
Stress: Folding & Faults

Compression

Tension

Shearing

slide22
Tension

Rocks are pulled apart

Occurs at divergent boundaries

Rocks become thinner

slide23
Compression

Crustal rocks are pressed together

Occurs at convergent boundaries

Pushes rock higher up or deeper down in the crust

slide24
Shearing

This stress pushes rocks in opposite direction

Sheared rock bends, breaks, and twists as they slide past each other

Occurs at transform faults

slide25
Result of Stress

Folding

ANTICLINE: up-curved folds in layers of rock

SYNCLINE: down-curved folds in layers of rock

MONOCLINE: gently dipping bends in horizontal rock layers

slide29
Result of Stress

Faul ting

If there is no movement on either side of break…this is a fracture.

When there is movement, this is a fault

slide31
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)

slide33
http://youtu.be/ryrXAGY1dmE

Hawaii Hotspot

Seafloor spreading and Megathrust

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