Earth’s Sub-Surface Processes

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