Lithospheric Plate Boundaries

Plate Tectonics Part 2

Type of Boundary

Description Special Feature Example

DIVERGENT

CONVERGENT

TRANSFORM

HOT SPOT

Type of Boundary

Description Special Feature Example

DIVERGENT 2 plates separate from each other

Move in opposite drx

Rift valley

Mid Ocean Ridge

Sea floor spreading

Mid Atlantic RidgeIcelandRed SeaGulf of Aden

CONVERGENT

TRANSFORM

HOT SPOT

Type of Boundary

Description Special Feature Example

DIVERGENT 2 plates separate from each other

Move in opposite drx

Rift valley

Mid Ocean Ridge

Sea floor spreading

Mid Atlantic RidgeIcelandRed SeaGulf of Aden

CONVERGENT 2 plates move toward each other

collide

Subduction zoneMountain chainVolcanoes/EQDeep sea trenches

Mt. St. HelensAndes Mtns.Japan/PhilippinesMarianas Trench

TRANSFORM

HOT SPOT

Type of Boundary

Description Special Feature Example

DIVERGENT 2 plates separate from each other

Move in opposite drx

Rift valley

Mid Ocean Ridge

Sea floor spreading

Mid Atlantic RidgeIcelandRed SeaGulf of Aden

CONVERGENT 2 plates move toward each other

collide

Subduction zoneMountain chainVolcanoes/EQDeep sea trenches

Mt. St. HelensAndes Mtns.Japan/PhilippinesMarianas Trench

TRANSFORM Plates slide past each other

Stressearthquakes

San Andreas Fault

HOT SPOT

Type of Boundary

Description Special Feature Example

DIVERGENT 2 plates separate from each other

Move in opposite drx

Rift valley

Mid Ocean Ridge

Sea floor spreading

Mid Atlantic RidgeIcelandRed SeaGulf of Aden

CONVERGENT 2 plates move toward each other

collide

Subduction zoneMountain chainVolcanoes/EQDeep sea trenches

Mt. St. HelensAndes Mtns.Japan/PhilippinesMarianas Trench

TRANSFORM Plates slide past each other

Stressearthquakes

San Andreas Fault

HOT SPOT Magma rises and punches through the middle of a plate

Island chains form as the plate moves ORGeysers erupt

HawaiiYellowstone NP

WHAT CAUSES TECTONIC ACTIVITY ?1. CONVECTION –

internal heat of the Earth rises

2. RADIOACTIVE DECAY – of Uranium (Ur), Thorium (Th) or Potassium (K)

3. VULCANISM4. CONDUCTIONOther planets have no tectonic

activity because they have already cooled

Movements of Plates

Make a pattern of colored stripes with markers

TYPES OF PLATE BOUNDARIES

• Divergent Margins

• Convergent Margins

• Transform Margins

• Hot Spots

DIVERGENT BOUNDARIES

• Places where 2 (or more) plates are moving apart

• Most found on ocean floor

• As plates separate, narrow “rift” valley forms

• Ex.- Mid Atlantic Ridge, Red Sea, p 249

CONVERGENT BOUNDARIES

• Place where 2 (or more) plates move toward each other, collide

• Types 1 Oceanic-Continental crusts 2 Continental-Continental Crusts 3 Oceanic- Oceanic Crust

1. Oceanic-Continental Crust

• Oceanic crust is more dense (basalt)• It is forced under the continental crust (granite)• Forms deep ocean trench, volcanic

mountains• Ex.- Peru Trench, Andes Mountains, Cascade Mtns

2. Continental-Continental Crust

• Since both plates are of equal density, neither goes under (gets subducted)

• Plates crumple

• Form uplifted mountains• Ex.- Himalayan Mtns.

3. Oceanic-Oceanic Crust

• Bigger plate forces other under• Deep ocean trenches form and volcanic

island arcs

• Ex.- Marianas Trench, Aleutian Islands

TRANSFORM BOUNDARIES

• 2 or more plates slide past each other

• Plates do not slide smoothly-earthquakes

• Scrape and move in spurts

• Ex.- San Andreas Fault

HOT SPOTS

• Small, long lasting, extremely hot area in the middle of a plate

• Provides local source of energy for volcanism

• Plate continues to move, creating new island or feature above hot spot, geysers

• Ex.- Hawaii, Emperor Sea Mounts, Yellowstone N.P.

Geysers

Illustration of Main Boundaries

Why do plate move?

• Convection Currents

Natural Hazards

• Earthquakes

• Volcanoes

• Tsunamis

Natural Resources

• Fertile Soil

• Ore Deposits

• Fossil Fuels

• Geothermal Energy