TYPES OF PLATE BOUNDARIES

1. Convergent

2. Divergent

3. Transform

Plate tectonics

TYPES OF PLATE BOUNDARIES

1. Convergent 2. Divergent3. Transform

DivergentPlates move apart and

new crust is formed Heat from below rises

Under ridges, underlying rock melts, comes to surface and creates new crust

Mid-ocean ridges are long chains of volcanoes

Locations of shallow earthquakes

PLATE BOUNDARIES

Divergent

Sea-floor spreading(i.e. Atlantic ocean) atMid-Ocean Ridges

PLATE BOUNDARIES

Divergent

On Continents: Continental rifting (i.e. African and Arabian plates to form Red Sea)

Animation 1. sea floor spreading

PLATE BOUNDARIES

Divergent

On Continents: Continental rifting (i.e. African and Arabian plates to form Red Sea)

PLATE BOUNDARIES

Divergent

On Continents: Continental rifting (i.e. African and Arabian plates to form Red Sea)

PLATE BOUNDARIES

Divergent

Age of Ocean floor increases away from divergent boundary

PLATE BOUNDARIES

Transform

Plates move past each other (i.e. San Andreas fault)

Ocean floor transform faults

Evidence shallow earthquakesno volcanoesGeodetic rates across faults

PLATE BOUNDARIES

PLATE BOUNDARIES

TransformPlates move past each

other (i.e. San Andreas fault)

-shallow earthquakes

-no volcanoes

PLATE BOUNDARIES

Convergent

Plates move toward each other

-shallow, intermediate and deep earthquakes

For example off the coast of Washington

PLATE BOUNDARIES

Convergent

a. Ocean & Continent (Juan de Fuca & N America)

Ocean crust more dense compared to continental crust dives under continents

Deep trenches created where the plates dive under continents

Large earthquakesVolcanoes over the

subducting slab on the overriding plate

PLATE BOUNDARIES

Pacific-North America plate boundary

1) Convergent boundary in PNW

2) Divergent boundary between Juan de Fuca & Pacific plates

3) Transform boundary in California

4) Divergent boundary between Baja California and mainland Mexico

Convergent

b. Ocean & Ocean (off the coast of the Aleutian Islands in Alaska)

-denser plate subducts -deep trench-volcanoes created on

overlying plate = island arcs

PLATE BOUNDARIES

Convergent

b. Ocean & Ocean (off the coast of the Aleutian Islands in Alaska)

-denser plate subducts -deep trench-volcanoes created on

overlying plate = island arcs

PLATE BOUNDARIES

Convergent

c. Continent & Continent—

Thick and low density so neither subducts

Collide into each other

and create mountains

Indian Plate collides into Eurasian Plate = Himalayas,

PLATE BOUNDARIES

Convergent

c. Continent & Continent—

-Both quite thick and low density so neither subducts

-They colide into each

other and create mountains

PLATE BOUNDARIES

TYPES OF PLATE BOUNDARIES

3 plate boundaries

Divergent

Transform

Convergent

continent-ocean

ocean-ocean

continent-continent

Need name, date and class.

Neat handwriting

Question of the week:

Name the three types of plate boundaries.

The interior of the Earth

The Earth’s crust

The crust is relativelylight & brittle.

Most earthquakes occur within the crust.

The interior of the Earth

Continental crust

1) Composed of mostly granitic rocks (high Si rocks)

2) These rocks are rich in quartz & feldspar

3) Continental rocks are relatively light & buoyant.

Oceanic crust

1) Composed of mostly basaltic rocks

2) These rocks are rich in feldspar & pyroxene

3) Oceanic rocks are heavier and less buoyant than crustal rocks.

The interior of the Earth

Mantle

1) Located beneath the crust

2) Dense silicate rocks

3) More iron, magnesium, and calcium than the crust

1) Hotter and denser because temperature and pressure inside the Earth increase with depth

2) Solid on and strong on short- time scales

3) Convecting on long time- scales

The interior of the Earth

Earth’s core

The Earth's core consists of two parts:

1) 2,200 km-thick liquid outer core and

2) 1,250 km-thick solid inner core.

As the Earth rotates, the liquid outer core spins, creating the Earth's magnetic field.

The interior of the Earth

SummaryCompositional layering

Core: high density, iron and nickel.

Mantle: medium density (3.3 g/cm3, iron and magnesium plus silicon and oxygen-based rocks

Crust: a) denser oceanic crust (3.0 g/cm3

b) less dense continental crust (2.7 g/cm3)Contains silicon and oxygen-based rocks

Physical layering

Defined by physical properties or rheology.

The increase in temperature and pressure with depth affects the material physical properties

The mechanical behavior of earth material may behave like:

1) brittle solid or2) deform like putty or 3) melt to become a liquid.

1. Inner Core (core) radius 1216 km solid

2. Outer Core (core) 2270 km liquid

3. Lower Mantle (mantle) 2240 km rigid layer

4. Asthenosphere (upper mantle)

660 km soft, weak layer (silly putty) top is actually slightly melted, Asthenosphere is mechanically detached from the lithosphere

Physical layering

5. Lithosphere Crust and uppermost mantle

~100 km thick, ranges from a few km up to ~400 km

Thicker under continents

Thinner under oceans, very thin at mid-ocean ridges

Rigid layer, not connected below so can move.

Physical layering