types of plate boundaries 1. convergent 2. divergent 3. transform
DESCRIPTION
Plate tectonics. TYPES OF PLATE BOUNDARIES 1. Convergent 2. Divergent 3. Transform. TYPES OF PLATE BOUNDARIES. 1. Convergent 2. Divergent 3. Transform. PLATE BOUNDARIES. Divergent Plates move apart and new crust is formed Heat from below rises - PowerPoint PPT PresentationTRANSCRIPT
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 boundariesDivergent
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