Continental Drift and Plate Tectonics (notes pt. 2)

2.55 g/cm3 x 4.5 g/cm3 x 11.05 g/cm3 x 12.95 g/cm3

Plate Boundary types: Transform Boundary - Place where two plates meet and slide past each other. Also known as a sliding boundary. Example: San Andreas Fault

Plate Boundary types: Transform Boundary - Place where two plates meet and slide past each other. Transform boundaries are conservative as crust is neither created nor destroyed at them.

Plate Boundary types: Divergent Boundary – Where two plates are moving away from each other. Examples: mid-ocean ridges where new sea crust forms, rift valleys on land.

Plate Boundary types: Divergent boundaries occur along spreading centers where plates are moving apart. Two diverging oceanic plates produce sea-floor spreading and new crust formation at the boundary. They are constructive.

Diverging oceanic plates: Mid-Atlantic Ridge:

Diverging plates - (what type?) Iceland:

Plate Boundary types: Two diverging continental plates can produce surface cracking and volcanic activity. As the plates stretch, cracks appear that fill with magma, pushing the rift even wider.

Diverging continental plates: East Africa:

Rift valleys: Divergent boundaries are constructive as new crust is created at them.

Plate Tectonics (notes pt. 3)

Plate Boundary types:  Convergent boundaries occur where two plates are moving toward each other.  melting Where one plate sinks below another it is called a subduction zone.

Plate Boundary types: Oceanic crust subducting under continental crust can form continental volcanic arcs. The more dense oceanic crust melts once it descends deep enough into the mantle.

Converging Boundaries: Boundaries are destructive as crust is being lost. Ocean/Cont. Examples: Cascades, Andes volcanoes.

Plate Boundary types: Oceanic crust subducting under other oceanic crust can form volcanic island arcs. The older, more dense oceanic crust melts once it enters the mantle.

Converging Boundaries: Ocean / Ocean Examples: Aleutian Islands, Mariana Islands.

When two continental plates converge, neither is dense enough to subduct.   Since neither plate sinks, they push into one another and mountain forming happens.

Convergent Boundaries: Cont. / Cont. example: Indian plate meeting Eurasian plate

Plate irregularities: Hot spot: A volcanic area that forms as a tectonic plate moves over a point heated from deep within the Earth's mantle.

Plate irregularities : Accretion: as a continental volcanic arc forms the subducting plate has sediments and chunks scraped off that accumulate on the continental plate

Accretionary wedge Example: the west coast of North America