A Destructive Plate Margin and Constructive Plate Margin
Length: 365 words (1 double-spaced pages)
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These are the plates and were they meet
Were the arrows are pushing against each other this is called a
DESTRUCTIVE PLATE MARGIN here a oceanic plate and a lighter
continental plate push against each other the oceanic being heavier is
pushed down into the mantle and melted down then the magma finds a
crack or hole and pushes the magma above the ground to form a volcano.
Where the plates are pulling away from each other this is called a
CONSTRUCTIVE PLATE MARGIN here an oceanic and a continental plate pull
apart from each other. Magma rises to fill the gap and if it reaches
the surface it erupts as a volcano. Over time the ridge is built up by
volcanic successive eruptions and volcanic islands may appear above
the surface of the ocean e.g. surtsey.
[image - cross section of the earth]
Constructive plate boundaries
Constructive plate boundaries occur when two plates move away from
North American and Eurasian Plate
Destructive plate boundaries
Destructive plate boundaries occur when an oceanic plate is forced
under a continental plate
Pacific Plate and the Eurasian Plate
Conservative plate boundaries
Conservative plate boundaries occur when two plates slide past each
North American Plate and the Pacific Plate
Collision plate boundaries
Collision plate boundaries occur when two continental plates move
towards each other.
Indo-Australian and the Eurasian Plate
When you get plates moving apart from each other i.e. the South
American plate and the African plate. These causes a gap were magma
rises and we get a volcano. This starts in the sea but after constant
eruptions the lava builds up and solidifies. This then builds up until
the volcano gets higher and higher.
When an oceanic plate pushes against a continental plate this causes
the oceanic plate to be pushed down and be melted in the mantle then
the magma made from the melting of the oceanic plate is pushed up
through a gap to make a volcano.
1. Measuring 30 to 75 km thick the continental crust is thicker than
the oceanic crust, which is only 3 to 10 km thick.
2. The most ancient rocks, dated to more than 4 billion years, are
found in the central regions of the continents.
3. In the Pacific plate, the most ancient parts are only about 200
million years old. This crust is formed when two oceanic plates move
apart from each other, causing magma to ooze up from the mantle. This
magma solidifies to form volcanic rock.
4. The continental plate is lighter then the oceanic plate.