PLATE BOUNDARY, PLATE MOVEMENT AND RESULTANT LAND FORMS

PLATE BOUNDARY, PLATE MOVEMENT AND RESULTANT LAND FORMS

Plate tectonic theory is a most important 1960s. Plates move over the asthenosphere which is viscous region. The plates move either opposite side or towards or pass each other. Plate boundaries are very important because all tectonic activities occurs along this such as volcanisms, earthquake, oceanic crust, drifting of plates etc.

MOVEMENT OF PLATES

Plate boundaries are divided into three categories as follows:

1. Conservative Plate Boundary
2. Divergent Plate Boundary
3. Convergent Plate Boundary

TYPE OF PLATES

TRANSFORM BOUNDARY:

When two plates pass simply each other along the fault is called Transform Boundary. It forms without creating and destroying the tectonic crust. It moves horizontally. When they pass each other, they get stress and exceed the strain threshold of rock on either side. This plate is also known as Conservative plate boundary.

TRANSFORM BOUNDARY

EXAMPLE:

    .      A notable example of this type of plate boundary is the San Andres Fault in the Western coast of North America where the pacific oceanic plate and North American continental plates move relatively each other .the pacific plate is moving from northwest side of North America,Alpine fault in New Zealand,The North Anatolian fault in turkey,The Mendocino Fracture zone offshore Northern California.

RESULTANT LAND FORM: 

·      Transform fault: Two plates slide each other in horizontal manner. It is a type of strike-slip fault. It moves 100 – 150 km deep along the mid oceanic ridge. The North Anatolian fault and San Andres fault are continental type of boundary.

DIVERGENT BOUNDARY:-

This are also called constructive plate margins or accreting plate boundaries. Plate margin represents the end part of the plate while plate boundary is an area between two plates.When two plates move in opposite direction and the empty space is filled with up welling magma creates new crust. There is continuous up welling of magma which is formed new crust.This plate boundary is also called constructive boundary because of the movement of two plates in opposite direction, up welling of magma spreads over the surface. After cooling and solidification forms a new crust.

EXAMPLE:-

a)  Mid Atlantic ridge

b) The east pacific rise

c)  East African Great Rift Valley

RESULTANT LAND FORM:-

      MID OCEANIC RIDGE:-

The North and South American plates Eurasia and Africa moves in opposite direction forming “S” shaped Atlantic ridge.

MID OCEANIC RIDGE 

OCEANIC RISE:- When molten magma spreads over the ocean floor at faster rate, forming a gentle slope land form is called oceanic rise. The east pacific rise is typical example of oceanic rise which formed due to movement of Nazca plate and pacific oceanic plate.  

ORIGIN OF OCEAN:-The Mid Atlantic ridge formed due to movement of African plate and American plate. On the other side the movement of African plate and Arabian plate, originating red sea along the ridge.

ORIGIN OF RED SEA

RIFT VALLEY:- Subsiding of rock block is due to the movement of plate in opposite side is known as rift valley. THE GREAT RIFT VALLEY IN AFRICA is the typical example of it. 

EAST AFRICAN GREAT RIFT VALLEY

CONVERGENT BOUNDARY:

when two plate moves toward each other and more denser 

plate collides with less denser plate, the more denser 

oceanic plate is typically underneath of less denser 

continental plate, forming a subduction  zone is called 

convergent boundary. This boundary is also called 

destructive boundary.

CONVERGENT BOUNDARY

SUBDUCTION ZONE: When the oceanic crust is thrust underneath of continental plate at 45 degree angle is called subduction zone or Benioff zone.

SUBDUCTION ZONE

OBDUCTION ZONE: Sometime the continental plate is moved under the oceanic plate is called obduction zone.

OBDUCTION ZONE

EXAMPLE: The west coast of South America where Nazca plate is being subducted beneath the continental South American plate.

TYPE OF CONVERGENT BOUNDARY and RESULTANT LAND FORM

Convergent boundary is typically three type i.e. 

Continental-oceanic boundary: A volcano under the ocean floor is typically resulting of it. The continental plate of west coast of America is subducted beneath the oceanic plate of Nazca plate, forming a volcanic mountain building. Other example is in North America the cascade mountain range.

CASCADE RANGE

CONTINENTAL - OCEANIC CONVERGENCE PLATE BOUNDARY

Continental -continental boundary

When two continental plates collides either buckle or compress or delve under or overrides the other. When the Indian plate collides with Eurasian plate and the Indian plate is being thrust under a portion of Eurasian plate, lifting it and forming the Himalayas and the Tibetan plateau.

RISE OF HIMALAYAS AND TIBETAN PLATEAU

Oceanic -oceanic boundary

When two oceanic plates creates island arc as one plate is being subducted underneath other. Notable example of this type plate is Japan and Aleutian islands in Alaska

Plates tectonics is a significant concept which explained major feature of the earth and provided satisfactory explanation.

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