A new theory:
A new theory Evidence of continental drift and ocean-floor spreading caused many older theories about the Earth to be discarded.
A new theory about the evolution of the Earth began to develop, called Plate Tectonics.
A plate is the moving, irregular-shaped slabs that fit together like paving stones to form the surface layer of the Earth
Lithospheric Plates:
Lithospheric Plates According to the theory of plate tectonics, the topmost solid part of the Earth, called the lithosphere, is made of a number of plates.
The plates contain a thin layer of crust above a thick layer of relatively cool, mantle rock.
Plates usually contain both oceanic and continental crust
Lithospheric Plates of the World:
Lithospheric Plates of the World
Plate Boundaries:
Plate Boundaries There are 3 types of plate boundaries
A) Divergent (also called constructive boundaries)
B) Convergent (also called destructive boundaries)
C) Strike-slip (also called conservative boundaries)
Divergent Boundary:
Divergent Boundary Divergent boundaries occur at midocean ridges.
Plates move apart or diverge at these ridges, as new ocean floor is formed. That’s why they are also known as constructive boundaries, because new ocean floor is constantly being made.
Convergent Boundary:
Convergent Boundary Convergent boundaries have trenches.
Plates come together at these trenches and older crust is destroyed (destructive)
Strike-Slip Boundary:
Strike-Slip Boundary Formed by a lateral fault
Two plates grind together and slip past each other horizontally.
No new plate material is made, nor is any destroyed (hence the name, conservative).
Earthquakes are prone to occur along strike-slip boundaries.