Tectonic Processes
1. Fold moutains are actually formed by crust which have been uplifted and folded
by compressional forces. This occurs along convergent plate boundaries where 2
plates move towards each other, between continental plates or between an oceanic
and a continental plate. The crust and the rocks get bent and crumpled, and
massive layers of Earth's crust gets uplifted as a result, forming spectacular fold
mountains.
2.
3. Faulting is part of the process which causes volcanism and continental drift. As
the Earth's crust is stretched or shoved during the seafloor spreading process, the
rocky material of which it is made will fracture. These fractures are called
"faults". The different patterns of faulting provide evidence of the stress and
strain, or the pushing and shoving the crust is undergoing.
4. Thrust fault:
Thrust faults occur in the Los Angeles area because the San Andreas Fault bends
to the west causing some thrust faulting instead of strike-slip faulting. A thrust fault is a
particular type of fault, or break in the fabric of the Earth's crust with resulting movement
of each side against the other, in which a lower stratigraphic position is pushed up and
over another. This is the result of compressional forces.
Reverse Fault/Normal Fault:
Rift Valley:
In geology, a rift valley is a valley created by the formation of a rift. The Great Rift
Valley is the most famous of the world's rift valleys. Rift valleys are produced by
tensional tectonic forces which occur at divergent plate boundaries. Rift valleys typically
appear as a downdropped graben between a pair of faults, or vertical Earth movements.
Rift valleys are often associated with and flanked by volcanoes.
Horst:
In physical geography and geology, a horst is the raised fault block bounded by normal
faults. The raised block is a portion of the Earth's crust that has remained stationary while
the land has sunk on either side of it or has been crushed by a mountain range against it.
5. Diastrophism is a general term that refers to deformation of the Earth's crust. The
term covers movement of solid crust material. movements cause rock to be bent
or broken as a result of pressures exterted by plate tectonics or the rise of magma
from below.
6.
A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by
plate tectonics. This uplifting of the ocean floor occurs when convection currents beneath
the ocean bed force magma up where two tectonic plates meet at a divergent boundary.
The mid-ocean ridges of the world are connected and form a single global mid-oceanic
ridge system that is part of every ocean, making the mid-oceanic ridge system the longest
mountain range in the world, whose total length is ~60,000km.
7.
Subduction zones mark sites of convective downwelling of the Earth's lithosphere.
Subduction zones exist at convergent plate boundaries where one plate of oceanic
lithosphere converges with another plate and sinks below into the mantle. It is at
subduction zones that the Earth's lithosphere, oceanic crust, sedimentary layers, and
trapped water are recycled into the deep mantle.