[Geography Notes] on Tectonic Landform Pdf for Exam

Tectonic landforms are a typical geomorphic feature. This landform is generated by the process of surface deformation that is related to the active tectonic structures. Morphogenetic processes are moreover related to regional stress fields that are driven by the lithospheric plates by their relative motion. 

These landforms are particularly quite intense along with the different types of plate margin regions like – convergent, divergent and transform or the conservative types. Crustal deformation associated with the plate tectonics is responsible for the main large-scale morpho-structural elements of the Earth which include the active orogens, the subsiding sedimentary basins, also the extensive plateaus, and the oceanic basins, the mid-ocean ridges, and the oceanic trenches. 

Divergent Boundary Landforms

In these plate tectonics, there is a divergent boundary or a divergent plate boundary which is also known as the constructive boundary or an extensional boundary is a type of linear feature that is present between the two tectonic plates which are moving apart.  

Divergent boundaries situated within the continents originates as rifts, thereafter it becomes rift valleys. The active most divergent plate boundaries occur between the oceanic plates, existing as mid-oceanic plates.  The divergent boundaries also give rise to volcanic islands that occur when the plates shift to produce gaps when the magma rises to fill.

Convergent Boundary Landforms

A convergent boundary or the destructive boundary is a place on Earth where more than two lithospheric plates collide with each other. One of the plates slides under the other and this process is called subduction. This subduction zone is marked by a plane where frequent earthquakes occur, this zone is called the Wadati-Benioff zone. These types of collisions happen on large scales which can lead to volcanism, orogenesis, earthquake, destruction of the lithosphere, and deformation. The convergent boundaries normally occur between the oceanic-oceanic lithosphere, oceanic-continental lithosphere, and also occurs between the continental-continental lithosphere.

Landforms Caused by Plate Tectonics

The activity which occurs when the two tectonic plates come in contact with each other might have a major impact on the landscape of the Earth, this is a known fact. 

Though the process can take millions to zillions of years to form the landforms by plate tectonics, it is all worth the while offer as some of these get formed into the most impressive natural land features in the world. 

Some of These Land Features are as Follows:

Fold Mountains

The compressional forces that exist in a convergent plate boundary, wherein two plates collide with one another, can create fold mountains. This also involves the collision of any two continental plates or collision of the continental plate and an oceanic plate that forces the sedimentary rocks to rise upwards into a series of folds.

Ocean Trenches

Ocean trenches form in different kinds of convergent plate boundaries. Here a continental and an oceanic plate converge also two oceanic plates can also converge. The oceanic plates are quite denser than that of continental plates and so they plunge beneath them, or “subducts” each other. 

Island Arcs

With the subduction process, an oceanic plate converges with another oceanic plate which can lead to volcanoes that are being formed parallelly like a trench. The volcanic debris and lava which are built upon the ocean floor over a million years eventually result in forming a formerly submarine volcano that rises above sea level to create an island arc. 

Ocean Ridges

At divergent boundaries, the plates move apart from each other, which creates a new crust, while the magma is being pushed up from the mantle. The mid-ocean ridges result from this volcanic swelling and from the eruptions occurring along the divergent boundary. 

Destructive Plate Boundary Landforms

At the area of destructive plate boundary which is also known as the convergent plate boundary – the plates move towards one another. This usually involves the oceanic plate and this is a continental plate. The movement can also cause earthquakes and the occurrence of volcanoes. 

When the plates collide, the oceanic plate forcefully gets beneath the continental plate. This event is known as subduction which results in the formation of an ocean trench. This occurs because the oceanic plate is heavier than the continental plate. When the plate sinks into the mantle it melts to process into magma. The pressure of magma builds up under the Earth’s surface. The magma escapes through the rock cracks and when it rises up through a composite volcano, is known as a stratovolcano.