Plate tectonics is a plausible theory presented by Earth Scientists to explain the formation of continents and oceans and the various landforms on Earth.

Plate Tectonics Theory:
The theory of plate tectonics suggests that the Earth's lithosphere (the rigid outer layer made up of the crust and upper mantle) is divided into several large and small plates that are continuously moving. These plates float on the semi-fluid asthenosphere beneath them.

Continental Drift:
The theory of plate tectonics builds upon the earlier theory of continental drift proposed by Alfred Wegener in the early 20th century. Wegener suggested that all the continents were once joined together in a single supercontinent called Pangaea and have since drifted apart. This movement of continents is due to the movement of the underlying tectonic plates.

Tectonic Plates:
The Earth's lithosphere is divided into several major tectonic plates, including the Eurasian Plate, North American Plate, Pacific Plate, African Plate, etc. These plates are constantly moving and interacting with each other at their boundaries.

Plate Boundaries:
There are three main types of plate boundaries:

1. Divergent Boundaries: These boundaries occur where two plates move apart, creating a gap. The magma from the asthenosphere rises to fill the gap, solidifies, and creates new crust. This process is known as seafloor spreading and leads to the formation of mid-oceanic ridges.

2. Convergent Boundaries: These boundaries occur where two plates collide. Depending on the type of plates involved, three types of convergent boundaries can form:
- Oceanic-Continental: When an oceanic plate collides with a continental plate, the denser oceanic plate is subducted (goes beneath) the continental plate. This leads to the formation of deep-sea trenches, volcanic arcs, and mountain ranges.
- Oceanic-Oceanic: When two oceanic plates collide, the denser plate subducts beneath the other, leading to the formation of island arcs, volcanic activity, and sometimes the creation of new islands.
- Continental-Continental: When two continental plates collide, neither subducts due to their low density. Instead, the collision leads to intense folding, faulting, and uplift, resulting in the formation of mountain ranges.

3. Transform Boundaries: These boundaries occur where two plates slide past each other horizontally. As the plates move, stress builds up along the boundary, and when it is released, it causes earthquakes. The San Andreas Fault in California is an example of a transform boundary.

Effects on Landforms:
The movement of tectonic plates and the interaction at plate boundaries have several effects on the Earth's surface, leading to the formation of various landforms such as:

- Mountain Ranges: The collision of two continental plates at convergent boundaries leads to the formation of large mountain ranges like the Himalayas.
- Rift Valleys: Divergent boundaries can create rift valleys as the plates move apart, forming a gap that is filled with magma and eventually becomes a valley.
- Volcanoes: Volcanic activity is often associated with plate boundaries. When one plate subducts beneath another, it can melt, leading to the formation of magma chambers and volcanic

B