Key Points

In 1912, Alfred Wegener proposed that all continents once formed a single supercontinent named Pangaea, which was surrounded by a mega-ocean called Panthalassa.

About 200 million years ago, Pangaea began to split into two large landmasses: Laurasia in the north and Gondwanaland in the south, which later broke into today's continents.

The coastlines of Africa and South America show a remarkable and unmistakable match, suggesting they were once joined. This fit is nearly perfect when matched at the continental shelf margin.

Similar ancient rock formations and glacial deposits called tillite are found on different continents like South America, Africa, India, and Australia, indicating a shared geological history.

Fossils of land-based species like Mesosaurus and Lemurs are found on continents now separated by vast oceans, suggesting these landmasses were once connected.

Wegener suggested that the pole-fleeing force due to Earth's rotation and tidal forces from the sun and moon caused the drift. However, most scientists considered these forces to be inadequate.

In the 1930s, Arthur Holmes proposed that convection currents in the mantle, driven by heat from radioactive elements, were the driving force behind the movement of continents.

Proposed by Harry Hess in 1961, this theory states that new oceanic crust is formed by volcanic eruptions at mid-oceanic ridges and moves outwards, pushing the continents apart.

Evidence includes the fact that rocks are youngest at the mid-oceanic ridges and get progressively older away from them, and the presence of magnetic stripes parallel to the ridges.

Introduced in 1967, this theory states that the Earth's lithosphere is divided into massive, rigid plates that move over the asthenosphere. It is the plates that move, not just the continents.

The Earth's lithosphere is divided into seven major plates, such as the Pacific and Eurasian plates, and several minor plates, including the Nazca and Arabian plates.

At divergent boundaries, plates pull away from each other, creating new crust. These are known as spreading sites, with the Mid-Atlantic Ridge being a key example.

At convergent boundaries, plates collide, and one plate dives under the other in a process called subduction, destroying crust and forming mountains or trenches.

At transform boundaries, plates slide horizontally past one another. The crust is neither created nor destroyed at these locations.

The Indian plate drifted northward from the southern hemisphere and collided with the Eurasian plate about 40-50 million years ago, leading to the formation of the Himalayan mountains.