The continental drift theory, proposed by Alfred Wegener in the early 20th century, suggests that the Earth’s continents were once joined together in a single landmass called Pangaea. According to this theory, over millions of years, the continents gradually drifted apart to their current positions. Wegener supported his hypothesis by pointing out the remarkable fit of the coastlines of South America and Africa, as well as the presence of similar fossils and rock formations on both continents.

However, Wegener’s theory faced significant skepticism and criticism at the time, as he was unable to provide a convincing mechanism for the movement of continents. It was not until the mid-20th century that the plate tectonics theory emerged, which provided a more comprehensive explanation for the movement of Earth’s lithospheric plates.

Plate tectonics theory states that the Earth’s lithosphere, which consists of several large and numerous small plates, is divided into rigid sections that float on the semi-fluid asthenosphere beneath. These plates are in constant motion, driven by the convective currents in the underlying mantle. There are three main types of plate boundaries: divergent, convergent, and transform.

Divergent boundaries occur where plates move away from each other, creating a gap that allows magma to rise and form new crust. This process is responsible for the formation of mid-ocean ridges, such as the Mid-Atlantic Ridge.

Convergent boundaries occur when plates collide. Depending on the type of crust involved, three scenarios can occur: oceanic-oceanic convergence, oceanic-continental convergence, and continental-continental convergence. In oceanic-oceanic convergence, one plate subducts beneath the other, forming a deep ocean trench and volcanic arcs. In oceanic-continental convergence, the denser oceanic plate subducts beneath the less dense continental plate, leading to the formation of mountain ranges and volcanic activity. In continental-continental convergence, neither plate subducts, resulting in the collision and uplift of crust, forming large mountain ranges.

Transform boundaries occur where plates slide past each other horizontally. These boundaries are characterized by intense seismic activity, as the plates grind against each other. The San Andreas Fault in California is a well-known example of a transform boundary.

Plate tectonics theory not only explains the movement of continents but also provides a framework for understanding various geological phenomena, such as earthquakes, volcanic activity, and the formation of mountain ranges. It has revolutionized our understanding of Earth’s dynamic nature and continues to be a fundamental concept in geology.