Continental Drift: Theory Explained By Alfred Wegener

BACKGROUND
Continental drift is a theory proposed by a scientist, Alfred Wegener in the twentieth century. The theory explained that all the continents was once joined as one, and through the course of millions of years, drifted apart from each other to form separate continents as we see it now.

THEORY
Before all the continents were separated, they existed as one supercontinent, Pangaea (Lovett, 2008), surrounded by a super ocean, known as Panthalassa. Movement of continents can be compared to the movement of icebergs on water. This is because earth is liquid inside. As the liquid moves, the crust moves with it, the tectonics plates move with it, causing the continents to move with it too. Figure 1: Supercontinent Pangaea

PROOF
Among
CONVERGENT BOUNDARIES Figure 3: Movement of Convergent Boundaries
Convergent boundaries occur when two plates move towards each other, resulting in one plate moving underneath the other plate, creating a subduction zone (Kerey, 2007). Whether or not a plate will be subducted depends on its density. As of today, it’s generally accepted that oceanic crust is denser than continental crust. The subducted plate is then eventually melted and destroyed by the immensely high temperature within the earth. When an oceanic crust meets another oceanic crust, island arcs, submarine volcanoes, and oceanic trenches are formed. On the other hand, when continental crust meets another continent crust, large mountain ranges are formed. A clear and magnificent example is the Himalayas. Finally, when two different crusts meet, the denser oceanic crust slides under the continental crust and is subducted, forming moderately sized mountain ranges such as the Andes.
Example of convergent boundaries are the boundaries between Eurasian plate and the Indian plate, and between Nazca plate and the South American plate.
2. DIVERGENT
Earthquakes occur along these points of tear, or faults. Example of divergent boundaries are the boundaries between the Arabian plate and the African plate, and between the Antarctic plate and the pacific plate.

3. TRANSFORM BOUNDARIES Figure 5: Movement of Transform Boundaries
Transform boundaries occurs when two plates slide pass each other horizontally. The sliding motion is not without friction, which causes stress to build up in both plates, and when it exceeds the threshold, huge amounts of energy are released causing earthquakes. Rocks at the boundary are destroyed, creating an undersea canyon. Contrary to the boundaries mentioned before, no magma is formed and no crust is neither destroyed nor formed. One very widely-known example is the San Andreas Fault, due to the sliding motion between the Pacific Plate and the North American Plate.

REFERENCE
Brian J. Skinner & Stephen C. Porter (1987). The Earth: Inside and Out. Physical Geology. John Wiley & Sons. Page 17.
Donald L. Turcotte & Schubert, G. (2002). Plate Tectonics. Geodynamics (2nd Edition). Cambridge University Press. Page