Continents, Major Oceans & Plate Tectonics
Planet Earth's surface is structured into seven continental landmasses (Asia, Africa, North America, South America, Antarctica, Europe, and Australia) and five interconnected oceans (Pacific, Atlantic, Indian, Southern, and Arctic). Modern physical geomorphology is explained by Alfred Wegener's Continental Drift Theory and the Plate Tectonics theory formulated in the 1960s. The Earth's lithosphere is divided into major and minor tectonic plates that float atop the asthenosphere. Plate boundaries are classified as divergent (seafloor spreading along Mid-Atlantic Ridge), convergent (subduction zones and fold mountain formation), or transform (San Andreas Fault). The Pacific Ocean basin contains the Circum-Pacific 'Ring of Fire', an active zone hosting over 75 percent of the world's active volcanoes and seismic epicenters.
Key Concepts & Examination Highlights
- Asia is the world's largest continent by both land area (approx. 44.58 million sq km) and human population (over 4.7 billion).
- The Pacific Ocean is the largest and deepest ocean, containing the Challenger Deep in the Mariana Trench (approx. 10,994 meters deep).
- The Mid-Atlantic Ridge is a massive submarine mountain range formed by divergent plate movement between the Eurasian, North American, and South American plates.
- The Pacific 'Ring of Fire' is a 40,000-kilometer horseshoe-shaped tectonic belt where the majority of global earthquakes and volcanic eruptions occur.