Examine the relevance of the plate tectonic theory in the understanding of the present day distribution of oceans and land masses   

Candidates should bring out the distribution of land masses and water bodies (oceans) in relation to tectonic plates

• It explains the movement and distribution of present day continents, ocean basins and land forms
• It proposes that the earth crust is divided into individual separate parts/tectonic plates by geochemical reactions and radioactivity in the earth’s interior. These float and move/glide on the top of Earth’s interior mantle.
• The movements of the tectonic plates results in the movement of continents /land masses and water bodies and change their positions relative to each other.
• Generally all plates move northwards, others like America move westwards while Africa, Europe, Asia, Australia move north eastwards.
• There are 3 types of plate movements/boundaries caused by convection currents which influence the distribution of continents i.e.

1. Divergent movements; caused by tectonic plates moving away from one another. These lead to faulting, rifting and warping of crustal land masses. On the sea floor, divergent movements produce under-water mountains known as the mid-ocean ridge for example the mid-Atlantic ridge and islands
2. Convergent movement; caused by tectonic plates moving towards one another. And as a result;­ continental land masses may move towards each other getting closer, collision may occur leading to folding and formation of fold mountains e.g. the Himalayas due to the collision of India and Asia.
3. Continents may move towards Oceanic plates causing subduction of denser simatic rocks. Collision of plates and subduction leads to formation of trenches , volcanic and fold mountains e.g. Nazca , Java and Tonga trenches etc.
4. Oceanic crust may move towards each other causing narrowing of Ocean Basins and continents move nearer leading to formation of trenches and volcanic arcs e.g. Pacific and Eurasia plates moved towards each other Marina trench and Japan volcanic arc were formed.