The Changing World

The Earth’s lithosphere consists of plates of different sizes. These can be grouped according to how they move in relation to each other.

The Indian Plate collided with the Eurasian Plate 60 million years ago, resulting in the formation of the Himalayas.
Since the two plates are still colliding and compressive forces act on them, the Himalayas keep growing slowly
at a rate of 1 cm per year.

From the 1960s, research vessels began to map the seabed
and realised that it was gradually expanding. From this and the theory of continental drift, the theory of plate tectonics was born. According to this theory, the Earth’s lithosphere, which is the outermost, solid layer of Earth, consists of several major and minor plates that are moved by forces within the Earth.

Today we know of seven major tectonic plates and a number of other, smaller ones, which all move in relation to each other. The seven major tectonic plates are: the African plate, the Eurasian plate, the North American plate, the South American plate, the Pacific plate, the Indo-Australian plate and the Antarctic plate. Some of the plates comprise only oceanic crust while others comprise oceanic and continental crust as well.

Each tectonic plate moves at different speeds. Some are approaching each other, while others are moving away
or slipping past each other. Oceans form at divergent plate boundaries, while convergent plate boundaries give rise to long mountain ranges. The most massive volcanic eruptions and earthquakes occur at tectonic plate boundaries.

Types of plate boundaries:

<− −>  divergent       −> <−  convergent       ¯¯—  transform