Over geological time, plate tectonics has shaped continents and ocean basins by constantly moving the large plates of Earth's crust. These movements cause continents to drift (continental drift), collide to form mountains (like the Himalayas), and split apart to create rift valleys. Ocean basins are formed and widened at mid-ocean ridges where plates move apart, and they are destroyed at subduction zones where one plate sinks under another.
MAJOR EVENTS OF EARTH'S SURFACE EVOLUTION
Formation of Earth (4.6 billion years ago):
The Earth formed from a cloud of dust and gas in the solar system, and heavy materials like iron sank to the center, forming the core.
Formation of Oceans (4.4 billion years ago):
As the Earth cooled, water vapor in the atmosphere condensed and formed oceans, creating a watery world.
The Great Oxidation Event (2.4 billion years ago):
Photosynthetic organisms began producing oxygen, which gradually accumulated in the atmosphere and oceans, changing the planet's atmosphere and triggering significant evolutionary shifts.
The Cambrian Explosion (541 million years ago):
A period of rapid diversification of life, particularly marine life, leading to the appearance of a wide variety of new animal groups.
Continental Drift and Plate Tectonics:
The Earth's surface is divided into tectonic plates that move and interact over time, causing mountain building, earthquakes, and volcanic activity. For example, the supercontinent Pangea existed 240 million years ago and began to break apart about 200 million years ago.
Mass Extinctions:
Several events have led to mass extinctions of life on Earth, such as the Permian-Triassic extinction, which wiped out 96% of all marine species.