jarðsöguna

Jarðsagan, which translates to Earth's history, is the chronicle of our planet from its formation to the present day. This vast period encompasses the development of its physical structure, atmosphere, oceans, and the evolution of life. Scientists piece together this history through various disciplines including geology, paleontology, and astronomy.

The Earth formed approximately 4.54 billion years ago from the solar nebula. The early Earth was a molten ball that gradually cooled, allowing for the formation of a solid crust and the release of volcanic gases that created the initial atmosphere. Water, likely delivered by comets and asteroids, accumulated to form the primordial oceans.

The Hadean, Archean, and Proterozoic eons represent the Precambrian time, a period characterized by the origin of life, the development of photosynthesis, and the gradual oxygenation of the atmosphere. Single-celled organisms dominated this era.

The Phanerozoic Eon, starting around 541 million years ago, is divided into the Paleozoic, Mesozoic, and Cenozoic eras. This is the time of complex life. The Paleozoic saw the Cambrian explosion of biodiversity, the colonization of land by plants and animals, and the formation of supercontinents. The Mesozoic, often called the Age of Reptiles, was dominated by dinosaurs. The Cenozoic, the current era, is known as the Age of Mammals and has witnessed the rise of primates and ultimately, humans. Throughout jarðsagan, major events like mass extinctions have reshaped the course of life on Earth, highlighting the dynamic nature of our planet's past.