Made by Patrick Smyth
Formation of the earth
- The Earth is thought to have been formed about 4.6 billion years ago by collisions in the giant disc-shaped cloud of material that also formed the Sun. Gravity slowly gathered this gas and dust together into clumps that became asteroids and small early planets called Planetesimals. Planetesimals means a minute planet and if lots of these come together it create a bigger planet. In our planet there are 4 main layers: the crust, the mantle, the inner core and the outer core. The layer we live on is the crust and is the thinnest layer at 60km. The layer below that is the mantle which is the widest layer on earth at 2900 km. The layer below that is the outer core which surrounds the inner layer and this layer is a liquid layer. The centre of the earth is called the inner core and it is the hottest tempriture at 5500 degrees! This is a diagram of the earth below
Alfred Wegener proposed the theory of continental drift at the beginning of the 20th century. His idea was that the Earth's continents were once joined together, but gradually moved apart over millions of years. It offered an explanation of the existence of similar fossils and rocks on continents that are far apart from each other. But it took a long time for the idea to become accepted by other scientists. His evidence for his theory was that:
- the same types of fossilised animals and plants are found in South America and Africa
- the shape of the east coast of South America fits the west coast of Africa, like pieces in a jigsaw puzzle
- matching rock formations and mountain chains are found in South America and Africa
The one super contenent was called Pangea
That is what the earth looked like in the past but in the future the earth may look completely different because of the tectonic plates.
- A tectonic plate is a massive, irregularly shaped slab of solid rock, generally composed of both continental and oceanic lithosphere. Plate size can vary greatly, from a few hundred to thousands of kilometers across; the Pacific and Antarctic plates are among the largest.This is a map of the tectonic plates on the earth today.