Earth's History

Sara Qualey 8D

Earth's Origins

The Earth was formed 4.54 billion years ago by enormous rocks colliding in the giant disc shape cloud of material. Gradually, the amount of rocks built up to create planet Earth. The rocks that formed the Earth were molten. Over time, the rocks formed layers and the crust cooled. The heaviest materials sunk to the bottom and the lightest materials stayed on top.

The Earth's Materials

Oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium are the main elements that make up about 99% of Earth's crust.

The Four Layers of Earth

The Earth is composed of 4 layers; the crust, mantle, outer core, and inner core. The inner core is made of solid iron and the outer core is made up of liquid iron and nickel. The core is the hottest part of Earth. The mantle is the 3rd layer. It takes up more than 2/3 of Earth's mass. The mantle is split into two parts. The lower part is liquid and has the consistency of silly putty. The upper part is solid. The mantle as a whole is mainly made of silicon, iron, magnesium, oxygen, and aluminum. The crust is the outermost layer of Earth. 99% of the crust is made of oxygen, sodium, silicon, iron, potassium, calcium, magnesium, and aluminum. Each layer is different. The coldest layer is the crust and the farther you go down, the hotter it gets. This is also true with pressure. The farther you go down, the more pressure there is. This is why the inner core is solid.

How Do The Layers Affect The Earth's Crust

The outer core has a magnetic field around the Earth that keeps radiation out. In the mantle, hot lava comes up from the core and causes the tectonic plates to move. This can affect earthquakes, mountains, volcanoes, etc.

Plate Tectonics

Tectonic plates are large slabs of Earth's outer layer that are broken up. These plates move around and hold continents and oceans. These plates cause earthquakes and create mountains and trenches. Plate tectonics are all over the Earth. The three kinds of plate tectonic boundaries are divergent, convergent, and transform. Convergent boundaries are pushing towards each other, divergent boundaries are plates that move apart from each other, and transform boundaries are plates that move past each other. An example of convergent boundaries is the boundary between the Eurasian Plate and Iridian Plate. A divergent boundary- between the African and Arabian Plates, and a transform boundary- the Pacific and Australian Plates.