The Early EarthThe Earth, formed around 4.6 billion years ago started as gases and rocks in space, which began to gravitationally attract more matter. An atmosphere was created by steam escaping from the crust and gases released from volcanic eruptions.
There's a theory that around 4.4. billion years ago, an object the size of Mars bounced off the newly formed Earth. This object blew off enough material to create the moon and even tilted the Earth onto an axis. As the molten Earth cooled down from all the collisions, water condensed from the atmosphere to form oceans with the addition of water vapour from volcanic eruptions. It is assumed much of the Earth’s water came from comets containing ice. |
The Earth is made of 3 layers : the crust, mantle and the core.
Crust Depending on where on the Earth, the crust contains different thickness. Under oceans the crust is 5km to 10km thick, while under continents it is 32km to 70km thick. It is made up of iron, oxygen, silicon, magnesium, sulfur, nickel and has traces of aluminium, calcium and other elements. Mantle The mantle is 2,900km thick and it consists of rocks which are 'plastic', solid rocks that can flow like liquid. The upper mantle is 1000˚C, but the inner mantle is 3000˚C. It is made up of silicates of iron and magnesium, sulphides and oxides of silicon. Outer Core The outer core is 2,200km thick and is made up of super heated liquid molten lava containing iron and nickel. This is the second hotter layer and has a range of 4,000 - 5,000˚C. Inner Core The inner core is 1,300km thick and is the hottest layer at 9,800˚C. This layer contains solid rock, iron and nickel. Lithosphere The lithosphere is composed of the crust and upper mantle. It's 2km - 130km thick depending on which part of the Earth it's measured. The lithosphere is broken up into tectonic plates which move around the Earth creating mountains, volcanoes, earthquakes, etc... It's made up of continental crust and oceanic crust. Continental crust - thick part of Earth’s crust that forms the land. Oceanic crust - thin part of Earth’s crust that is found under oceans. Asthenosphere It's made up of upper layer of mantle and is located below the lithosphere. At 70km - 250km thick, the asthenosphere is made up of partially molten rock (because of pressure and heat), allowing the tectonic plates on it to ‘float’ around the Earth. |
The Earth is made up of minerals, crystals and rocks.
Minerals : Inorganic, natural solids formed from single elements or combinations of elements in the earth’s crust. Crystals : Natural solid substance that has a definite shape. All minerals are made of tiny crystals. Rocks : Organic, natural solids formed from a mineral or combination of minerals. There are three types of rocks : Igneous rock When melted minerals or magma, cool down and harden Sedimentary rocks When pieces of rock and minerals become cemented together Metamorphic rock When existing rocks are slowly changed by heat and pressure |