So there is a lot to learn when it comes to the surface of the earth and its crust and core, however it’s also pretty cool! Well technically it’s extremely hot, but you get my drift.
Firstly we’re going to take a look at the Earth’s crust.
The outermost layer of the Earth is called the crust. The dense core of the Earth is surrounded by a mantle. The mantle is surrounded by a thin outer layer called a crust. A thin layer of gases called the atmosphere surrounds the crust.
The crust is very thin (in relation to the size of Earth anyway) ranging from five – 70 km. The average thickness of the crust under the ocean is six km and the average thickness under continents is 35 km.
The Earth’s atmosphere is the thin layer of gases which surrounds the crust, mantle and core. About 80% of the air in the atmosphere lies within 10 km of the Earth’s surface. The remaining 20% is estimated to be within 100 km from the Earth’s surface, but the exact distance is not known because it is difficult to identify exactly where our atmosphere ends and space begins.
Although there are several theories, it is thought that volcanoes released carbon dioxide, water vapour and nitrogen. The carbon dioxide formed the early atmosphere. The water vapour eventually condensed, fell as rain and formed oceans.
Now that we know a little bit more about the crust and the atmosphere of the Earth, let’s have a look at the mantle and the core.
The Earth’s crust and the outer mantle are split into many large pieces. These large pieces are called tectonic plates. Radioactive atoms decay in the core which release energy. This energy creates convection currents, which control the movement of the tectonic plates. Forces between the tectonic plates cause mountain formation, earthquakes and volcanic eruptions.
The Earth’s mantle is much more dense than the Earth’s crust. It behaves like a solid but parts of it can flow very slowly, like a liquid. Deep within the Earth, radioactive decay produces vast amounts of energy which heat up the mantle.
Minerals in the mantle expand and rise to surface as they become less dense. Cooler, more dense minerals sink to take their place. These movements create forces called convection currents, which move tectonic plates slowly across the Earth.
Even though we now know a lot about tectonic plates, it is still difficult to predict exactly when an earthquake might take place. This is simply because we can’t know when tectonic plates will slip past each other.
When the boundaries of tectonic plates meet, forces build up which can cause the plates to buckle to become mountains, separate to form volcanoes or suddenly slip past each other to cause earthquakes.
So although we can predict earthquakes to some extent by measuring the temperatures of rocks (which heat up before an earthquake), we can’t know exactly when the plates will move.
Scientists must try to predict when an earthquake might happen, because earthquakes can be very dangerous. Markers placed across plate boundaries can be measured by GPS to detect movement. Infrared satellites measure the temperatures of rocks, which heat up before an earthquake.
The Earth’s core is formed from the elements nickel and iron, and has a radius of approximately 3500 km, which is about 50% of the Earth’s radius. The inner core is solid and the outer core is liquid.
The density of the Earth overall is much greater than the density of the rocks that make up the crust so the core must be made up of denser material than the crust.