The crust is the hard, outer layer of the Earth that forms the land and the ocean floor. The continental crust (the lane masses) is the oldest and thickest part and made up mostly of silica and aluminium. The oceanic crust, made up mostly of silica and magnesium, is around 200 million years old.
Early on in Earth’s history, minerals began to form. Lighter minerals floated up toward the surface and formed a thin crust of rock around the outside of the planet (which we now live on top of). If Earth was the size of a plum, the rocky crust would be a bit like the thin purple skin. If we want to see below the surface, we can drill down into the crust for thousands of meters.
The crust is mostly made of minerals such as quartz, feldspar and mica. These are the shiny crystals in granite rocks, which you can see in the southwest of Kenya. Over long periods of time these minerals break down into small pieces and are carried around by winds, currents and waves to form soft sediments like sand. Look out for sediments when you are by a river, a lake or a beach.
The crust is made up of huge blocks of rock that move around the Earth’s surface very slowly – as slowly as your fingernails grow. The movement of these plates over millions of years causes continents to split apart and smash together. Right now, East Africa is splitting into two pieces along the Great Rift Valley and one day in the distant future, the rift may be flooded by the sea.
In between the core and the crust is a hot, squishy body of rock called the mantle. The mantle is mostly made of a mineral called olivine, which is a beautiful shade of green. The hot mantle has currents that flow like treacle. These slow currents push the plates of rock around at the surface.
Picture Credit : Google