Continental and Oceanic Crust

The continental and oceanic crust constitute the external surface of our planet. They are the outermost layer of the Earth as they are parts of the lithosphere. The crust is constantly being formed, destroyed and rebuilt by geological processes happening inside the mantle. It consists of volcanic rocks on top of which layers of softer sedimentary rock and organic sediment rest. On average, it is estimated that it is 22 miles (35 km) deep and it gets slightly thicker every year as more molten rocks constantly come out from within the Earth.

Continental Crust

It is the geological layer which is constituted by dry land. It is made up largely of rocks called granite, which is not only igneous (volcanic) but also plutonic rock. Granite is the pink, black, and grey rock that came out of active volcanoes hundreds of millions of years ago, cooling off and solidifying under the earth surface. It is characterized by being the hardest rock on Earth. Today, melted rocks from beneath this crust still rise to the surface through volcanic activities and tectonic plates movement as they solidify into granite rocks.

Oceanic Crust

It is the layer of geological material located under the oceans. It consists of rocks called basalts. They are black, dense heavy rocks, which were spewed out of underwater volcanoes. Although they are not easily spotted, there is a lot of them in the ocean floors. Oceanic crust is much younger than continental crust, because the former is constantly being destroyed and reshaped anew by these volcanoes, adding new rocks to it. Continental crust rocks are about 3.7 billion years old, whereas oceanic crust basalt is about 100 million years of age.