definition of crust on the earth
The Earth's crust is an extremely thin layer of rock, like the skin of an apple in relative terms. It amounts to less than half of 1 percent of the planet. But the crust is exceptionally important, and not just because we live on it.ceanic crust covers about 60 percent of the Earth's surface. Oceanic crust is thin and youngâno more than about 20 km thick and no older than about 180 million years. Everything older has been pulled underneath the continents by subduction.