The formation of Earth's crust protected the inner layers of Earth from the high-energy particles in space, reducing the temperatures of the mantle and the core.
地壳的形成保护了地球的内层不受太空中高能粒子的影响，降低了地幔和地核的温度。
Above the mantle, Earth has two kinds of crust.
在地幔之上有两种地壳。
Four and a half billion years ago the Earth was about sixty percent formed, though it did have a differentiated core, crust and mantle.
45亿年前，地球大约只有现在百分之六十，尽管它确有能够区分的地核，地壳和地幔。
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