The new earth, freshly torn from its parent sun, was a ball of whirling gases, intensely hot, rushing through the black spaces of the universe on a path at a speed controlled by immense forces. Gradually the ball of flaming gases cooled. The gases began to liquefy, and Earth became a molten mass. The materials of this mass eventually became sorted out in a definite pattern: the heaviest in the center, the less heavy surrounding them, and the least heavy forming the outer rim. This is the pattern which persists today††a central sphere of molten iron, very nearly as hot as it was 2 billion years ago, an intermediate sphere of semi-plastic basalt, and a hard outer shell, relatively quite thin and composed of solid basalt and granite.