Odin creates the sky from the skull of Ymir

"Of Ymir's flesh | the earth was fashioned,
And of his sweat the sea;
Crags of his bones, | trees of his hair,
And of his skull the sky.
Then of his brows | the blithe gods made
Midgard for sons of men;
And of his brain | the bitter-mooded
Clouds were all created."