Snorri Sturluson’s “Gylfaginning”, chapter 8, part I
8. The World is Created from Ymir’s Body
Gangleri answered, ‘What did Bor’s sons do next, if you believe they are gods?’
High said, ‘It is no small matter to be told. They took Ymir and they moved him into the middle of Ginnungagap and made from him the world. From his blood they made the sea and the lakes. The earth was fashioned from the flesh, and mountain cliffs from the bones. They made stones and gravel from the teeth, the molars and those bones that were broken.’
Then Just-as-High said, ‘With the blood that gushed freely from the wounds, they made the sea, and by fashioning that sea around, they belted and fastened the earth. Most men would think it impossible to cross over this water.’
Then Third added: ‘They also took his skull and from it made the sky. They raised it over the earth and under each of the four corners they placed a dwarf. These are called East, West, North and South. Then they took the embers and sparks shooting out from Muspellsheim and flying randomly. These they placed in the middle of the Ginnung Sky, both above and below, to light up heaven and earth. They fixed places for all these burning elements. Some were placed up in the heavens, whereas for others, which had moved about under the heavens, they found places and established their courses. It is said in the old sources that, from then on, times of day were differentiated and the course of years was set. So it is said in The Sibyl’s Prophecy:
Sun did not know
where she had her home.
Moon did not know
what strength he had.
The stars did not know
where their places were. (The Sibyl’s Prophecy. 5)
‘This was before the earth was created,’ Third added.
From The Prose Edda: Norse Mythology, trans. by Jesse Byock (Penguin, 2005), pp. 16-17.