The sons of Borr slay Ymir and shape the world from his body: the flesh became earth, the blood became sea, the bones became mountains, and the skull became the vault of the sky.

Þeir Óðinn ok Vili ok Vé lögðu Ymi niðr ok drápu hann. En er hann fell, þá hljóp svá mikit blóð ór sárum hans at með því drukknuðu allir hrímþursar, nema einn komsk undan með sina hyski.

Odin and Vili and Ve laid Ymir down and slew him. When he fell, so much blood poured from his wounds that all the frost-giants drowned in it, save one who escaped with his household.

Þeir tóku Ymi ok fluttu í miðgarð Ginnungagaps ok gerðu af honum jörðina: af blóði hans sæinn ok vötnin, af holdinu jörðina, af beinum björgin, grjót ok urðir gerðu þeir af tönnum ok jaxli ok af þeim beinum er brotna höfðu. Af hausnum gerðu þeir himininn.

They took Ymir and carried him to the middle of Ginnungagap and made of him the earth: of his blood the sea and the waters, of his flesh the earth, of his bones the mountains; stones and boulders they made of his teeth and jaws and the bones that had been shattered. Of his skull they made the sky.

Eddic quotations

Grímnismál 40-41

Ór Ymis holdi var jörð um skapat, en ór sveita sær, björg ór beinum, baðmr ór hári, en ór hausi himinn.

From Ymir's flesh the earth was shaped, and from his blood the sea, the mountains from his bones, the trees from his hair, and from his skull the sky.