出典:Wiktionary
ur-continent (複数形 ur-continents)
出典:Wikipedia
出典:『Wikipedia』 (2011/03/15 12:40 UTC 版)
Ur was a supercontinent that formed 3,000 million years ago (3 billion) in the early Archean eon; the oldest continent on Earth, half a billion years older than Arctica. Ur joined with the continents Nena and Atlantica about 1,000 million years ago (1 billion) to form the supercontinent Rodinia. Ur survived as a single unit until it was sundered when the supercontinent Pangaea broke apart into Laurasia and Gondwana.