Ur (continent)

Ur was a supercontinent that formed 3,000 million years ago (3 billion) in the early Archean eon;^[1] perhaps the oldest continent on Earth, half a billion years older than Arctica, but it may have been preceded by one other supercontinent, Vaalbara, which is suggested to have formed about 3,600 to 3,100 million years ago.^[2]

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.^[3]

Formation and breakup

Rocks that made up Ur are now parts of Africa, Australia, and India.^[3]

In the early period of Ur's existence, it was probably the only continent on Earth, and as such is considered a supercontinent, though it was probably smaller than present-day Australia.

When Ur was the only continent on Earth, all other land was in the form of small granite islands and small land-masses like Kenorland that were not large enough to be continents.

Timeline

All dates below are approximate.

• 3 billion years ago, Ur formed as the only continent on Earth.
• 2.8 billion years ago, Ur was a part of the major supercontinent Kenorland.
• 2 billion years ago, Ur was a part of the major supercontinent Columbia.
• 1 billion years ago, Ur was a part of the major supercontinent Rodinia.
• 550 million years ago, Ur was a part of the major supercontinent Pannotia.
• 300 million years ago, Ur was a part of the major supercontinent Pangaea.
• 208 million years ago, Ur was torn apart into parts of Laurasia and Gondwana.
• 65 million years ago, the African part of Ur was torn apart as part of India.
• Present, Ur is part of Australia and Madagascar.

Notes

• Lerner, K. Lee; Lerner, Brenda Wilmoth, eds. (2003). "Supercontinents". Gale Cengage/eNotes.com. 
• Zubritsky, Elizabeth (1997). "In the beginning, there was Ur". Endeavors. 

References

External links

• Discover article