|Elevation||70 metres (230 ft) (as an island)
Below sea level (present)
|Prominence||Below sea level|
|Location||The Atlantic Ocean's sea floor southwest of Surtsey, Iceland|
|Age of rock||Unknown|
Jólnir was formerly a volcanic island south of Iceland. It was a former vent of Surtsey, along with Syrtlingur and Surtla. It emerged from the ocean as a result of active plate tectonics in July, 1966. Oceanic erosion cyclically wore down the new land as it formed, and the island sank below the surface several times.
Jolnir's formation is closely linked to that of neighboring volcanic island, Surtsey, which emerged in 1963. Volcanic eruptions occurred in much of the surrounding water, but newly formed land was subject to oceanic erosion and many small islands washed away. By 1966, Jólnir had broken the surface, and the changing composition of the emerging material resulted in harder rock forms resistant to erosion. The volcanic cone reached 70 meters above sea level, but even this landmass eventually gave way to the eroding ocean waves.
After activity ceased on 8 August 1966, the Atlantic Ocean's waves was rapidly weathering the volcanic island. During October 1966, the island disappeared below the Atlantic Ocean's surface after 3 months of being weathered by ocean water.
- Photograph and brief description from United States Armed Forces newspaper Stars and Stripes.
- Another photograph of Jolnir in 1966
- University of North Dakota page about Surtsey and Jolnir
- Brief description from Dartmouth, at the bottom.
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