Tied island

View from the Isle of Portland looking towards the mainland of Great Britain. Chesil Beach on the left connects the tied island to the mainland.

St. Ninian's Isle, a tied island during all but the very highest tides

Tied islands, or land-tied islands as they are often known, are landforms consisting of an island that is connected to land only by a tombolo: a spit of beach materials connected to land at both ends. St. Ninian's Isle, in the Shetland Islands off the north coast of Scotland, is an example of this; it was once an island but is now linked to the mainland. Other examples include: Coronado, California and Nahant, Massachusetts in the U.S.; Barrenjoey, New South Wales in Australia; and Wedge Island in Western Australia.

The Isle of Portland is also referred to as a tied island, although geographers now believe that Chesil Beach (which connects the island to the mainland) is a barrier beach which has moved eastwards, rather than a tombolo, which would have been formed by the effect of the island on waves.

References

• Glossary of geology and related sciences. Jesse V. Howell, American Geological Institute. 1962.
• Some Coastal Landform Definitions. Matthew Flinders, Villanova College, Queensland.

External links

• Media related to Tied islands at Wikimedia Commons

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