Tombolo
A tombolo, from the Italian tombolo, derived from the Latin tumulus, meaning 'mound,' and sometimes translated as ayre (Old Norse eyrr, meaning 'gravel beach'), is a deposition landform in which an island is attached to the mainland by a narrow piece of land such as a spit or bar. Once attached, the island is then known as a tied island. Several islands tied together by bars which rise above the water level are called a tombolo cluster.[1] Two tombolos can form an enclosure (called a lagoon) that can eventually fill with sediment. Tombolos may be considered a type of isthmus.
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Morphology and sediment distribution
Tombolos are more prone to natural fluctuations of profile and area as a result of tidal and weather events than a normal beach is. Because of this susceptibility to weathering, tombolos are sometimes made more sturdy through the construction of roads or parking lots. The sediments that make up a tombolo are coarser towards the bottom and finer towards the surface. It is easy to see this pattern when the waves are destructive and wash away finer grained material at the top, revealing coarser sands and cobbles as the base. Sea level rise may also contribute to accretion, as material is pushed up with rising sea levels. This is the case with Chesil Beach (which connects the Isle of Portland to Dorset in England), notable because the shingle ridge is parallel rather than perpendicular to the coast.
Tombolos demonstrate the sensitivity of shorelines. A small piece of land, such as an island, can change the way that waves move, leading to different deposition of sediments.
List of notable tombolos
- The Angel Road of Shodo Island, Japan
- Aupouri Peninsula, New Zealand
- Ayre o Swinister, Shetland Islands, Scotland
- Barrenjoey Headland, Pittwater, New South Wales, Australia
- Beavertail Point, Conanicut Island, Rhode Island
- Biddeford Pool, Maine [2]
- Cádiz, Andalucía, Spain
- Chappaquiddick Island, Martha's Vineyard, Massachusetts
- Charles Island, Connecticut
- Chesil Beach, Dorset, England
- Cheung Chau, Hong Kong
- Fingal Bay, New South Wales, Australia
- The Rock of Gibraltar
- Grand Island National Recreation Area, Michigan, Lake Superior
- Gwadar, Pakistan
- Hakodate, Hokkaido, Japan
- Howth Head, Dublin, Ireland
- Inishkeel Island, Narin, Ireland
- The isthmus at Aden, Yemen
- Kapıdağ Peninsula, Balıkesir, Turkey
- Kettla Ness, Burra, Shetland Islands, Scotland
- Kurnell, Sydney, New South Wales, Australia
- Langness, Castletown Bay, Isle of Man
- Las Palmas de Gran Canaria, Canary Islands, Spain
- Llandudno, Wales
- Louds Island at Muscongus Bay, Maine
- Maharees, Dingle Peninsula, Ireland
- Mare Island, Vallejo, California
- Mersey Point, Shoalwater, Western Australia
- Miquelon, Saint-Pierre and Miquelon, France
- Monemvasia, Laconia, Peloponnese, Greece
- Monte Argentario, Tuscany, Italy
- Mount Maunganui, New Zealand
- Mount Taipingot, Rota, Northern Marianas
- Nahant, Massachusetts (a natural tombolo, but connected to the mainland by a causeway)
- Palisadoes, Kingston, Jamaica
- Presqu'ile Provincial Park, Ontario, Canada
- Presqu'ile de Giens, Hyères, France
- Quiberon, France
- Sainte-Marie, Martinique, France
- Sharp Island, Sai Kung, Hong Kong
- St Ninian's Isle, Shetland Islands, Scotland
- Scotts Head, Dominica
- Taylor's Island, Shelter Island, New York
- Yei of Huney, Huney, Shetland Islands, Scotland
- Nissi beach, Ayia Napa, Cyprus
See also
References
- ^ Glossary of Geology and Related Sciences. The American Geological Institute, 1957
- ^ Neal, William (2007). Atlantic Coast Beaches: A Guide to Ripples, Dunes, and Other Natural Features of the Seashore. Missoula, MT: Mountain Press Publishing Company. p. 272. ISBN 0-87842-534-9.
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External links
- Geology.About.com's page on tombolos (useful for its descriptive photograph)
