Tied islands, or land-tied islands, as they are often known, are a landform where the island is only connected to land by a tombolo

Tombolo

A tombolo, from the Italian tombolo, derived from the Latin tumulus, meaning 'mound,' and sometimes translated as ayre , 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...

—a spit

Spit (landform)

A spit or sandspit is a deposition landform found off coasts. At one end, spits connect to land, and extend into the sea. A spit is a type of bar or beach that develops where a re-entrant occurs, such as at cove's headlands, by the process of longshore drift...

 of beach materials connected to land at both ends. The Isle of Portland

Isle of Portland

The Isle of Portland is a limestone tied island, long by wide, in the English Channel. Portland is south of the resort of Weymouth, forming the southernmost point of the county of Dorset, England. A tombolo over which runs the A354 road connects it to Chesil Beach and the mainland. Portland and...

 on the south coast of England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 is an example of this; it was once an island but is now linked to the mainland by Chesil Beach

Chesil Beach

Chesil Beach, sometimes called Chesil Bank, in Dorset, southern England is one of three major shingle structures in Britain. Its toponym is derived from the Old English ceosel or cisel, meaning "gravel" or "shingle"....

. Other examples include St. Ninian's Isle, Shetland; North Island

Naval Air Station North Island

Naval Air Station North Island or NAS North Island is located at the north end of the Coronado peninsula on San Diego Bay and is the home port of several aircraft carriers of the United States Navy...

, San Diego, California

San Diego, California

San Diego is the eighth-largest city in the United States and second-largest city in California. The city is located on the coast of the Pacific Ocean in Southern California, immediately adjacent to the Mexican border. The birthplace of California, San Diego is known for its mild year-round...

; and Barrenjoey, New South Wales

Barrenjoey, New South Wales

Barrenjoey is a locality in the suburb of Palm Beach, at the farthest northern tip of Pittwater. The headland is mostly made up of Hawkesbury sandstone which overlays Narrabeen shale. Around 10,000 years ago the headland was cutoff from the mainland due to the rising sea level; subsequent buildup...

 in Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

.