Coastal and Oceanic Landform (27.Island)

                                                                                                                         Back to Coastal and Oceanic Landform

  • An island is any piece of sub-continental land.
  • That is surrounded by water.
  • Very small islands emergent land features on atolls can be called;
  • An island in a river or an island in a lake may be called an eyot/ holm.
  • A grouping of geographically or geologically related islands is called an archipelago.
  • An island may still be described artificial land bridge.

       example ;Singapore, causeway
                         Dutchdelta islands

  • Historical reasons being connected to a larger landmass by a wide land bridge, such as Coney Island.
  • Piece of land is separated from the mainland by a man-made canal;
                         example-: Peloponnese by the Corinth Canal, it is not considered an island.

  • Main types of islands: 
                        1.Continental islands
                        2.Oceanic islands

  • Greenland is the world's largest island.
  • Australia the world's smallest continent.

Difference between islands and continents 
  • Continental lithosphere is part of tectonic plates floating high on Earth's molten mantle. 
  • Oceanic crust is also part of tectonic plates.
  • It is denser than continental lithosphere.
  • It floats low on the mantle.
  • Islands extensions of the oceanic crust.
  • They are part of some continental lithosphere.
                                                     e.g. Greenland

Continental islands 
  • Bodies of land.
  •  That lie on the continental shelf of a continent.
  • A microcontinental island is special continental island.

 Examples-: Greenland
                                                                                                                       Long Island
                          Sable Island    
                          Trinidad off South America
                                                                                                                      Great Britain
                                                                                                                      Sicily off Europe
                         Java off Asia
                                                                                                                        New Guinea
                                                                                                                         Kangaroo Island off Australia

Oceanic islands 
  • Do not sit on continental shelves.
  • The vast majority are volcanic in origin.
Examples;  Saint Peter and Paul Rocks
                        Macquarie Island in the Pacific

1.volcanic island arc-
Hawain island
Hawain island
  • Subduction of one plate under another is occurring.
                  Examples ;Mariana Islands
                                        Aleutian Islands
                                        Tonga in the Pacific Ocean
                                        South Sandwich Islands

2.Oceanic rift -
  • Reaches the surface.
                           examples: Iceland
                                                Jan Mayen 

3.Volcanic hotspots-
  •  A hotspot is more or less stationary relative to the moving tectonic plate above it.
  • A chain of islands results as the plate drifts.
  •  Over long periods of time, this type of island is eventually "drowned" by isostatic adjustment and eroded, becoming a seamount.
  • Plate movement across a hot-spot produces a line of islands oriented in the direction of the plate movement.
                                 example ;Hawaiian Islands
                                                    Tuamotu Archipelago

An atoll

  • Formed from a coral reef.
  • Grown on an eroded & submerged volcanic island.
  • The reef rises to the surface of the water and forms a new island.
  • Atolls are typically ring-shaped with a central lagoon.
                                  Examples ;Maldives
                                                         Line Islands

Tropical islands
  • There are approximately 45,000  on Earth.
  • Coral tropic islands are; 

Granite islands
  • Include Seychelles and Tioman.
  • The socio-economic ranges from the Stone Age societies ,in the interior of ;
                                       Borneo or Papua New Guinea 

  • The high-tech lifestyles of the city-islands of ;
                                      Hong Kong

  • International tourism is a significant factor in the local economy ;

Galicia Island
Galicia Island

 Desert island 
  • Island with no people.
  • Exists in a state of being deserted, or abandoned.
  • An ariddesert climate is not typically implied.

Natural and artificial  island
  • Earth's islands are natural.
  • Formed by tectonic forces or volcanic eruptions.
  • Artificial or man-made islands also have  our earth.
                                      example ;Osaka Bay off the Japanese island of Honshu,

  • Artificial islands can be built using natural & artificial materials.
                             e.g. dirt

                                   recycled waste
                                  concrete slabs)

  • Sometimes natural islands are  enlarged.
                      example ; Vasilyevsky Island 

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