Peninsula

The word peninsula derives from Latin paeninsula, from paene 'almost', and insula 'island'. The word entered English in the 16th century.^[3]

A peninsula is generally defined as a piece of land surrounded on most sides by water.^[5][9]

A peninsula may be bordered by more than one body of water, and the body of water does not have to be an ocean or a sea.^[10] A piece of land on a very tight river bend or one between two rivers is sometimes said to form a peninsula, for example in the New Barbadoes Neck in New Jersey, United States.^[5] A peninsula may be connected to the mainland via an isthmus, for example, in the Isthmus of Corinth which connects to the Peloponnese peninsula.^[11]

Peninsulas can be formed from continental drift, glacial erosion, glacial meltwater, glacial deposition, marine sediment, marine transgressions, volcanoes, divergent boundaries or river sedimentation.^[12] More than one factor may play into the formation of a peninsula. For example, in the case of Florida, continental drift, marine sediment, and marine transgressions were all contributing factors to its shape.^[13]

Glaciers

In the case of formation from glaciers (e.g., the Antarctic Peninsula or Cape Cod), peninsulas can be created due to glacial erosion, meltwater or deposition.^[14] If erosion formed the peninsula, softer and harder rocks were present, and since the glacier only erodes softer rock, it formed a basin.^[14] This may create peninsulas, and occurred for example in the Keweenaw Peninsula.^[14]

In the case of formation from meltwater, melting glaciers deposit sediment and form moraines, which act as dams for the meltwater.^[14] This may create bodies of water that surround the land, forming peninsulas.^[14]

If deposition formed the peninsula, the peninsula was composed of sedimentary rock, which was created from a large deposit of glacial drift.^[15][16] The hill of drift becomes a peninsula if the hill formed near water but was still connected to the mainland, for example during the formation of Cape Cod about 23,000 years ago.^[17][18]

Others

In the case of formation from volcanoes, when a volcano erupts magma near water, it may form a peninsula (e.g., the Alaskan Peninsula).^[15] Peninsulas formed from volcanoes are especially common when the volcano erupts near shallow water.^[19] Marine sediment may form peninsulas by the creation of limestone.^[20] A rift peninsula may form as a result of a divergent boundary in plate tectonics (e.g. the Arabian Peninsula),^[21][22] while a convergent boundary may also form peninsulas (e.g. Gibraltar or the Indian subcontinent).^[23] Peninsulas can also form due to sedimentation in rivers. When a river carrying sediment flows into an ocean, the sediment is deposited, forming a delta peninsula.^[24]

Marine transgressions (changes in sea level) may form peninsulas, but also may affect existing peninsulas. For example, the water level may change, which causes a peninsula to become an island during high water levels.^[25] Similarly, wet weather causing higher water levels make peninsulas appear smaller, while dry weather make them appear larger.^[26] Sea level rise from global warming will permanently reduce the size of some peninsulas over time.^[27]

Peninsulas are noted for their use as shelter for humans and Neanderthals.^[28] The landform is advantageous because it gives hunting access to both land and sea animals.^[28]They can also serve as markers of a nation's borders.^[29]

• Barrier island
• Cape
• Headland
• Promontory
• Salient
• Spit
• Tidal island

Bibliography

• The dictionary definition of peninsula at Wiktionary