Peninsula

Peninsulas can exist in multiple forms and situations. 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] If a peninsula is located in an inland body of water (lake, river) it is also referred to as an "inland peninsula".

There is no precise definition distinguishing peninsulas from less prominent extensions, and extensions conventionally considered peninsulas are not always named as such; they can also be referred to as a headland, cape, island promontory, bill, point, fork, or spit.[12] A point is generally considered a piece of land projecting into a body of water that is less prominent than a cape.[13]A form of the peninsula is the headland and the particularly narrow spit that has been washed up.[14][15]

Multiple natural factors can play a part in the formation of peninsulas. For example, in the case of Florida, continental drift, sedimentation, and marine transgressions were all contributing factors to its shape.[16] Some peninsulas may also be formed from glaciers or volcanoes.[17] In the case of formation from glaciers, (e.g. the Antarctic Peninsula or Cape Cod) the sedimentary rock comprising the peninsula was deposited from glaciers or streams.[18] It becomes a peninsula if a hill of till formed near water but still connects to the mainland, for example during the formation of Cape Cod about 23,000 years ago.[19] In the case of formation from volcanoes, if a volcano is erupting magma near water, it may form a peninsula (e.g. the Alaskan Peninsula).[18]

A rift peninsula may form as a result of a divergent boundary in plate tectonics (e.g. the Arabian Peninsula).[20] 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.[21]

Marine transgressions (changes in sea level) may form peninsulas, but also may affect existing peninsulas. For example, the water level may variate, which causes a peninsula to become an island during high water levels.[22] Similarly, wet weather causing higher water levels can make peninsulas appear smaller, while dry weather can make them appear larger.[23] Sea level rise from global warming may permanently reduce the size of peninsulas over time.[24]

• Barrier peninsula
• Isthmus