A peninsula is generally defined as a piece of land surrounded on most sides by water.[8][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 theNew Barbadoes Neck inNew Jersey, United States.[8] A peninsula may be connected to the mainland via anisthmus, for example, in theIsthmus of Corinth which connects to thePeloponnese peninsula.[11]
Peninsulas can also be man-made. Typically, they are built as protection from ocean or sea waves by building aBreakwater, which sometimes connects back to land. They can also be built to expand areas of a city; for example,Copenhagen is planning to create a peninsula that houses 35,000 residents by 2070.[14]
In the case of formation from glaciers (e.g., theAntarctic Peninsula orCape Cod), peninsulas can be created due to glacialerosion,meltwater ordeposition.[15] If erosion formed the peninsula, softer and harder rocks were present, and since the glacier only erodes softer rock, it formed abasin.[15] This may create peninsulas, and occurred for example in theKeweenaw Peninsula.[15]
In the case of formation from meltwater, melting glaciers deposit sediment and formmoraines, which act as dams for the meltwater.[15] This may create bodies of water that surround the land, forming peninsulas.[15]
If deposition formed the peninsula, the peninsula was composed ofsedimentary rock, which was created from a large deposit ofglacial drift.[16][17] 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.[18][19]
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.[26] Similarly, wet weather causing higher water levels make peninsulas appear smaller, whiledry weather make them appear larger.[27]Sea level rise from global warming will permanently reduce the size of some peninsulas over time.[28]
Peninsulas are noted for their use as shelter for humans andNeanderthals.[29] The landform is advantageous because it gives hunting access to both land and sea animals.[29] They can also serve as markers of a nation's borders.[30] In history, Peninsulas have played vital role in trade and commerce because of their access to water through an isthmus. The Malay Peninsula, located at the convergence of the Indian Ocean and the Chinese Seas, played an important role in east-west trade.[31]
