Dune island
A dune island was created by sand deposits in shallow water ( sand bank ). If the water currents are so calm at this point that more sand is washed up than washed away and the sandbank protrudes out of the water not only at low tide ( high sand ), the wind can pile up a dune on which birds breed. The colonization by plants consolidates the dunes and increases them. Just like dunes on land, the dunes of a dune island migrate and thus greatly change the size, but also the location and shape of the island.
Islands that were created by dunes are, for example, the West and East Frisian Islands .
Uninhabited dune islands off the German coast:
- Trischen , probably first vegetation around 1700, shrunk to high sand again by 1750, renewed vegetation from 1850, from 1900 to 1947 unsuccessful attempt at human use, since then a nature reserve. The island "migrates" about 30 to 35 meters towards the coast every year.
- On Scharhörn , the first breeding birds were observed in 1902, and the first vegetation in 1926, after which considerable effort was made to plant and sow the sand traps.
- The neighboring Ni-Horn was created by the erosion of sand in 1989/90, so it is not a real dune island.
- The Kachelotplate has stood out since 1975 even at medium floods, but the dunes that were created were leveled again during storm surges .
Other: The island of Sable Island off the Canadian coast in the Atlantic was created either by the shifting of sand by glaciers during the last ice age or by a dune island.