Sand Beaches, Isles and Dunes|
Off the East Friesian coast there is a belt of 7 larger inhabited and of some smaller and unoccupied dune islands. They - as well as the West Friesian islands off the Dutch coast - originated from a sand wall which was broken through. The North Friesian islands, on the other hand, are remnants of the former mainland, which was broken off during several storm catastrophes in the Middle Ages.
Together with sandbanks and reefs, the dune islands form a barrier system which moderates storm tides, currents and tidal waves. Thereby, they have made a contribution to the formation and protection of the mud flats and the salt meadows.
The area of sand beaches extends from the line of low water to the foot of the dunes or the dike.
The water movement and the wind allow only bigger particles to be deposited but they can be moved at any time. If there are heavy storms (mostly from the Northwest), it happens that the wet shore (it is found between the lines of low and high water) gets carried away. On the dry shore the wind carries the dry sand masses to the dunes.
Because of these conditions, there won't be found any larger accumulation of higher plants.
In contrast to the mud flats, no larger animals live in sub-terranean burrows on the sand beaches. But several hundred species of tiny animals live here. Most of them are not bigger than a grain of sand.
Sand and Sea Plovers as well as Ferns generally breed on the sand beach. Their clutches of eggs lie open and unprotected on the ground, but they are very well camouflaged because of the eggs' color and markings.
At the edge of the sea many birds search for food. They live on small animals, which live in the organic material washed ashore by the sea.
Moving inland, several lines of dunes border on the sand beach. As a matter of fact, the oldest dunes are found furthest inland, while the young dunes face the sea.
The formation of the dunes is a very complicated process, for which the interplay of water, wind and vegetation is of fundamental importance. In the coastal area of Lower Saxony, dunes can only be found on the offshore islands. Therefore, the formation of dunes is also part of the genesis of the isles.
If sand masses are being deposited up to height that is above the level of the average high water, the sand isn't eroded regularly any longer. The upper sand layers get carried away with the wind and are deposited again behind small obstacles, sea shells and flotsam, for instance. This process mainly takes place on the windward side of sandbanks and sand beaches.
Although the nutritional value of this sand is relatively high, only a few salt-resisting plants grow here. These small accumulations of plants are of great importance for the further dune-formation. These plants have their roots in the sand. Thus, on the one hand the erosion of sand is made nearly impossible, and on the other hand its sedimentation increases. The more sand is deposited and the more vegetation is established, the higher the dunes grow.