How does a sand bar emerge?
Ølsemagle Sand Bar consists of decomposed material deposited by the sea through the ages in the inner part of Køge Bay. Due to currents and wind, the deposit took place some distance out in the bay – at first as a low reef under the surface of the sea and later as a sand bar. Such a reef is called a barrier island. In this way a lagoon emerged between the sand bars and the coast.
The shallow lagoon is the habitat of several species of plants and animals connected with saltwater and freshwater areas.