They also protect the berm from erosion by high winds, freak waves and subsiding floodwaters. The contractions may persist for many weeks before gradually subsiding. Many thousands of feet of sediment filled the slowly subsiding basin. Seawater trapped in the subsiding basin created thick evaporite deposits by Mid Pennsylvanian. Currently the island is subsiding, and Montagna Grande is slowly sinking. The pain and fever last for about a day before rapidly and completely subsiding. In addition, the land on which it is built is slowly subsiding. The Sudd swamps which form the central part of the basin may still be subsiding. Localised right-lateral slip of was observed at the subsiding west side of the rupture. This is due to the subsiding of coastal lands. Piled foundations were necessary to prevent the station subsiding. The valley is subsiding due to the removal of ground water. With revolution subsiding, Metternich was hopeful they would return to Vienna. By the mid-19th century the bridge was subsiding badly and expensive to maintain. The term for the subsiding or cessation of an erection is "detumescence".