, also known as perched dunes
, are dunes
that occur on the tops of cliffs
. They are uncommon in most parts of the world, because they only develop under unusual geomorphological conditions. Processes by which they may be formed include:
- a dune advances up a pre-existing slope, which is then eroded to form a cliff;
- a dune forms during a period of high sea level, then sea level drops, exposing a cliff face.
They are most often seen as coastal landforms, but can also occur along lakes and rivers, and in deserts. Places where they are relatively common include the west coat of Jutland, Denmark.
- Saye, Samantha E., Kenneth Pye and Lars B. Clemmensen (2006). "Development of a cliff-top dune indicated by particle size and geochemical characteristics: Rubjerg Knude, Denmark". Sedimentology 53 1–21.