Cliff-top dunes, also known as perched dunes, are
dune
A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat ...
s that occur on the tops of
cliff
In geography and geology, a cliff or rock face is an area of Rock (geology), rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. ...
s. 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 coast of
Jutland
Jutland (; , ''Jyske Halvø'' or ''Cimbriske Halvø''; , ''Kimbrische Halbinsel'' or ''Jütische Halbinsel'') is a peninsula of Northern Europe that forms the continental portion of Denmark and part of northern Germany (Schleswig-Holstein). It ...
,
Denmark
Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...
. They can also be found in certain places along the shores of the
Great Lakes
The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes spanning the Canada–United States border. The five lakes are Lake Superior, Superior, Lake Michigan, Michigan, Lake Huron, H ...
in
Michigan
Michigan ( ) is a peninsular U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, Upper Midwestern United States. It shares water and land boundaries with Minnesota to the northwest, Wisconsin to the west, ...
, including the Grand Sable Dunes in
Pictured Rocks National Lakeshore
Pictured Rocks National Lakeshore is a U.S. National Lakeshore in the Upper Peninsula of Michigan, Upper Peninsula of Michigan, United States. It extends for along the shore of Lake Superior and covers . The park has extensive views of the h ...
and in the
Sleeping Bear Dunes National Lakeshore, most dramatically on
South Manitou Island.
References
*
{{coastal geography
Coastal geography
Coastal and oceanic landforms
Dunes