Blowouts are sandy
depressionDepression in geology is a landform sunken or depressed below the surrounding area. Depressions may be formed by various mechanisms, and may be referred to by a variety of technical terms.*A basin may be any large sediment filled depression...
s in a sand
duneIn physical geography, a dune is a hill of sand built by aeolian processes. Dunes are subject to different forms and sizes based on their interaction with the wind. Most kinds of dune are longer on the windward side where the sand is pushed up the dune, and a shorter "slip face" in the lee of the...
ecosystem (
psammosereA psammosere is a seral community, an ecological succession that began life on newly exposed coastal sand. Most common psammoseres are sand dune systems....
) caused by the removal of sediments by
windWind is the flow of air or other gases that compose an atmosphere . On Earth, wind consists of the bulk movement of air...
.
Blowouts occur in partially vegetated
duneIn physical geography, a dune is a hill of sand built by aeolian processes. Dunes are subject to different forms and sizes based on their interaction with the wind. Most kinds of dune are longer on the windward side where the sand is pushed up the dune, and a shorter "slip face" in the lee of the...
fields or
sandhillA sandhill is a type of ecological community or xeric wildfire-maintained ecosystem in the coastal plain of North America. It is not the same as a sand dune. It features very short fire return intervals, one to five years. Without fire, sandhills undergo ecological succession and become more oak...
s. A blowout forms when a patch of protective vegetation is lost, allowing strong winds to "blow out" sand and form a depression. Although they generally remain small, blowouts can expand to kilometers in size and up to around 70m in depth.
Causes of vegetation loss include extended droughts, fire (natural and anthropogenic) or, in extreme cases, trampling by humans, cattle, horses, etc.
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Blowouts are sandy
depressionDepression in geology is a landform sunken or depressed below the surrounding area. Depressions may be formed by various mechanisms, and may be referred to by a variety of technical terms.*A basin may be any large sediment filled depression...
s in a sand
duneIn physical geography, a dune is a hill of sand built by aeolian processes. Dunes are subject to different forms and sizes based on their interaction with the wind. Most kinds of dune are longer on the windward side where the sand is pushed up the dune, and a shorter "slip face" in the lee of the...
ecosystem (
psammosereA psammosere is a seral community, an ecological succession that began life on newly exposed coastal sand. Most common psammoseres are sand dune systems....
) caused by the removal of sediments by
windWind is the flow of air or other gases that compose an atmosphere . On Earth, wind consists of the bulk movement of air...
.
Blowouts occur in partially vegetated
duneIn physical geography, a dune is a hill of sand built by aeolian processes. Dunes are subject to different forms and sizes based on their interaction with the wind. Most kinds of dune are longer on the windward side where the sand is pushed up the dune, and a shorter "slip face" in the lee of the...
fields or
sandhillA sandhill is a type of ecological community or xeric wildfire-maintained ecosystem in the coastal plain of North America. It is not the same as a sand dune. It features very short fire return intervals, one to five years. Without fire, sandhills undergo ecological succession and become more oak...
s. A blowout forms when a patch of protective vegetation is lost, allowing strong winds to "blow out" sand and form a depression. Although they generally remain small, blowouts can expand to kilometers in size and up to around 70m in depth.
Causes of vegetation loss include extended droughts, fire (natural and anthropogenic) or, in extreme cases, trampling by humans, cattle, horses, etc. Fire is the most common cause, however. In time, succession will begin again as suitable seeds are blown in and pioneers become re-established.
Coastal sand dunes are found just inland from a beach, and are formed as the wind blows dry sand inland beyond the beach. It follows that this can only happen when there is an area of reasonably flat land inland from the beach. In time, this rather inhospitable surface will be colonised by pioneer species. These species (e.g. marram grass) will stabilise the dunes and prevent them moving any more. The process of
plant successionEcological succession, a fundamental concept in ecology, refers to the predictable and orderly changes in the composition or structure of an ecological community. Succession may be initiated either by formation of new, unoccupied habitat or by some form of disturbance of an existing community...
will eventually see these
duneIn physical geography, a dune is a hill of sand built by aeolian processes. Dunes are subject to different forms and sizes based on their interaction with the wind. Most kinds of dune are longer on the windward side where the sand is pushed up the dune, and a shorter "slip face" in the lee of the...
s converted to woodland (depending on the climate) and a mature soil will have formed.
Blowouts provide an important
habitatA habitat is an ecological or environmental area that is inhabited by a particular animal and plant species...
for flora and fauna.
See also
- Sand Hills (Nebraska)
The Sand Hills is a region of mixed-grass prairie on grass-stabilized sand dunes in north-central Nebraska, covering just over one quarter of the state. The region is variously defined by different organizations, so its size is indicated as 19,600 mi² or 23,600 mi² .-Geography:Dunes in the Sand...
- Blowout grass
Blowout grass is a grass that can be found on sand dunes. The plants grow in small clusters, protecting each other from the harsh desert conditions. The name of this grass may come from the word blowout which is when a slight depression in the ground and it turns into a bowl-shaped hollow...
- Sand dune ecology
Sand dune ecology describes the biological and physico-chemical interactions that are a characteristic of sand dunes.Sand dunes provide a range of habitats for a range of unusual, interesting and characteristic plants that can cope with disturbed habitats...
- Médanos
- Aeolian processes
- Yardang
A yardang is a wind-abraded ridge found in a desert environment. Yardangs are elongate features typically three or more times longer than they are wide, and when viewed from above, resemble the hull of a boat...
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