Blowouts in sand dunes are hollows or depressions created by wind erosion within existing sand deposits, often associated with accompanying sand accumulations.
Understanding Sand Dune Blowouts
According to research (Glenn 1979; Hesp 2002), a blowout is a depression or hollow formed by wind erosion on a preexisting sand deposit. They are not isolated features but are formed together with an adjoining sand accumulation such as a depositional lobe, a blowout dune, or a garmada. The sand that forms these adjoining accumulations is primarily derived from the blowout depression itself, although it can also come from other sources.
How Blowouts Form
Blowouts occur when strong winds erode sand from a weak spot on a dune or sand sheet. This often happens where vegetation cover is sparse or disturbed, exposing the underlying sand. The wind then scoops out a hollow, transporting the sand downwind to form a mound or ridge.
- Initiation: Weak points in vegetation or surface crusts.
- Erosion: Wind removes sand, creating a depression.
- Deposition: Sand carried by the wind accumulates downwind.
Key Components of a Blowout System
A blowout isn't just the hollow; it's a system comprising both the eroded area and the deposited sand.
| Component | Description |
|---|---|
| Blowout (Depression) | The hollow or scooped-out area formed by wind erosion. |
| Adjoining Accumulation | Sand deposited downwind from the blowout. Can be a lobe, dune, or garmada. |
| Sand Source | Primarily the blowout depression, but can include surrounding sand. |
This dynamic process of erosion and deposition shapes the landscape in many sand dune environments.
