Stack (geology)
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Victoria, Australia
A stack or sea stack is a
wind erosion. Erosion causes the arch to collapse, leaving the pillar of hard rock standing away from the coast—the stack. Eventually, erosion will cause the stack to collapse, leaving a stump. Stacks can provide important nesting locations for seabirds, and many are popular for rock climbing
.
Isolated steep-sided, rocky oceanic
islets
typically of volcanic origin, are also loosely called "stacks" or "volcanic stacks".
Formation
Stacks typically form in horizontally bedded
claystone or highly jointed rock, tend to slump and erode too quickly to form stacks, while harder rocks such as granite erode in different ways.)[4]
The formation process usually begins when the sea attacks lines of weakness, such as steep joints or small fault zones in a cliff face. These cracks then gradually get larger and turn into caves. If a cave wears through a headland, an arch forms. Further erosion causes the arch to collapse, leaving the pillar of hard rock standing away from the coast, the stack. Eventually, erosion will cause the stack to collapse, leaving a stump. This stump usually forms a small rock island, low enough for a high tide to submerge.
See also
- Ball's Pyramid, the tallest sea stack in the world
- List of sea stacks
- Rauk
References
- ISBN 0-13-860958-6.
- ^ "Sea stacks" britannica.com Archived 2009-04-14 at the Wayback Machine
- ^ "Mayo - County Geological Site Report" (PDF). Geoheritage. Geological Survey of Ireland. Retrieved 28 December 2023.
- ISBN 9781402038808.
External links
Media related to Geological stacks (category) at Wikimedia Commons
