Erosional Features Flashcards
What is a blowhole and how is one formed?
What: Blowholes occur as sea caves along the shore can have an opening in the ground above. When waves enter the sea cave with sufficient force, water can travel upward with great pressure and escape through the opening.
Formation: Sea caves can grow when exposed to wave action. Sometimes a portion of the cave can grow upward until it creates an opening in the ground above. Lava flows can also create openings in the ground that extend seaward.
How is a cave formed?
Caves occur when waves force their way into cracks in the cliff face. The water contains sand and other materials that grind away at the rock until the cracks become a cave. Hydraulic action is the predominant process.
How is an arch formed?
If a cave is formed in a headland, it may eventually break through to the other side forming an arch.
How is a stack formed?
An arch will gradually become bigger until it can no longer support the top of the arch. When the arch collapses, it leaves the headland on one side and a stack (a tall column of rock) on the other.
How is a stump formed?
A stack will be attacked at the base in the same way that a wave-cut notch is formed. This weakens the structure and it will eventually collapse to form a stump.
How is a wave-cut platform formed?
When a wave-cut notch is formed at the base of a cliff from erosion, a “cave” is formed and eventually the cave will become deep enough that the cliff cannot be supported and collapses; a wave cut platform is the result.
What wave type causes erosion and thus erosional features?
Destructive waves.
What is a destructive wave?
They occur when wave energy is high (such as in storms) and the wave has travelled over a long fetch. They tend to erode the coast. They have a stronger backwash than swash.
What is a wave-cut notch?
A wave-cut notch is formed when sea waves undercut the base of a cliff. It is simply just an indent bat the cliff foot.
