A wave-cut notch is formed by erosional processes such as abrasion and hydraulic action - this is a dent in the cliff usually at the level of high tide.The sea attacks the base of the cliff between the high and low water mark.A wave-cut platform is a wide gently-sloping surface found at the foot of a cliff.Ī wave-cut platform is formed when the following occurs: Soft rock erodes quickly and forms gentle sloping cliffs, whereas hard rock is more resistant and forms steep cliffs. Cliffs and wave-cut platformsĬliffs are shaped through erosion and weathering. Bays are more sheltered with constructive waves which deposit sediment to form a beach. Įrosional features such as wave-cut platforms and cliffs can be found on headlands, since they are more open to the waves. When the softer rock is eroded inwards, the hard rock sticks out into the sea, forming a headland. Hard rock such as chalk is more resistant to the processes of erosion. ![]() A bay is an inlet of the sea where the land curves inwards, usually with a beach. When a stretch of coastline is formed from different types of rock, headlands and bays can form.īands of soft rock such as clay and sand are weaker therefore they can be eroded quickly. Headlands and baysĬliffs along the coastline do not erode at the same pace. This stump usually forms a small rock island, low enough for a high tide to submerge.The process of erosion can create different landforms along the coastline. Eventually, erosion will cause the stack to collapse, leaving a stump. Further erosion causes the arch to collapse, leaving the pillar of hard rock standing away from the coast, the stack. If a cave wears through a headland, an arch forms. These cracks then gradually get larger and turn into caves. The formation process usually begins when the sea attacks lines of weakness, such as steep joints or small fault zones in a cliff face. (Cliffs with weaker rock, such as 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.) A more resistant layer may form a capstone. The medium hardness of these rocks means medium resistance to abrasive and attritive erosion. Stacks typically form in horizontally bedded sedimentary or volcanic rocks, particularly on limestone cliffs. Isolated steep-sided, rocky oceanic islets typically of volcanic origin, are also loosely called "stacks" or "volcanic stacks". ![]() Pizzomunno, a white limestone stack in Vieste, Italy Stacks can provide important nesting locations for seabirds, and many are popular for rock climbing. Erosion causes the arch to collapse, leaving the pillar of hard rock standing away from the coast-the stack. Without the constant presence of water, stacks also form when a natural arch collapses under gravity, due to sub-aerial processes like wind erosion. The force of the water weakens cracks in the headland, causing them to later collapse, forming free-standing stacks and even a small island. They are formed when part of a headland is eroded by hydraulic action, which is the force of the sea or water crashing against the rock. Stacks are formed over time by wind and water, processes of coastal geomorphology. The Duncansby Stacks at Duncansby Head, ScotlandĪ stack or sea stack is a geological landform consisting of a steep and often vertical column or columns of rock in the sea near a coast, formed by wave erosion.
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