5-464: Stakkurin is the sea stack at the northernmost point of the island of Streymoy in the Faroe Islands . The owners of Stakkurin have sheep farming on top of the sea stack, and once a year they go out and bring back the sheep and sell them at an auction in the village Tjørnuvík . The money from auction goes to benefit the whole community, such as the community house. The sea stack can be reached by
10-406: A capstone . (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.) 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
15-409: A cable from Streymoy. Stack (geology) A 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 . Stacks are formed over time by wind and water, processes of coastal geomorphology. They are formed when part of a headland is eroded by hydraulic action , which is the force of
20-574: 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". Stacks typically form in horizontally bedded sedimentary or volcanic rocks , particularly on limestone cliffs. The medium hardness of these rocks means medium resistance to abrasive and attritive erosion . A more resistant layer may form
25-429: The sea or water crashing against the rock. The force of the water weakens cracks in the headland, causing them to later collapse, forming free-standing stacks and even a small island. Without the constant presence of water, stacks also form when a natural arch collapses under gravity , due to sub-aerial processes like wind erosion . Erosion causes the arch to collapse, leaving the pillar of hard rock standing away from
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