seaisland

A seaisland, also known as a sea stack, is a geological formation consisting of a steep, often vertical rock column that rises from the sea. These features are typically found along coastlines and are formed by erosion. The process begins with a headland or promontory made of more resistant rock. Waves, driven by the force of the sea, repeatedly strike the base of this headland. Over time, this constant battering carves out a cave. As erosion continues, the cave may deepen and widen, eventually penetrating through the headland to form an arch.

Eventually, the arch can no longer support its own weight and collapses, leaving behind a detached column of rock. This isolated pillar is the seaisland. The process of seaisland formation is a continuous cycle of erosion. The seaisland itself will continue to be weathered by the sea and the elements, and will eventually erode away, becoming smaller and flatter until it is no more than a submerged rock or a small reef. Seaislands are a striking visual testament to the power of coastal erosion and the dynamic nature of shorelines. They often become important habitats for seabirds, which nest on their steep cliffs, and can be distinctive landmarks in marine landscapes.