Rauk

A rauk is a coastal rock formation, typically a limestone or dolostone pillar, stack, or arch that remains after ongoing erosion wears away the surrounding cliffs. The term is used in the Baltic and North Sea regions to describe these rugged, fossil-rich structures that punctuate shorelines.

Rauks form through long-term coastal erosion. Wave action concentrates at weaker, fractured, or softer layers, enlarging sea caves and undercutting the base of cliffs. Over time, arches can collapse, leaving isolated vertical remnants—the rauks. Changes in sea level and weathering can further modify their shapes, leading to stacks, islets, or detached towers.

Distribution and examples are most common along carbonate-rich coasts of northern Europe. Notable rauk landscapes occur along the southern Baltic coastlines and on islands such as Gotland, Öland, and parts of the Danish and German coasts. Some rauk fields are protected as natural monuments because of their geological importance and scenic value.

Significance and terminology: the rauk concept illustrates coastal erosion processes and the behavior of sedimentary rocks in temperate marine settings. In local languages, rauk refers specifically to these sea-stack and arch formations rather than to other rock types, and they are of interest to geologists, ecologists, and outdoor enthusiasts alike.