Stock Press Photo | Digerhuvud Naturreservat

The Gotland bedrock is largely made up of coral reefs that formed in a tropical sea about 430 million years ago, during the Silurian period. Between these fossil reefs are packs of stored limestone and muddy marl. After the last ice age, just over 10,000 years ago, Gotland was initially completely covered by water. Freed from the weight of the ice masses, however, the land eventually rose slowly above sea level. Where land and sea met, the waves could process the bedrock. The reef bodies themselves withstood the abrasion of the waves better than the surrounding stratified rocks, and when the water receded they could remain as isolated stone pillars - rauks. The Raukarna thus consist of hard, unstored limestone and are remnants of the ancient reefs that came to give rise to today's Gotland. Both the reef limestone and the stored limestone are rich in fossils of the many different kinds of animals that lived on and near the reefs: stromatoporoids, corals, snails, octopuses, mosses, armadillos and sea lilies.
Digerhuvud is located between Lauterhorn and Aursviken on Fårös northwest coast.

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