The Fairy Chimneys are also called the Demoiselles Coiffées (Coiffed Ladies) because of the summit that seems to cap them like a hat and made of rock more resistant to the effects of erosion. They form natural columns of friable sedimentary rocks that can reach several tens of meters high. They have been eroded by the combined action of the rainwater flow and the chemical reactions between rocks and water, wind, and the succession of periods of freezing and thawing that destroy the rock by expansion.