The fairy chimneys of the Massif des Ocres form large natural columns of friable sedimentary rocks with summits capped with rocks of a different nature and much more resistant to erosion. They originate from various erosion phenomena linked to the flow of rainwater and the chemical reactions between rocks and water, but also to the wind and the alternation of freezing and thawing periods. Their top caps protect the friable layers they shelter from erosion while the surrounding areas disappear over time.