The ochres of the Provençal Colorado of Rustrel tell the geological history of the region. Back when Provence was covered by water, marine sediments accumulated over successive deposits of white limestone, gray clays, and green sands loaded with glauconia (marine clay rich in iron). Tectonic movements later participated in the emergence of Provence. The torrential rains of the tropical climate of the time altered the green sands into ocher and white sands while kaolinites (alumina silicates) crystallized. The ochers of Luberon owe their pigmentation and remarkable color palette to goethite (iron oxy-hydroxides), limonite (iron hydroxide), and hematite (iron oxides).