The Oligocene of the Prebetic in the Jumilla-Yecla area is mainly represented by fluvial and alluvial sediments. The elementary sequence observed in these materials is made up by conglomerates, sandstones and marlstones. Intercalated in this sequence continental carbonates appear. These carbonates are characterized by the presence of rhizoliths, laminar calcretes, glaebular or nodular textures and Microcodium. These carbonates are interpreted as calcretes and their features show the great importance of the vegetation in the pedogenic origin. Then, they could be the consequence of a warm to hot climates and low, seasonal rainfall conditions