The Sainte-Barbe Clays Formation is a geological formation in Belgium. It is found in localised areas of the northern margin of the Mons Basin, alongside the equivalently aged Hautrage and Baudour Clay Formations. It is Upper Barremian-Lower Aptian in age. It predominantly consists of laminated clay, with some lignite. It is well known for the "Iguanodon sinkhole" locality near Bernissart where many specimens of Iguanodon bernissartensis were described by Louis Dollo in the late 19th century.
The Sainte-Barbe Clays Formation are part of the stratigraphy of the Mons Basin, a Cretaceous-Cenozoic sedimentary basin in western Belgium. The subsidence of the basin floor is caused by the dissolution of anhydrite in the Carboniferous basement. Wealden facies are the oldest units within the basin, and are only found on the northern margin of the basin, being absent from the central and southern parts of the basin. Localised areas of significant subsidence, referred to as "sinkholes" are observed. The Wealden facies are overlain by "mixed siliciclasticâÂÂcarbonate formations" called Meules dating to the Albian.
The Tettigarctid cicada Hylaeoneura lignei is known from the formation.