The slopes of Castellet and Brulat rest on a relatively homogeneous geological substratum made up of marls and limestones.
The heart of the estate, located on a plateau 150 metres above sea level, dating from the Santonian period, is made up of decalcified terra rossa-type clay, sandstone, very often pebbly, and marly, sandy and silty white soil.
The formidable geological reserve that is the hill is evidence of a overthrust zone that is probably 20 million years old (rocks originating from the La Cadière and Gros Cerveau reefs containing bivalve fossils, or rudists).
Ref : J.J Chateauneuf (30 juillet et 5 août 1997)