Boulbènes | A soil type found on the right bank of the Bordeaux region, in the Premières Côtes and Entre Deux Mers. Boulbènes is a very fine, siliceous, compacted silt which is hard to work, and a barrier for all but the most determined vine roots. Tom Stevenson (2011, p.18) describes boulbènes as the ‘Bordelais name for a very fine siliceous soil that is easily compressed and hard to work. This “beaten” earth covers part of the Entre-Deux-Mers plateau.’
Tom Stevenson (2011) The Sotheby’s Wine Encyclopedia 5th Edition by Tom Stevenson (Dorling Kindersley, 2011), p.18.