Hard pan | A soil type described by Tom Stevenson (2011) as ‘a dense layer of clay that forms if the subsoil is more clayey than the topsoil at certain depths. As hard-pans are impermeable to both water and roots, they are not desirable too close to the surface but may provide an easily reachable water-table if located deep down. A sandy, iron-rich hard-pan known as iron-pan is commonly found in parts of Bordeaux.’


Tom Stevenson (2011) The Sotheby’s Wine Encyclopedia 5th Edition by Tom Stevenson (Dorling Kindersley, 2011), p.17-19.