Gravel is a soil type described by Tom Stevenson (2011) as ‘a wide-ranging term that covers siliceous pebble of various sizes that are loose, granular, airy, and afford excellent drainage. Infertile, it encourages the vine to send its roots down deep in search of nutrients. Gravel beds above limestone subsoils produce wines with markedly more acidity than those above clay.’
Bibliography
Tom Stevenson (2011) The Sotheby’s Wine Encyclopedia 5th Edition by Tom Stevenson (Dorling Kindersley, 2011), p.17-19.