Volcanic soils | A soil type described by Tom Stevenson (2011) as being ‘derived from two sources, volcanic soils are lava-based (the products of volcanic flow) and vent-based (material blown into the atmosphere). Some 90 per cent of lava-based rocks and soils are comprised of basalt, while others include andesite, pitchstone, rhyolite, and trachyte. Vent-based matter has either been ejected as molten globules, cooled in the air, and dropped to earth as solid particles (pumice), or as solid material and fractured through the explosive force with which it was flung (tuff).’
Tom Stevenson (2011) The Sotheby’s Wine Encyclopedia 5th Edition by Tom Stevenson (Dorling Kindersley, 2011), p.17-19.
John Szabo (MS), Volcanic Wines, (Jacqui Small, 2016).