Greywacke is a soil type (pronounced ‘graywacky’) ‘found throughout much of New Zealand consisting of grey sandstone with a high clay content and plenty of coarse-grained particles giving stony, free-draining soils,’ (Julia Harding MW, jancisrobinson.com 24 Jan 2014). Tom Stevenson defines Greywacke as ‘argillaceous rocks that could have been formed as recently as a few thousand years ago by rivers depositing mudstone, quartz, and feldspar. Commonly found in Germany, South Africa, and New Zealand.’

Bibliography

Tom Stevenson (2011) The Sotheby’s Wine Encyclopedia 5th Edition by Tom Stevenson (Dorling Kindersley, 2011), p.18.