Definition - What does Greywacke mean?
Greywacke is a type of soil with colored sedimentary sandstone that has been formed by river deposits mixed with rock fragments, quartz, compacted clay and feldspar.
This type of soils can be found in the vineyard regions of New Zealand, South Africa and Germany. It is a good soil for vineyards because of its rich mineral content and drainage capacity.
WineFrog explains Greywacke
Greywacke is a type of sandstone that has been categorized for its dark color, hardness and poorly sorted mix of quartz, lithic fragments and feldspar all set in clay. This is often found at the edges of continental shelves where strong turbidity currents or submarine avalanches have occurred.
The soil consists of compacted clay, which makes it an interesting soil for cultivating wine grapes. While most of the soil's mineral components and rocky fragments create a well-draining soil, the clay is able to hold a certain amount of water and moisture. This water reserve held within the clay can help sustain grape vines during the dry season, especially in regions where irrigation is not permitted.