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Definition of graywacke in English:
graywacke
noun
(British greywacke)
Geology A dark coarse-grained sandstone containing more than 15 percent clay.
‘a 120-foot pyramid of battered graywacke a quarter mile offshore’- ‘the shales and graywackes of the Skiddaw Group’
- ‘The Southern Highland Group, consisting of greywacke, shale, limestone and volcanic rock, forms the top of the Dalradian succession.’
- ‘The rocks typically comprise a monotonous sequence of greywackes, reddish-weathering arkosic sandstones, shales and subordinate conglomerates.’
- ‘Higher vapour pressures would be generated in sediments of low permeability, such as mudstones, which would account for sills being more commonly found in shale and greywacke.’
- ‘Geologically the axes from the New Guinea Highlands comprise thermally metamorphosed basalt, chert and greywacke depending on quarry source.’
- ‘The builders used greywacke from the Rangitata River and limestone brought from Mount Somers and shaped the rocks by hand.’
Pronunciation
Origin
Late 18th century (as grauwacke): from German Grauwacke, from grau ‘gray’+ wacke. The anglicized form dates from the early 19th century.
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