What does wacke mean?
Wacke is a specialized geological term for a dark, clay-bearing sandstone. It consists chiefly of poorly sorted grains of quartz and feldspar together with angular fragments of other rocks, often including volcanic material. Because its components can vary considerably, wacke is commonly interpreted as the sedimentary record of rapid erosion and deposition in environments such as deep marine basins. The word occurs in geological descriptions of rock formations, sedimentary sequences, and sandstone textures, making it particularly relevant to geology, sedimentology, and petrography. Although it may sound like the informal adjective “wacky,” wacke is technical vocabulary rather than a humorous or colloquial term. It also overlaps historically with “greywacke,” a related designation for dark, clay-rich sandstone, but modern geological usage distinguishes the terms to some extent.
nounA dark, clay-bearing sandstone composed chiefly of poorly sorted grains of quartz, feldspar, and rock fragments. It is a specialized geological term for a type of sedimentary rock.
- A dark, poorly sorted, clay-bearing sandstone containing angular grains of quartz, feldspar, and other rock fragments.
"The cliff exposes a thick layer of wacke containing angular fragments of volcanic rock."
"The wacke sandstone was deposited rapidly in a deep marine basin."
"Petrographic analysis showed that the wacke contained fragments of granite, basalt, and quartz."
The plural is used when referring to multiple bodies or units of wacke.
"Distinct wackes from several basins contain different mixtures of mineral and rock fragments."
It sounds like “wacky,” but wacke is not a joke: it is the name of a dark, clay-rich sandstone used to read a region’s geological history.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of wacke
The English word was borrowed from German Wacke, a geological term continuing Middle High German wacke, which was associated with soft or loose stone. The English geological sense developed within the terminology of sedimentary petrology, while related forms such as wackestone preserve the same Germanic etymological base.
How wacke is actually used
This is a specialist term used mainly in geology, sedimentology, and petrography. Its historical definitions overlap with “greywacke,” although the terms are not always interchangeable in modern usage.
Easily confused with wacke
Wacke is a geological term for a clay-bearing sandstone, whereas wacky is an informal adjective meaning eccentric or unconventional.