noun[mass noun] Geology
A sandstone of which the mud matrix in which the grains are embedded amounts to between 15 and 75 per cent of the mass.
More example sentences
- The rounded conglomerate pebbles consist of siltstone, mudstone, wacke, granophyric igneous rocks, and various intermediate to felsic volcanic rocks, set in a matrix rich in quartz and feldspar grains.
- The Annascaul Formation is at least 500 m thick, and is dominated by mudrocks with subordinate quartz wacke sandstones, tuffaceous fine conglomerates and melange.
- The upper 300 m of the Haengefjeldet Formation is made up of 3-10 m thick well-sorted, normally graded, matrix-supported sandstones and wackes.
early 19th century: from German, from Middle High German wacke 'large stone', Old High German wacko 'pebble'.
Definition of wacke in:
- The US English dictionary