Item talk:Q161322
From geokb
Geoscience Ontology Description
Sediment consisting of less than 30 percent gravel-size (2 mm) particles and with a mud-size to sand-size particle ratio greater than 1. Clasts may be of any composition or origin. BGS (Hallsworth and Knox, 1999, p. 9) define the 'upper size limit of mud ... at 32 micrometers (.032 mm)', but Wentworth scale and Krumbein scale put boundary at .064 or .062 mm (inidistinguishable difference in rocks...) BGS 'mud-grade sediment' or sedimentary rock definition is 'over 75% of the clasts smaller than .032 mm', which is narrower than the definition here.
