"BGS Earth Material Classes"@en . . . "2011-02-10" . . . "http://data.bgs.ac.uk/ref/EarthMaterialClass"@en . . . . . "Types of material including single rock types, non earth materials and composite lithologies. This is an abstract schema that consists of 3 sub-schemas"@en . "Classifies all types of earth material or other substance that may be recorded in a geological log or section. This is an abstract schema that consists of 3 sub-schemas."@en . . .