. "A geological unit is a volume of rock or ice of identifiable origin and age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it. Units must be mapable and distinct from one another, but the contact need not be particularly distinct. For instance, a unit may be defined by terms such as \"when the sandstone component exceeds 75% or more\"."@en . "Geological unit"@en . "A geological unit is a volume of rock or ice of identifiable origin and age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features (facies) that characterize it. Units must be mapable and distinct from one another, but the contact need not be particularly distinct. For instance, a unit may be defined by terms such as \"when the sandstone component exceeds 75% or more\"."@en . .