U1N1D2E1R1C3L1A1Y4
15 points
UNDERCLAY is validvalid
a stratum of clay lying beneath a coal bed, often containing the roots of coal plants
a stratum of clay lying beneath a coal bed, often containing the roots of coal plants
a stratum of clay lying beneath a coal bed, often containing the roots of coal plants
a stratum of clay lying beneath a coal bed, often containing the roots of coal plants