argil		clay. (and |argillaceous|, etc.)
gyttja		(geol.) an organic-rich mud found on the floor of certain lakes.
tephra		ash, cinder, and other fragmented volcanic ejecta.
malm		a soft limestone; a chalky soil of SE England; a mixture of chalk and clay for making bricks.
gangue		the earthy matrix in which a vein of ore is embedded.
bole		a red-brown color; soft clay used as a pigment.
drumlin		(geol.) a hill of glacial drift.
stade		the period of time represented by a glacial deposit.
edaphon		the fauna of the soil.