marl /mɑrl/

1. Geology. a friable earthy deposit consisting of clay and calcium carbonate, used esp. as a fertilizer for soils deficient in lime.
2. Archaic. earth.
(used with object)
3. to fertilize with marl.

[Origin: 1325-75; ME marle < MD < OF < ML margila, dim. of L marga, said to be < Gaulish]

-Related forms
/mɑrˈleɪʃəs/, marly, adjective