Emily Dickinson Lexicon

MARL, n. [W. marl; D. Sw. Dan. and G. mergel; L. Sp. and It. marga; Ir. marla; Arm. marg. It seems to be allied to Sax. merg, mearh; D. merg, marrow, and to be named from its softness; Eth. መረገ, clay, gypsum, or mortar. See Marrow.]

A species of calcarious earth, of different composition, being united with clay or fuller's earth. In a crude state it effervesces with acids. It is found loose and friable, or more or less indurated. It possesses fertilizing properties and is much used for manure. Marl is composed of carbonate of lime and clay in various proportions. Cleaveland.