What is "marl"

Greensand \Green"sand`\ (-s[a^]nd`), n. (Geol.) A variety of sandstone, usually imperfectly consolidated, consisting largely of glauconite, a silicate of iron and potash of a green color, mixed with sand and a trace of phosphate of lime.

Note: [hand]Greensand is often called marl, because it is a useful fertilizer. The greensand beds of the American Cretaceous belong mostly to the Upper Cretaceous.

"clayey soil used for fertilizer," late 14c., from Old French marle (Modern French marne), from Late Latin marglia, diminutive of Latin marga "marl," which is said by Pliny to be a Gaulish word, but modern Celtic cognates are considered to be borrowed from English or French. As a verb by late 14c. Medieval Latin margila is the source of Dutch mergel, German Mergel.

alt. A mixed earthy substance, consisting of carbonate of lime, clay, and possibly sand, in very variable proportions, and accordingly designated as calcareous, clayey, or sandy. n. A mixed earthy substance, consisting of carbonate of lime, clay, and possibly sand, in very variable proportions, and accordingly designated as calcareous, clayey, or sandy. vb. To cover, as part of a rope, with marline, marking a peculiar hitch at each turn to prevent unwinding.

n. a loose and crumbling earthy deposit consisting mainly of calcite or dolomite; used as a fertilizer for soils deficient in lime

__NOTOC__ Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and silt. The dominant carbonate mineral in most marls is calcite, but other carbonate minerals such as aragonite, dolomite, and siderite may be present. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay and calcium carbonate, formed under freshwater conditions; specifically an earthy substance containing 35–65% clay and 65–35% carbonate. It also describes a habit of coralline red alga. The term is today often used to describe indurated marine deposits and lacustrine (lake) sediments which more accurately should be named 'marlstone'. Marlstone is an indurated (resists crumbling or powdering) rock of about the same composition as marl, more correctly called an earthy or impure argillaceous limestone. It has a blocky subconchoidal fracture, and is less fissile than shale. The term 'marl' is widely used in English-language geology, while the terms Mergel and Seekreide (German for "lake chalk") are used in European references.

The lower stratigraphic units of the chalk cliffs of Dover consist of a sequence of glauconitic marls followed by rhythmically banded limestone and marl layers. Upper Cretaceous cyclic sequences in Germany and marl– opal-rich Tortonian- Messinian strata in the Sorbas basin related to multiple sea drawdown have been correlated with Milankovitch orbital forcing.

Marl as lacustrine sediment is common in post glacial lake-bed sediments, often found underlying peat bogs. It has been used as a soil conditioner and acid soil neutralizing agent.

Marl is calcium carbonate or lime-rich sedimentary rock.

Marl may also refer to:

• Marl, North Rhine-Westphalia, a city in North Rhine-Westphalia, Germany
• Marl, Lower Saxony, a municipality in Lower Saxony, Germany
• Marl, another name for the western barred bandicoot
• USS Marl (IX-160), a Trefoil-class concrete barge of the United States Navy
• Marl Hill, an historic building in Virginia
• Marl Kingdom, a series of RPGs created by Nippon-Ichi
• Marled yarn is made from strands of different-colored yarn twisted together