The Marne (rock)

See also: the Marne

The marl which one also names, according to its quality, Tuffeau or Pierre de France or stone of Maastricht, is a Sedimentary rock containing Calcaire CaCO3 and Argile in about equivalent quantities (35% to 65%).

Use

Since the age of iron one extracts the marl in the form of blocks from stone bound for construction. One finds this material abundant, easy to extract and work in many old buildings modest or prestigious. With the exhaustion of the marl careers of quality, the low hardness of material and its bad resistance will lead however to a progressive abandonment of this use. Appeared there is little the phenomenon of the Acid rains constitutes a frightening enemy of the buildings built out of marly materials. The last layers of marnes of quality are thus reserved for the restoration.

At the 19th century one industrialized the production of lime. The marl with its high calcareous composition and its abundance was an ideal ingredient for the uses which did not require into final a lime of an high level of purity, the development of mortar for example. The Ciment Portland of today always uses the marl like principal ingredient.

Crushed it is also a product of amendment of the cultures in order to make the grounds less acid.

Marl-pits

See also: Marl-pit

The marl was extracted as construction material as soon as the metal tools were known.

The marl-pits also made it possible to extract the Craie to amend the arable lands.

At the time, to remove important layers of topsoil was impossible; one thus started to extract where the marl levelled and one continued by digging networks of galleries. At our time, the marl is extracted in gigantic careers with open sky, generally close to the cement factory where it is transformed into cement.

Old the marl-pits often underground and was disseminated (extraction with more close, to limit transport). After use they were stopped, their sites being only located by trees. With the wire of time (and regroupings), these trees generally isolated in the middle of the fields disappeared and the memory from the site with them.

The phenomena of erosion and dissolution lead sometimes to collapses. Their consequences are particularly serious so constructions were built above. The Normandy is regularly victim of accidents of this nature.

Uses

The marl is used since mists of time. In France, one generally uses it under the name of white Spain, of Meudon, Toulouse, or of Champagne (Troyes).

The career of Meudon is not any more exploited but became a classified site.

It can be used pure, treated and/or mixed with various materials (rices, excrements animal, etc)

Painting

It can be used with manufacture as Pigment S, of Enduit S, like Gesso.

The fact that it is of natural origin makes them a priori less toxic than of other pigments.

The whiting in particular was very much used during the Renaissance.

It is also used by activists of the movement Antipub to repaint the billboards. From a legal point of view, the use of the whiting does not constitute indeed a Dégradation.

Ceramicses

This thanks to the Carbonate of calcium that the marl contains.

Cement

Especially for the cement of Glazier.

Pieces of housework

The whiting is used for its absorbing virtues, abrasive, and its capacity to make shine.

Calendar

The marl celebrates the 17 Nivôse in the republican Calendrier.

EXTERNAL BONDS

  • ''' History of the manufacture of the precipitated chalk '''

  • Marl-pits and sink-holes on the site of the university of the Havre
  • the Marl-pit in Normandy, if you are confronted with a problem of marl-pit, you can start by consulting this site
  • the precipitated chalk on pourpre.com, the site of the color
  • the uses in visual art

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