Definição: Any material within 2 m from the Earth's surface that is in contact with the atmosphere, with the exclusion of living organisms, areas with continuous ice not covered by other material, and water bodies deeper than 2 m.
Definição: Museum National d'Histoire Naturelle (MNHN), Paris, France. URL for main institutional website: http://www.mnhn.fr/museum/foffice/science/science/sommaire.xsp
