Buildings and sculptures of the ancient Maya site at Copán in western Honduras show significant stone decay. The andesites, which were used for buildings and sculptures, show various phenomena of decay: a powdery decomposition of the surface, a loosening of thicker plates, a deep cavritation, and an intense growth of microorganisms. These damages result from the action of intense rainfalls and the moisture of the soil, which cause chemical as well as physical alterations to the stone. For preservation it is necessary to consolidate the stone, to waterproof the surface, to protect against the dampness of the soil, and to prevent the growth of microorganisms. See also AATA 21-2111 for more information on stone conservation in tropical climates.