Arbol de Piedra (Rock Tree) is named after its unique appearance, which resembles a surrealist vision of a tree. It is located in the sand dunes of the Eduardo Avaroa Andean Fauna National Reserve, Potos??Department of Bolivia. de Piedra measures about five metres tall and has been formed by wind erosion over millions of years. The base of this isolated rock formation predominantly consists of quartz, which is sensitive to erosion. The strong winds in the area carry sandstone and salt, which increase the erosion. The upper part of the Arbol de Piedra is more resistant to erosion resulting in it?瑼?shape. Part of the structure has fallen off and lies alongside. The rock has been declared a natural monument.