Natural World Heritage criteria

To be declared a World Heritage site must meet various criteria, among which are:

Natural Criteria
(Vii) contain superlative natural phenomena or areas constitute an exceptional natural beauty and aesthetic importance;
(Viii) be outstanding examples representing different periods in Earth history, including the record of evolution, of significant ongoing geological processes in the development of landforms, or significant geomorphic or physiographic features;
(Ix) be outstanding examples representing significant ecological and biological processes in the evolution and development of ecosystems and communities of plants and terrestrial, freshwater, coastal and marine animals;
(X) contain the most important and significant for the in situ conservation of biological diversity, natural habitats, including those containing threatened species of outstanding universal value from the point of view of science or conservation.