<P> The area is semi-arid, average rainfall being approximately 250mm per annum . </P> <P> Twenty species of mammals are currently recorded at Willandra, of which bats are the most diverse group . There are some 40 species of reptiles and amphibians . There are 137 recorded species of bird life including parrots, cockatoos and finches . </P> <P> Willandra's archaeological record demonstrates continuous human occupation of the area for at least 40,000 years . It was part of the history of inland exploration (Burke and Wills expedition) and of the development of the pastoral industry in western New South Wales . The area contains a relict lake system whose sediments, geomorphology and soils contain an outstanding record of low - altitude, non-glaciated Pleistocene landscape . The area contains outstanding examples of lunettes including Chibnalwood Lunette, the largest clay lunette in the world . Living in the area provides the opportunity to experience the natural harshness and beauty through all seasons . The Willandra's traditionally affiliated Aboriginal people proudly identify themselves with this land . The Willandra's primary producer landholder families have links with the European settlement of the region . The remoteness of the area creates the neighbourly support and a sense of community, in times of need whilst at the same time the isolation promotes self - sufficiency . The region has a Pleistocene archaeological record of outstanding value for world pre-history and is significant for understanding early cultural development in this region . The area is the site of discovery of the Mungo Geomagnetic Excursion, one of the most recent major changes of the earth's magnetic field . The area is capable of yielding information relating to the evolution of climates and environments in south - eastern Australia . It has importance in understanding the reversal of the earth's magnetic field . The Willandra Lakes Region comprising 240,000 acres was inscribed on the World Heritage List in 1981 for both outstanding cultural and natural universal values: as an outstanding example representing the major stages in the earth's evolutionary history; as an outstanding example representing significant ongoing geological processes; and for bearing an exceptional testimony to a past civilization . </P> <P> Willandra Lakes was listed on the New South Wales State Heritage Register on 2 April 1999 having satisfied the following criteria . </P>

Why is willandra lakes a world heritage site