Q. What Is the Blue Mountains World Heritage Area?

• Closest to Sydney is the World Heritage area of the Greater Blue Mountains with the lower reaches of the Blue Mountains National Park able to be accessed from Glenbrook, first town on the highway up the mountains.

  In the southwest, Thirlmere Lakes National Park is close to the town of, yes, Thirlmere just out of Picton.

  Yengo and the Wollemi National Park, as well as the northern section of Blue Mountains National Park, are close to Sydney's northwest suburbs.

The area lies 60 to 180 kilometres inland from central Sydney, New South Wales.

In common use, it is the transportation and development corridor, marked by the spiraling Great Western Highway, that locals and visitors refer to when speaking of the Blue Mountains.

The World Heritage area comprises 1.03 million hectares of mostly forested land on a sandstone plateau. It is an area almost a third the size of Belgium, or twice the size of Brunei.

In the World Heritage area are the Blue Mountains, Wollemi, Yengo, Nattai, Kanangra-Boyd, Gardens of Stone and Thirlmere Lakes National Parks, and the Jenolan Caves Karst Conservation Reserve.

The area rises from less than 100 metres above sea level to 1300 metres at the highest point.

In declaring the Greater Blue Mountains area a World Heritage site, it was judged to have outstanding examples "representing significant on-going ecological and biological processes in the evolution and development of terrestrial, fresh water, coastal and marine ecosystems and communities of plants and animals" as well as containing the "most important and significant natural habitats for in-situ conservation of biological diversity, including those containing threatened species of outstanding universal value from the point of view of science or conservation."

Among the relict species of global significance is the recently-discovered Wollemi pine, a "living fossil" dating back to the age of the dinosaurs.