hanging swamps provide habitat for the endangered and endemic Blue Mountains water skink (Eulamprus leuraensis). The rocky sandstone complexes of the plateau provide habitat for some specialised and rare native animal species (e.g. the broad-headed snake, Hoplocephalus bungaroides). Woodland communities are habitat for mammals such as the red-necked swamp wallaby, brush-tailed rock wallaby and eastern pygmy possum. History Aboriginal history Aboriginal artefacts have been found close to the Blue Gum Forest. European history The Grose River has cut a deep gorge through the area as it makes its way east towards the Hawkesbury River. Sheer sandstone cliffs standing hundreds of metres above the river make for spectacular scenery and can be viewed extensively from the Blackheath area, where there are a number of accessible lookouts, the best known being Govetts Leap. The valley can also be viewed from lookouts near Bells Line of Road and points outside Mount Victoria. It is named after Francis Grose. Charles Darwin described the Grose Valley as "stupendous… magnificent" when he visited in 1836. In 1859 some of the first photographs in Australia were taken in the valley. At various times there were proposals for rail lines and dams but these have not proceeded. In 1931, the valley was the subject of one of Australia's first forest conservation battles. Within the valley, the Blue Gum Forest is one place that stands out from the rest of the valley. It consists predominantly of towering Blue Gum trees (Eucalyptus deanei, also known as Deane's Gums, or Broad-leafed gums), with a thin understorey because the tall trees inhibit the growth of ground cover by blocking most of the sunlight. Protected by the Blue Mountains National Park, the forest can be accessed only on foot, with several trails from different parts of the Grose Valley and adjacent canyons meeting in the forest. Bushwalking trails There are a number of walks through the valley, with various entry, exit points and valley arms offering a range of permutations to explore. A moderate-grade day walk covering approximately in five hours starts at Perrys Lookdown and descends sharply to the valley floor. Crossing through a corner of the Blue Gum Forest, the track goes south through the Acacia Flat camp ground, following the Govetts Creek. Passing several abandoned campgrounds, the path forks at Junction Rock; the route to Govetts Leap was closed in October 2003, following a landslide, and was reopened in December