The Grose Valley is a rugged valley in the Blue Mountains, New South Wales, Australia. It has been formed by the Grose River, the headwaters of which are in the Mount Victoria area. The valley is located between the Great Western Highway and Bells Line of Road, the two major routes across the Blue Mountains. The majority of the valley falls within the Blue Mountains National Park. Grose wilderness features The Grose Wilderness contains some of the most dramatic gorge and canyon landscapes of the entire Sydney basin sandstone region. The Grose also constitutes one of the most accessible wilderness areas for bushwalking or public observation from its escarpment margins. Geology The geology of the area consists of Triassic sandstones and underlying Permian sedimentary rocks. A number of basalt-capped peaks dominate the area, notably Mount Banks and Mount Hay. The Grose River and its tributaries have eroded an extensive labyrinth of gorges and canyons through the Hawkesbury (upper) and Narrabeen (lower) group sandstones, exposing cliffs of commonly over and up to in height (Banks Wall). The Burramoko Head sandstone in the upper and middle Grose gorges possesses weathering tendencies of breakage along vertical joints and has consequently yielded some of the sheerest cliff faces in the Blue Mountains. The wilderness contains 80% of the Grose River catchment. The river flows to the Nepean-Hawkesbury through an undisturbed environment for all but its final . Consequently, the Grose has substantial wild river values, as do its major tributaries such as Wentworth Creek and Carmarthen Brook. Flora The bulk of the vegetation in the wilderness is dry open forest and woodland, dominated by Eucalyptus sieberi and E. piperita above altitude with Eucalyptus oblonga, E. globoidea, E. agglomerata and Angophora costata becoming dominant at lower altitudes. Plateau areas have thinner or waterlogged soils and generally support heath or low open woodland communities. Within the sheltered and well watered canyon environments closed forests commonly occur, with typical species being coachwood, sassafras and possumwood. On the isolated basalt caps the fertile soils support taller eucalypt forests of E. viminalis, E. blaxlandii and E. fastigata. A small area of alluvial sediments deposited in the upper Grose Valley during the Quaternary supports a tall moist open forest dominated by E. deanei, E. oreades, E. notabilis and E. cypelocarpa. The Blue Gum Forest is included in this forest type. Fauna The river is known habitat for platypus and certain