 Complete the following phrase:  In the far west of the national park, the gibber plains are replaced by sandhills of the Strzelecki Desert. Cameron Corner is a remote but popular tourist destination where the states of New South Wales, South Australia and Queensland meet. Also in this part of the park is Fort Greythe fourth camp ground and a heritage site. The holding yards visible here and a remt from the explorer Charles Sturt. The fort is a stockade that was built to protect Sturts supplies and prevent the exploration partys sheep from wandering away. While searching for a fabled inland sea, Captain Charles Sturt, after whom the park is named, spent a year in the area. Fort Grey is sited on the edge of the ephemeral, and 