There are no proper watercourses in the park. Creek beds and gullies are mostly found in the valleys around Kata Tjuṯa. These are usually dry, except after heavy rains, but water can stay under the sand for months. The soils in the park contain high levels of clay, which stops water from soaking into the ground too quickly. The only lasting surface water in the park is Muṯitjulu Waterhole (""), at the base of Uluṟu. It has many waterholes (pockets of water) that have formed by rain running off the rock down its fracture lines. They are the only lasting spots of water above the ground for hundreds of kilometres in any direction. They normally have some water in them for the whole year.