Geological depression in the context of Aoukar

The Afar Triangle (also called the Afar Depression) is a geological depression caused by the Afar triple junction, which is part of the Great Rift Valley in East Africa. The region has disclosed fossil specimens of the very earliest hominins; that is, the earliest of the human clade, and it is thought by some paleontologists to be the cradle of the evolution of humans. The Depression overlaps the borders of Eritrea, Djibouti and the entire Afar Region of Ethiopia; and it contains the lowest point in Africa, Lake Assal, Djibouti, at 155 m (509 ft) below sea level.

The Awash River is the main waterflow into the region, but it runs dry during the annual dry season, and ends as a chain of saline lakes. The northern part of the Afar Depression is also known as the Danakil Depression. The lowlands are affected by heat, drought, and minimal air circulation, and contain the hottest places (year-round average temperatures) of anywhere on Earth.

A watering hole or waterhole is a geological depression in which a body of water forms, usually a pond or a small lake. A watering hole is "a sunken area of land that fills with water".

Watering holes may be ephemeral or seasonal. Ephemeral rivers sometimes form waterholes in geological depressions or areas scoured by erosion, and are common in arid regions of Australia. In Australia, the term "billabong", often defined as a type of oxbow lake (an isolated crescentic pond left behind after a river loop is cut off when the river channel changes course), is also used to refer to other types of waterholes. While they exist in both wetlands and arid lands, they are of particular importance in desert areas of Australia, where they are often the only water source for native animals, people, and livestock, and provide critical habitat for a number of wildlife species. Their existence is being threatened by climate change. Desert waterholes are often found in dry hilly areas, sustained by discharge of groundwater, remaining for long periods after flood events or normal flows of rivers and creeks. Depending on the climate, they can be permanent or semi-permanent depending on climatic conditions. They are of particular importance to Indigenous Australians in desert areas, providing water to the local population as well as attracting animals which are used as food, and sustaining plants which can be used for food (bush tucker), bush medicine, tools, shelter, and clothing. They may also be of cultural significance, as places to conduct ceremonies, and are usually named and part of their jukurrpa (Dreaming) stories.