 Ifet morality is the concept of things being transitory, existing only briefly. Typically the term ephemeral is used to describe objects found in nature, although it can describe the wide range of things, including human artifacts intentionally made to last for only a temporary period, in order to increase their perceived aesthetic value. With respect to unique performances, for example, it has been noted that ephemerality is a quality caused by the ebb and flow of the crowd's concentration on the performance and a reflection of the nostalgic character of specific performances. Because different people may value the passage of time differently, the concept of ephemerality is a relative one. An ephemeral water body is a wetland, spring, stream, river, pond or lake that only exists for a short period following precipitation or snow melt. They are not the same as intermittent or seasonal water bodies, which exist for longer periods, but not all year round. Examples of ephemeral streams are the Lune River in Rajasthan, India, Ufgab River in southern Africa, and a number of small ephemeral water corpses that drain tail up in northern Niger. Other notable ephemeral rivers include the Todd River and Sandal River in central Australia as well as the Sun River, Batha River and the Tridbankos River. Any indoor hike basin, or closed basin, that contains a plyo or dry lake that its drainage low point can become an ephemeral lake. Examples include Lake Carnegie in western Australia, Lake Powell in New South Wales, Mystic Lake and Rogers Lake in California, and Severe Lake in Utah. Even the driest and lowest place in North America, Death Valley more specifically that water basin became flooded with a short-lived ephemeral lake in the spring of 2005.4. There are also ephemeral islands such as Banyu and Wuhu and Home Reef. These islands appear when volcanic activity increases their height above sea level, but disappear over several years due to wave erosion. Bassasda, India, on the other hand, is a near sea level island that appears only at low tide.