A vlei /fleɪ/ (Afrikaans pronunciation: [flɛi]) is a shallow minor lake, mostly of a seasonal or intermittent nature. It even might refer to seasonal ponds or marshy patches where frogs and similar marsh dwellers breed. Commonly, vleis vary in their extent, or even in the presence or absence of water, according to the fall of rain or dryness of the season. In terms of water salinity, vleis may be freshwater, saltwater, or brackish. Over time a vlei may degrade into a salt pan or clay pan, such as Dead Vlei or Sossusvlei.