Fen

A fen is a peat accumulating wetland fed by mineral rich ground or surface water, one of the main wetland types alongside marshes, swamps, and bogs. Fens and bogs are both peat forming ecosystems, together known as mires, but a fen's water chemistry, higher in minerals and less acidic, comes from that groundwater or surface water input. As peat builds up in a fen, groundwater input can be reduced or cut off, and the fen can become more acidic over time, gradually turning into a bog. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/