Fen in the context of "Swamp"

Peat is an accumulation of partially decayed vegetation or organic matter. It is unique to natural areas called peatlands, bogs, mires, moors, or muskegs. Sphagnum moss, also called peat moss, is one of the most common components in peat, although many other plants can contribute. The biological features of sphagnum mosses act to create a habitat aiding peat formation, a phenomenon termed 'habitat manipulation'. Soils consisting primarily of peat are known as histosols. Peat forms in wetland conditions, where flooding or stagnant water obstructs the flow of oxygen from the atmosphere, slowing the rate of decomposition. Peat properties such as organic matter content and saturated hydraulic conductivity can exhibit high spatial heterogeneity.

Peatlands, particularly bogs, are the primary source of peat; although less common, other wetlands, including fens, pocosins and peat swamp forests, also deposit peat. Landscapes covered in peat are home to specific kinds of plants, including Sphagnum moss, ericaceous shrubs and sedges. Because organic matter accumulates over thousands of years, peat deposits provide records of past vegetation and climate by preserving plant remains, such as pollen. This allows the reconstruction of past environments and the study of land-use changes.

Mud (from Middle Low German mudde, mod(de) 'thick mud', or Middle Dutch) is loam, silt or clay mixed with water. Mud is usually formed after rainfall or near water sources. Ancient mud deposits hardened over geological time to form sedimentary rock such as shale or mudstone (generally called lutites). When geological deposits of mud are formed in estuaries, the resultant layers are termed bay muds. Mud has also been used for centuries as a construction resource for mostly houses and also used as a binder. An Old English word for it was fen, now in most dialects referring to a type of wetland.

A carr is a type of waterlogged wooded terrain that, typically, represents a succession stage between the original reedy marsh and the likely eventual formation of forest in a sub-maritime climate. Carrs are wetlands that are dominated by shrubs rather than trees. The carr is one stage in a hydrosere: the progression of vegetation beginning from a terrain submerged by fresh water along a river or lake margin. In sub-maritime regions, it begins with reed-marsh. As the reeds decay, the soil surface eventually rises above the water, creating fens that allow vegetation such as sedge to grow. As this progression continues, riparian trees and bushes appear and a carr landscape is created – in effect a wooded fen in a waterlogged terrain. At this stage, overall, unlike the overwhelming acidity of decaying reeds, the pH is not too acidic and the soil is not too deficient in minerals, making a habitat for endemic and other wildlife. Characteristic water-tolerant trees include alder and willow.

A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials – often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muskeg; alkaline mires are called fens. A bayhead is another type of bog found in the forest of the Gulf Coast states in the United States. They are often covered in heath or heather shrubs rooted in the sphagnum moss and peat. The gradual accumulation of decayed plant material in a bog functions as a carbon sink.

Bogs occur where the water at the ground surface is acidic and low in nutrients. A bog usually is found at a freshwater soft spongy ground that is made up of decayed plant matter which is known as peat. They are generally found in cooler northern climates and are formed in poorly draining lake basins. In contrast to fens, they derive most of their water from precipitation rather than mineral-rich ground or surface water. Water flowing out of bogs has a characteristic brown colour, which comes from dissolved peat tannins. In general, the low fertility and cool climate result in relatively slow plant growth, but decay is even slower due to low oxygen levels in saturated bog soils. Hence, peat accumulates. Large areas of the landscape can be covered many meters deep in peat.

Fenrir (Old Norse 'fen-dweller') or Fenrisúlfr (Old Norse "Fenrir's wolf", often translated "Fenris-wolf"), also referred to as Hróðvitnir (Old Norse "fame-wolf") and Vánagandr (Old Norse 'monster of the [River] Ván'), is a monstrous wolf in Norse mythology. In Old Norse texts, Fenrir plays a key role during the events of Ragnarök, where he is foretold to assist in setting the world aflame, resulting in the collapse of humanity and society, and killing the god Odin.

Fenrir, along with Hel and Jörmungandr, is a child of Loki and female jötunn Angrboða. He is attested in the Poetic Edda, compiled in the 13th century from earlier traditional sources, and the Prose Edda and Heimskringla, composed in the 13th century. In both the Poetic Edda and Prose Edda, Fenrir is the father of the wolves Sköll and Hati Hróðvitnisson, is a son of Loki and is foretold to kill the god Odin during the events of Ragnarök, but will in turn be killed by Odin's son Víðarr.