Definition: A group of hydrous aluminium phyllosilicate (phyllosilicates being a subgroup of silicate minerals) minerals (see clay minerals), that are typically less than 2micrometres in diameter. Clay consists of a variety of phyllosilicate minerals rich in silicon and aluminium oxides and hydroxides which include variable amounts of structural water.
Definition: Organic matter in soil which has reached a point of stability, where it will break down no further and might, if conditions do not change, remain essentially as it is for centuries, or millennia.
Definition: An area of land of low topographic relief that historically supported grasses and herbs, with few trees, and having generally a mesic (moderate or temperate) climate. Dominated by tall grasses (contrast steppe).
Definition: A wetland that features permanent inundation of large areas of land by shallow bodies of water, generally with a substantial number of hummocks, or dry-land protrusions.
Definition: A habitat that is in or on a body of water containing low concentrations of dissolved salts and other total dissolved solids (<0.5 grams dissolved salts per litre).