Definition: Gravel is an environmental material which is composed of pieces of rock that are at least two millimeters (2mm) in its largest dimension and no more than 75 millimeters.
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: The benthopelagic zone biome comprises regions of the marine water column which usually coincide with the benthic boundary layer (BBL) - the layer of isothermal and isohaline water contiguous to the sea floor. A general reversal in the declining gradient of pelagic biomass may be observed here, perhaps explained by viable nutrition on the sea floor being resuspended by bottom currents. This zone typically extends 100 m above the seafloor, but may reach upto1000 m during benthic storms.
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).
