Soil aggregate stability typically have a higher water infiltration rate, allowing more water into the soil profile faster, and are not susceptible to water ponding. Soil aggregates are formed due to flocculation and cementation processes, and are enhanced by physical and biological processes. Primary soil particles (sand, silt, and clay) are subjected to these processes, and can stick together to form larger sub-microaggregates (< 250 μm), microaggregates, and macroaggregates (> 250 μm). It has been suggested that soil aggregates form hierarchically, meaning larger less dense aggregates are composed of smaller more dense aggregates (Kay, 1990; Oades, 1993). Flocculation refers to a state when
Geology of Great Britain is a varied distribution of unconsolidated material of more recent origin. It includes material deposited by glaciers (boulder clay, and other forms of glacial drift such as sand and gravel). "Drift" geology is often more important than "solid" geology when considering building works, drainage, siting water boreholes, sand and gravel resources and soil fertility. Although "drift" strictly refers to glacial and fluvio-glacial deposits, the term on geological maps has traditionally included other material including alluvium, river terraces, etc. Recent maps use the terms "bedrock" and "superficial" in place of "solid" and "drift". This description of the geological history of Great