Siltdominated

Siltdominated is a descriptive term used in geology, sedimentology, and soil science to describe materials in which silt-sized particles constitute the majority of the grain-size distribution. Silt, typically defined as particles about 2 to 63 micrometers in diameter, imparts a texture that sits between sand and clay, with moderate cohesion and water-holding capacity.

In practice, siltdominated implies that silt makes up the largest share of the sample relative to sand and clay, though exact thresholds vary among classification schemes. Soils described as siltdominated often fall into texture classes such as silt loam, silty loam, or silty clay loam, depending on the relative amounts of the other fractions.

Formation contexts for siltdominated sediments include low- to moderate-energy environments where fine particles settle from suspension, such as floodplains, lakes, and estuaries. Wind deposition can also produce siltdominated deposits, notably loess, which consists largely of wind-blown silt and is widespread in some regions.

Properties and implications of siltdominated textures include relatively high porosity and water-holding capacity, but weaker structure and slower drainage than sandy soils. They can be prone to compaction when disturbed and may be susceptible to erosion by water or wind if left bare. In geotechnical terms, siltdominated deposits can exhibit low shear strength when saturated and may show moisture-sensitive behavior.

Measurement and description typically rely on particle-size analysis (sieving, hydrometry, or laser methods) to determine the fractions, with a sample labeled siltdominated when the silt fraction is the most prominent component.