Geologic Unconsolidated Mineral Substrate surface has no trace of Gravel and is < 10% Sand (particles 0.0625 millimeters to 2 millimeters in diameter); the remaining Silt-Clay mix is 67% or more Silt (particles 0.0040 millimeters to < 0.0625 millimeters in diameter).

Editorial Change (defintion re-worded)

S

When classifying Mixes, or when there is a need to identify specific particle sizes beyond the Subgroup definitions, the Subgroup terms for the Gravel Group (Boulder, Cobble, Pebble, Granule), Sand Group (Very Coarse Sand, Coarse Sand, Medium Sand, Fine, Sand, Very Fine Sand), and Mud Group (Silt, Silt-Clay, Clay) may optionally be substituted for the Group term. Examples: Muddy Sandy Gravel -> Silty Sandy Gravel, Slightly Gravelly Sandy Mud -> Slightly Gravelly Sandy Clay, Gravelly Muddy Sand -> Gravelly Muddy Coarse Sand, Slightly Gravelly Sand -> Slightly Gravelly Medium Sand

See also: Implementation Guidance for all Substrate Component units.

Silt

cmecs:CMECS_00000755

Silt

Anthropogenic Impact, aRPD and RPD Depth, Benthic Depth Zones, Co-Occurring Elements, Coral Reef Zone, Energy Intensity, Induration, Percent Cover (Fine), Mineral Precipitate, Percent Cover (Coarse), Seafloor Rugosity, Small-Scale Slope, Substrate Descriptor, Substrate Layering, Surface Pattern, Temporal Persistence

Original Unit

CMECS Substrate Component: Substrate Subgroup