Geologic Unconsolidated Mineral Substrates with less than 50% cover of Consolidated Mineral Substrate where the Unconsolidated Mineral Substrate surface contains < 5% Gravel (particles 2 millimeters to < 4,096 millimeters in diameter).

Name change

Change in level up (subclass to class)

Attribute Changes (Unit Type)

Editorial Change (defintion re-worded)

S

The CMECS Coarse, Mixed, and Fine Unconsolidated Mineral Substrate Classes and subordinate units use Folk (1954) terminology to describe particle sizes of loose mineral substrates as shown in the ternary diagram in Figure 7.2 . Units with bracketed letters, e.g., [G], [(g)sM], correspond to the labeled polygons in Figure 7.2, using conventions from Folk (1954).

See Also: Implementation Guidance for All Substrate Component Units.

The Co-occurring Elements Modifier (see Section 10.6.2, p. 213, FGDC-STD-018-2012) may be used to describe mixes of origins as well as the presence of secondary substrate units within the observational unit (i.e., image frame, sampling grid cell, etc.)

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

Due to the importance of different particle sizes of Gravel as habitat for many organisms, Gravel subgroup particle sizes (Boulder, Cobble, Pebble, Granule) must be identified whenever particle sizes are known or can be estimated within any mix and at any level of classification. Examples: Gravel Mixes -> Pebble Mixes, Muddy Sandy Gravel -> Muddy Sandy Cobble, Gravelly Sand -> Bouldery Sand

Fine Unconsolidated Mineral Substrate

cmecs:CMECS_00000344

Fine Unconsolidated Mineral Substrate

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

Folk, R.L., 1954. “The Distinction between Grain Size and Mineral Composition in Sedimentary-Rock Nomenclature.” The Journal of Geology 62: 344-359.

Derived Unit

CMECS Substrate Component: Substrate Class