Mode of deposition - first (uppermost)

Attribute definition
Attribute Label MDEP1
Title Mode of deposition - first (uppermost)

The mode of deposition of the uppermost underlying parent material. First used in SLC 3.0

Classes Mode of Deposition. 37 classes. First used in SNT 1.0.

Code Class Description
ANTH Anthropogenic

Materials modified by people,including those associated with mineral exploitation and waste disposal. They include materials deposited as a result of human activities or geological materials modified artificially so that their physical properties (structure, cohesion, compaction) have been drastically altered. Examples are areas of landfill, spoil heaps, open-pit mines and levelled irrigated areas.

COLL Colluvial

Massive to moderately-well stratified, nonsorted to poorly sorted sediments with any range of particle sizes from clay to boulders that have reached their present position only by direct, gravity-induced movement. Processes include slow displacements such as creep and solifluction and rapid movements such as earth flows.

EOLI Eolian

Eolian material deposited by wind: uniform deposit of very fine sand and silt.

FLEO Fluvioeolian


FLLC Fluviolacustrine


FLUV Fluvial

These sediments generally consist of gravel and sand with a minor fraction of silt and rarely of clay. The gravels are typically rounded and contain interstitial sand.

FNPT Fen Peat

These deposits consist of sedge peat derived primarily from sedges with inclusions of partially decayed stems of shrubs formed in a eutrophic environment due to the close association of the material with mineral-rich waters.

FOPT Forest Peat

This class is used for forest peatcovered or forest peat-filled areas where the water table is at or above the peat surface. The dominant peat materials are shallow to deep mesic to humic forest and fen peat formed in a eutrophic environment resulting from strong water movement from the margins or other mineral sources.

GLFL Glaciofluvial

Material moved by glaciers and subsequently sorted and deposited by streams flowing from the melting ice. The deposits are stratified and may occur in the form of outwash plains, deltas, kames eskers, and kame terraces. See also glacial drift and till.

GLLC Glaciolacustrine

Used where there is evidence that the lacustrine materials were deposited in contact with glacial ice. One of the following characteristics must be present:

  • kettles or an otherwise irregular surface that is neither simply the result of normal settling and compaction in silt nor the result of piping
  • slump structures resulting from loss of support caused by melting of retaining ice
  • presence of numerous ice-rafted stones in the lacustrine silts.

GLMA Glaciomarine


LACU Lacustrine

Sediment, generally consisting of either stratified fine sand, silt, and clay deposited on the lake bed, or moderately-well sorted, stratified sand and coarse materials that consist of near lake shore or beach deposits. These materials have either settled from suspension in bodies of standing fresh water or accumulated at their margins through wave action.

LATL Lacustro-Till


MARI Marine

Unconsolidated deposits of clay, silt, sand, or gravel that are well to moderately well sorted and well to moderately well stratified (in some places containing shells). The deposits have settled from suspension in salt or brackish water bodies or have accumulated at their margins through shoreline processes such as wave action and longshore drift. Nonfossiliferous deposits may be judged marine if they are located in an area that may reasonably be considered to have contained salt water at the time the deposits were formed.

RESD Residual

Unconsolidated, weathered, or partly weathered mineral soil material that accumulates by in situ disintegration of bedrock.

SAPR Saprolite

This material is rock and contains a high proportion of residual silts and clays formed by alteration, chiefly by chemical weathering.

The rock remains in a coherent state, interstitial grain relationships are undisturbed, and no downhill movement due to gravity has occurred. The process is assumed to be active. Examples: rotten rock containing corestones.

SEPT Sedimentary Peat

Coprogenous earth is composed of aquatic plant debris modified by aquatic animals. It makes slightly viscous water suspensions and is slightly plastic but not sticky. The material shrinks upon drying to form clods that are difficult to rewet and commonly crack along horizontal planes. It has very few or no plant fragments recognizable to the naked eye, a pyrophosphate index of 5 or more, and a dry color value of less than 5.

SPPT Sphagnum Peat

These deposits consist of sphagnum or forest peat formed in an ombrotrophic environment caused by the slightly elevated nature of the bog. They tend to be disassociated from nutrient-rich ground water or surrounding mineral soils.

TILL Till (Morainal)

Morainal material (till) deposited by glacial ice: a mixture of boulders, sand, silt, and clay.

UNDM Undifferentiated mineral

A sequence of more than three types of genetic mineral materials outcropping on a steep erosional escarpment. This complex class is to be used where units relating to individual genetic materials cannot be delimited separately at the scale of mapping. It may include colluvium derived from the various genetic materials and resting upon the scarp slope.

UNDO Undifferentiated organic

A layered sequence of more than three undifferentiated types of organic material (>30% organic matter by weight).

VOLC Volcanic

Volcanic pumice and ash.

Code Class Description
RKUD Undifferentiated

Bedrock, undifferentiated

RKIA Igneous, acidic

Igneous, acidic bedrock (dominantly granite)

RKIB Igneous, basic

Igneous, basic bedrock (dominantly basalt)

RKIC Igneous, basic coarse

Igneous, basic coarse bedrock (coarse grained basalts)

RKIF Igneous, basic fine grained

Igneous, basic fine grained bedrock (dominantly andesites)

RKCA Calcareous

Calcareous bedrock (dominantly sandstone and shale)

RKLS Limestone

Limestone bedrock (limestone and dolomite)

RKSH Shale

Shale bedrock

RKSS Sandstone

Sandstone bedrock

RKSM Siltstone and mudstone

Siltstone and mudstone bedrock

RKSP Schist and phyllite

Schist and phyllite bedrock

RKSA Slate

Slate bedrock

RKQU Quartzite

Quartzite bedrock

RKGN Gneiss

Gneiss bedrock

Code Class Description
- Not Applicable

Not Applicable