Morphosedimentological Zones

The morphosedimentological zones theme relates to deposits associated with the surficial geology of the area. The zone boundary represents the extent and geometry of an unconsolidated sediment unit (or surficial deposit) and constitutes a map unit. Each unit associated with a surficial deposit is identified by a distinct colour and code. The codes consist of one or two capital letters that define the depositional environment (e.g. G = glacial sediments, GL = glaciofluvial sediments, etc.). They may also contain one or more lower case letters to differentiate between different types of surficial deposits within the same category.

The list of symbols is also available in PDF format.

On surficial deposits maps of the Bulletin Quaternaire, the legend is ordered according to the stratigraphic succession of morphosedimentological zones in the same order as presented on this page. It may also include additional information specific to the area mapped, such as lithological composition, thickness, distribution of units, etc.

Postglacial

Antropogenic Deposit

Slope Deposits

Sediments deposited on a slope and whose main mechanism of deposition is gravity.

Organic Sediments

Organomineral sediments consisting of more or less decomposed peat, sphagnum moss or Cyperaceae. These organosedimentary accumulations generally form in poorly drained areas or areas with an outcropping water table, such as swamps and peat bogs.

Eolian Sediments

Sediments grouping deposits, generally sandy, remobilized by the wind and composed essentially of very well sorted fine sand. These deposits form dune accumulations or thin beds of variable area.

Alluvial Sediments

Sediments deposited along watercourses of the present river system as a result of erosion of older Quaternary formations. These sediments include alluvium deposited in former river channels.

Lacustrine Sediments

Sediments deposited in present-day lake basins. These sediments mainly include nearshore, beach and deltaic sands and gravels. These deposits may also include reworked sediments from underlying units.

Marine Sediments

Sediments deposited in postglacial seas that invaded, during deglaciation, territories depressed by glacial-isostatic sinking. These sediments mainly include nearshore, beach and deltaic sands and gravels, as well as silts and clays generally containing fossils deposited in deep water. These deposits may also include reworked sediments from underlying units.

Last Glaciation

Glaciomarine Sediments

Sediments deposited in postglacial seas (Champlain, Tyrell, Goldwaith, Iberville and Laflamme Seas) near or in front of an ice margin. Composed mainly of silt, sand, clay or diamicton. These sediments contain a very cold water fauna or are non-fossiliferous.

Glaciolacustrine Sediments

Sediments deposited in proglacial lakes (e.g. Candona Lake).

Glaciofluvial Sediments

Stratified sediments deposited by meltwater at or near the glacier. Units below the marine or glaciolacustrine boundary have generally been reworked by waves and currents during submergence or following flooding.

Glacial Sediments

Sandy-silty to silty-clayey matrix diamicton, olive-grey on the shield, to grey or brownish on the Palaeozoic platform, and directly deposited by the glacier. Reworking by waves and currents can be locally important below the marine limit, but is mostly very superficial, of the order of 50 cm and less. In contrast, the washed-out surface is often characterized by concentrations of metric boulders. The content of Precambrian crystalline pebbles varies from 100% on the shield to <10% on the Paleozoic platform. On the platform, the till matrix may be carbonatized depending on the nature of the eroded substrate.

Ancient Quaternary Formation

Ancient Quaternary Formation

Pre-Quaternary

Bedrock

Rock outcrops and bedrock having a thin cover of loose sediment (<30 cm).

↑ Deposit either reworked or deposited by anthropogenic activities (mines, towns, industries, etc.)Substratified to stratified sandy-gravelly pebbles forming fans and talus cones at the base of hillslopesFrost-shattered angular pebbles and boulders forming fans and talus cones at the base of hillslopesFrost-shattered angular pebbles and boulders deposited within avalanche paths along hillslopesAngular to subangular pebbles and boulders deposited on steep slopes and plastically deformed due to the presence of interstitial iceSilt and clay reworked by landslides, and generally occupying amphitheatres characterized by chaotic or stepped landforms at the base of landslide scars. Depending on the nature of the material covering clays and silts, these sediments may include sandy or gravely horizons incorporated by the landslidesColluvial deposit whose exact formation processes could not be determinedPeat decomposed to various degrees, deposited in fens or bogsOrganic sediment generally rich in mineral particles and deposited in palustrine (swampy) environments, characterized by open water bodies (ponds)Peat bog, marsh and swamp sediment whose exact formation processes could not be determinedFine sand with diffuse cross-bedded stratifications, deposited by the wind as parabolic dunes on freshly emerged coastal and alluvial sediments. May contain organic horizons such as paleosols. The wind erosion of stabilized dunes and other sandy surfaces may be reactivate if vegetation cover is removed, due to either forest fires or human activitiesMassive silt or sandy silt deposited by wind. Usually organized as thin veneer deposits less than a meter thickSand, sandy silt, gravelly sand and gravel commonly containing organic matter. Forms levees, bars and modern alluvial floodplainsLayered pebbles, gravel and sand forming gently sloping cones at the outlet of streams on flat land. Generally channeled surfaceSilt, sandy silt and sand generally containing organic fragments, commonly aquatic plants. Characterized by a massive, sublaminated or rhythmic structure. Sediments deposited during transgressive episodes and unconformably overlying older unitsSand, sandy silt, gravelly sand and gravel that may contain organic matter. Surface locally reworked by wind action and generally marked by levees and alluvial bars. Lowering of the base level is highlighted by the stepping of terracesSand, sandy silt and gravel, containing some organic matter, and deposited in areas overflowing the limits of the current river corridors. Estuarine facies are common in this unit. Surface generally marked by levees and alluvial bars, and reworked locally by wind action. Lowering of the base level is highlighted by the stepping of terracesAlluvial sediment deposited along watercourses, but whose exact formation processes could not be determinedStratified and well-sorted sand, gravelly sand and gravel, deposited at the mouth of streams flowing into the current lakes. Shows a flat surface generally marked by abandoned channels, and locally reworked by wind actionStratified and generally well-sorted sand, sandy silt, gravelly sand and gravel. Sediment deposited in shallow water during the plenilacustrine phase and during land emergence. Shows a surface generally marked by coastal and prelittoral shorelines, locally reworked by wind action. When associated with land emergence facies, this unit usually forms a thin veneer resting on deep-water sedimentGenerally laminated silt and clay forming locally rhythmites, and deposited in the deeper depressions of the current lacustrine basinsSediment deposited in a current lacustrine water plan, but whose exact formation processes could not be determinedGenerally massive or slightly stratified silt and sandy silt. Sediment deposited in intertidal or subtidal zones in sheltered bays or current sea arms, usually near large deltaic complexesStratified and well-sorted sand, gravelly sand and gravel. Sediment deposited at the mouths of streams flowing into current seas. Prodeltaic silty-sandy sediments might be locally observed in this unitStratified and generally well-sorted sand, sandy silt, gravelly sand and gravel deposited in shallow water during the pleni-marine phase and during land emergence. Shows a surface generally marked by coastal shorelines and nearshore bars, locally reworked by wind action. When associated with land emergence facies, this unit usually forms a thin veneer resting on deep-water sedimentMassive, laminated or stratified, grey to dark grey clayey silt and silty clay, locally including rythmites. Sediment deposited mainly by settling in the deeper depressions of current marine basinsSediment deposited in a current sea or ocean, but whose exact formation processes could not be determinedGenerally massive or slightly stratified silt and sandy silt. Sediment deposited in intertidal or subtidal zones into sheltered bays or postglacial sea arms, generally near large deltaic complexesStratified and well-sorted sand, gravelly sand and gravel. Sediment deposited at the mouths of streams flowing into post-glacial seas. Locally includes prodeltaic silty-sandy sedimentsStratified and generally well-sorted sand, sandy silt, gravelly sand and gravel. Sediment deposited in shallow water whose surface is generally marked by coastal or prelittoral shorelines, locally reworked by wind actionMassive, laminated or stratified, grey to dark clayey silt and silty clay, locally including rhythmites. Sediment deposited mainly by settling in the deeper depressions of the glaciomarine basinsSediment deposited in a postglacial sea (Champlain, Tyrell, Goldwaith, Iberville or Laflamme sea), but whose exact formation processes could not be determinedSand, silty sand, sandy gravel and boulders, deposited at the mouth of streams flowing into glacial lakes. Shows a flat surface generally marked by abandoned channels, and locally reworked by wind actionSand, silty sand, sandy gravel and boulders, deposited along the shores and within the glacial lake. Shows a surface generally marked by coastal and prelittoral shorelines, and locally reworked by wind actionGenerally laminated silt and clay forming locally rythmites or varves, and deposited in the deeper depressions of the glaciolacustrine basinsSediment deposited in a glaciolacustrine water plan, but whose exact formation processes could not be determinedSand, gravel and boulders organized in normal bedding sequences with finer particles generally situated further away from the glacial margin. The surface is characterized by flat-top ridges and outwash plains showing numerous shallow and sinuous channelsSand, silty sand and gravel deposited in relatively shallow water at the outlet of subglacial or intra-glacial tunnels, generally in a glaciolacustrine or marine basin. Locally exposed under glaciolacustrine or glaciomarine sequences, in either sand pits, gravel pits or natural sectionsGenerally stratified sand and gravel. Sediment transported by meltwater and deposited at the front of the glacier in an undifferentiated environmentSand, gravel, boulders and diamictic sediment forming eskers, kames, kame-delta or morainic ridges. Forms areas with a generally hummocky surfaceGravel, sand, boulders and diamictic sediment, deposited within an interlobate moraine. Surface generally covered largely by a thin veneer of littoral, prelittoral or aeolian sedimentsTill, diamicton, boulders, sand and gravel, deposited at the front of the glacier and consisting of one or several ridges whose surface is generally hummocky, and the lateral continuity is variableGlaciofluvial sediment whose exact formation processes could not be determinedDiamicton whose superficial part has been reworked by waves and currents related to a postglacial lake and sea. Sediment whose thickness is generally greater than 1 m, locally fossiliferous and containing stratified or substratified sandy-gravel layersDiamicton whose superficial part has been reworked by waves and currents related to a postglacial lake and sea. Sediment thickness is generally less than 1 m. The surface is generally punctuated by outcrops, and the structure of the underlying bedrock can be seen on aerial photographsDiamicton with a matrix of sand and gravel, with boulders often visible at the surface, and whose fine particle content have been washed out by meltwater. Usually found along glaciofluvial corridors or in topographic depressionsDiamicton with a loose and washed matrix, related to slow melting of the glacier, and whose thickness is generally greater than 1 m. Surface generally characterized by numerous pebbles and bouldersDiamicton with a matrix of sand and gravel, poor in fines particules, with boulders often visible on the surface. Shows generally a hummocky topography without any particular orientation. Sediment deposited during ice ablation by stagnant or inactive ice massDiamicton with a generally coarse matrix and showing several sedimentary structures (convolute laminations, faults, lenses, stratified sand and gravel). Forms wavy crests that are regularly spaced and oriented transversely to the ice flow (Rogen or ribbed moraines). Sediment deposited by an ice sheet in a compressive regime where ice flow conditions are relatively slow. Commonly found in association with drumlins and other types of streamlined landformsDiamicton formed mainly of lodgement or ablation facies, and characterized by swarms of streamlined landforms (drumlins, crag-and-tail and other glacial lineations) oriented in the ice flow direction. Sediment deposited by a glacier in an extensive regime where ice flow conditions are generally fastDiamicton blanket cover consisting mainly of lodgement and ablation facies, and whose thickness is greater than 1 mDiamicton formed mainly of lodgement and ablation facies whose thickness is lower than 1 m. The surface is generally punctuated by outcrops and the structure of the underlying bedrock can be seen on aerial photographs. This unit occurs mainly in bedrock areasGlacial diamicton whose exact formation processes could not be determinedGlacial or interglacial quaternary unit deposited before the Late Wisconsinan, but whose exact formation processes could not be determinedWeathered sedimentary formation of various natures, preserved from glacial erosion or not covered by the Late Wisconsinian glaciersBoulder (predominantly frost-shattered) field formed on high plateaus and covering a mosaic of rock outcrops and oxidized till. Widespread presence of stone circles, mudboils and striated soils, and locally of erratics within a majority of boulders of local originRock outcrops occasionally presenting a thin cover of sediment ( less than 30 cm), and whose exact nature could not be determinedOutcrops formed of intrusive igneous rocksOutcrops formed of undeformed sedimentary and/or volcanic rocks, and generally subhorizontalOutcrops formed of deformed metasedimentary and/or metavolcanic rocksOutcrops formed of high-grade metamorphic rocks