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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).