Glaciolacustrine deposits

Glaciolacustrine deposits

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Sediments deposited into lakes that have come from glaciers are called glaciolacustrine deposits. These lakes include ice margin lakes or other types formed from glacial erosion or deposition. Sediments in the bedload and suspended load are carried into lakes and deposited. The bedload is deposited at the lake margin while the suspended load is deposited all over the lake.

Glaciolacustrine Bedload Deposits


Sediments carried in the bedload of a stream, mostly sands and gravels, are deposited in deltas
River delta
A delta is a landform that is formed at the mouth of a river where that river flows into an ocean, sea, estuary, lake, reservoir, flat arid area, or another river. Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river...

 that form at the edges of lakes. These deposits will only be found near the edges of the lake and not in the middle.

Glaciolacustrine Suspended Deposits


Sediments that are carried in the suspended load of a stream, commonly silts and clays, are transported into the lake in suspension or by currents along the lake floor. These are the principle deposits during the winter because of lack of melting of the glacier
Glacier
A glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...

 so the stream has a reduced discharge
Discharge (hydrology)
In hydrology, discharge is the volume rate of water flow, including any suspended solids , dissolved chemical species and/or biologic material , which is transported through a given cross-sectional area...

 therefore carrying less coarse material. These sediments normally consist of fine-grained rhythmites that are laid down in layers known as varve
Varve
A varve is an annual layer of sediment or sedimentary rock.The word 'varve' is derived from the Swedish word varv whose meanings and connotations include 'revolution', 'in layers', and 'circle'. The term first appeared as Hvarfig lera on the first map produced by the Geological Survey of Sweden in...

s or varvites. A varve
Varve
A varve is an annual layer of sediment or sedimentary rock.The word 'varve' is derived from the Swedish word varv whose meanings and connotations include 'revolution', 'in layers', and 'circle'. The term first appeared as Hvarfig lera on the first map produced by the Geological Survey of Sweden in...

represent an annual deposition of materials and in this case that being silt/clay. Sedimentation in deltas also occurs in rhythmic patterns as in the lake deposits, but they are thicker and contain coarse-grained materials instead of just silt and clay. As the varves get closer to the shoreline the clay layer will stay relatively the same thickness, but there will be an increase in thickness of the silt layer.