Draw a River Regime for a mountain glacier in the

Canadian Rockies

How would Glacial and Glaciofluvial deposits differ?

Glacial Till

Fluvioglacial outwash deposit

Glacial Deposits Fluvio-glacial Deposits (includes deposits once deposited by ice and re-deposited by meltwater)

Unstratified (difficult to identify layers)

Stratified (vertical layering due to seasonal variations in sediment accumulation)

Unsorted (random sorting as ice melts and deposits material regardless of size)

Sorted - larger rocks and boulders are deposited first as the meltwater looses energy.

Material is angular, from physical weathering and erosion (unaffected by water) and various shapes and sizes (boulders - rock flour)

Material is smooth and rounded (due to attrition), it is sorted and graded.

Varves, AlbertaAthabasca River

Glacial lake varves, north side of the Athabasca River, Alberta, 1966.This photograph shows glacial lake varves lying on glacial till. The till is composed of rocks in a gravel, silt, clay, and sand matrix. It was deposited at the base of the Laurentide Ice Sheet during the Wisconsinan (23 000 to 10 000 years before present). Once the glacier had retreated (melted) to a point further east, glacial Lake Leduc occupied this section of the valley, and the varves were deposited in this lake. Glacial Lake Leduc is part of a sequence of lakes that covered north central Alberta. The varves represent a year of the lake’s history: a pale coloured layer of silty sand deposited in summer, and a dark clay layer deposited in winter. During the summer, more water and sediments flowed into the glacial lake; therefore, the coarse, heavy material, like sand and silt, was deposited on the lake bottom. During the winter, the lake was covered with ice and little, or no, sediment flowed into the lake, allowing clay, very fine silt, and organic particles to settle to the bottom. Varves afford geologists an opportunity to calculate the age of the lake, similar to counting the rings of a tree trunk. At the bottom of the lakebed, near the till, the varves are faint and wide; near the top, they are defined and thin. This difference is related to the depth of the glacial lake. As the lake became deeper, the sediment source grew further away; therefore, less sediment settled during each season.

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Kame Deltas

Kettle holes

Sandur

Glaciers deliver large quantities of unsorted, unstratified and mixed size/shape material to the snout of the glacier, where it is dumped or

deposited as moraine

The end result is a broad, flat relief feature with many braided streams, known as an outwash plain.

Eskers

Varves

Annotate the Image with full explanations of how Varves, Kames, eskers and outwash plains form.

Research: How could Fluvio glacial features affect human activity?