Fluvio-glacial features

Question 1

Kame

Answer 1

Mounds of poorly sorted sand and gravel. They form within circular holes (moulins) or fissures (crevasses) in the glacier. Subglacial meltwater streams bring water and sediment along the top of the glacier-this sediment will fill the moulins and crevasses, creating mounds (kames) or ridges, due to crevasse filling

Question 2

Kame terrace

Answer 2

Composed of sands and gravels, but form along sides of glacier rather than snout. As valley walls warm up in summer, the warm rocks helps to melt ice nearest to it, forming long depression or trough along which meltwater flows. Ice melting here builds up terraces of sediment between ice and valley side. Deposits become sorted.

Question 3

Esker

Answer 3

Long sinuous ridge of unstratified sand and gravel. Formed due to deposition in subglacial stream. Channel of stream restricted by ice walls, allowing the bed to build up-leaving behind a ridge

Question 4

Sandur

Answer 4

Plain formed of glacial sediments found at snout deposited by meltwater streams coming from glacier.
Material brought down valley by glacier. Picked up, transported, sorted and dropped by running water beyond snout position.
Coarsest material travels shortest distance and found near to glacier. Finer material such as clay is carried some distance across plain before deposition.
Meltwater loses energy further it travels from glacier
Deposits also vertically layered, reflecting seasonal flow of meltwater

Question 5

Kettle holes

Answer 5

Iceberg carving occurs at snout-block of dead ice becomes detached from glacier during ablation series.
Dead ice deposited on outwash plain and serve as zone of high friction
Any sediment contained within meltwater channel flowing down outwash plain will become deposited around the dead ice, eventually burying it. When the dead ice melts, subsidence occurs. Once deglaciated, the kettle holes may become infilled with meltwater forming a kettle lake.

Question 6

Varves

Answer 6

Sedimentary structure found at bottom of proglacial lakes and/or in water bodies found at fringes of glacier.
Two layers-coarser lighter layer deposited in summer and finer, darker layer deposited in winter.
Summer-air temps highest, rate of ablation high, greater volume of meltwater production.
Higher the meltwater discharge, higher the velocity and carrying capacity of streams is greater. High rate of flow produces layer of coarser sediment

Question 7

Meltwater channels

Answer 7

A braided channel is one that is divided into smaller channels by temporary islands known as eyots. Braided channels tend to form in rivers that have a significant amount of sediment where discharge readily fluctuates.