glacio- fluvial depositions

Question 1

when are glacio fluvial processes are most evident?

Answer 1

When glacial periods end and when temperatures rise

Question 2

what is iceland jokulhaups?

Answer 2

glacial outbursts caused by geothermal activity beneath glaciers caused melting→ lead to more than 200,000 tonnes of sediment deposited in valleys.

Question 3

what are glacio - fluvial landforms?

Answer 3

Are created by meltwater from glaciers, largely through deposition but can be through erosion.

Question 4

what is a subglacial stream?

Answer 4

They are streams that flow beneath a glacier which usually cuts into the ice above to form a tunnel.

Question 5

Why may the energy of meltwater change ( 4 points) ?

Answer 5

• seasonal variation
• diurnal variation
• rapid drainage of englacial chamber
• blocking of a meltwater channel by ice

Question 6

seasonal variation

Answer 6

loses energy in winter melts when the water in stream freezes so that discharges either are low or may cease altogether

Question 7

diurnal variation

Answer 7

due to daily variation in ablation

Question 8

Rapid drainage of englacial chamber

Answer 8

within the glacier a chamber of meltwater is rapidly drained → increasing velocity

Question 9

Blocking of meltwater channel by ice

Answer 9

reduces speed / loses ability to transport material.

Question 10

what does the Hjulstrom curve show?

Answer 10

Shows the relationship between river velocity ( y axis) and the size of the sediment (x axis)

Shows the relationship between river velocity and competence ( ability of a stream to transport individual particles of a given size)

Question 11

As the sediment increases in size the :

Answer 11

• more deposition will occur more easily
• increased velocity required to transport material
• erosion requires increased energy within the water

Question 12

what are glacio- fluvial deposits called?

Answer 12

outwash

Question 13

characteristics of outwash

Answer 13

• smaller
• smooth and round
• sorted
• stratified vertically

Question 14

characteristics of outwash
smaller

Answer 14

as meltwater streams are less energy than glaciers

Question 15

characteristics of outwash
smooth and round

Answer 15

process of water and erosional attrition

Question 16

characteristics of outwash
sorted

Answer 16

horizontally largest found in the valley and finer material further down the valley as velocity falls

Question 17

characteristics of outwash
stratified vertically

Answer 17

vertically anually laid sediment following seasonal variations

Question 18

How do characteristics of outwash vary?

Answer 18

Will vary from distance from the ice front in a series of zones

Question 19

what are the three zones?

Answer 19

1. proximal zone
2. medial zone
3. distal zone

Question 20

Proximal zone

Answer 20

• larger particles
• reflecting high discharge of meltwater from the glacier
• As both direct glacial and meltwater deposition occurs * glacial till interbedded with glacio fluvial deposits

Question 21

Medial zone

Answer 21

• not as coarse
• clasts are more rounded
• reflecting increase in transportation
• meltwater discharges are highly seasonally and daily variable

Question 22

Distal zone

Answer 22

• better sorted
• more rounded
• only finer particles are transported this far - energy levels had fallen