glacial movement and formation terms

Question 1

what’s basal slippage?
where does it occur?

Answer 1

• when the base of the glacier is at pressure melting point, so there is meltwater at the base of the glacier which acts as a lubricant allowing the glacier to move more rapidly
• occurs in temperate glaciers

Question 2

what’s regelation creep?
where does it occur?

Answer 2

• where ice deforms and flows due to pressure and temperature changes. When a glacier moves over a surface, the pressure from the weight of the ice can cause the ice at the base to melt slightly. This meltwater can then flow away, allowing the ice above to move into the space created. As the glacier continues to move, the ice that was melted can refreeze once the pressure is released. This process helps glaciers to flow and adapt to the underlying terrain, contributing to their overall movement and shape.

Question 3

what’s internal deformation?
in which type of glacier does it occur?

Answer 3

• occurs in both warm and cold based glacials

Question 4

what’s intergranular flow?
in which type of glacial does it occur ?

Answer 4

• when the individual ice crystals within a glacier orientate themselves in the direction of the glacial movement and slide over each other
• occurs in both warm and cold based glaciers

Question 5

what’s laminar flow?
in which type of glaciers does it occur?

Answer 5

• the movement of individual layers in a glacier
• occurs in both warm and cold based glaciers

Question 6

what’s pressure melting point (PMP)?

Answer 6

• it is the temperature at which ice begins to melt due to pressure exerted on it.
• ie as the thickness of the ice increases ,weight increases so, the pressure at the base of the glacier also increases. this pressure can lower the melting point of ice, so it still could melt at temperatures below 0°c

Question 7

how does the gradient of a slope affect the movement of a glacier?

Answer 7

•steeper gradient allows glaciers to move faster due to a greater gravitational pull
• a flatter gradient means there is less gravitational pull so the glacier moves more slowly.

Question 8

how does altitude affect the movement of a glacier? (3points)

Answer 8

• with increasing altitude, the temperature decreases, which leads to greater accumulation of snow and ice
• glaciers tend to have a steeper gradient at higher altitudes which can increase their movement due to gravity.
• The weight of the ice at higher altitudes creates pressure-induced basal melting so a layer of lubrication and therefore more movement.

Question 9

what is lithology?

Answer 9

• the physical properties of rock (eg it’s resistance)

Question 10

how does lithology affect the movement of a glacier?

Answer 10

• it influences bed topography. less resistant rocks (e.g. sandstone) are more likely to eroded and create deformations which may slow movement down.

• smooth rocks can reduce friction, allowing the glacier to move more quickly

Question 11

how does the size of a glacier affect its movement?

Answer 11

• Larger glaciers have more mass and therefore are heavier, resulting in greater basal pressure, which leads to increased melting and the formation of meltwater, reducing friction and allows the glacier to flow more easily.
• larger glaciers have more internal deformation due to their own weight, and gravity so may move quicker
• Smaller glaciers do not have enough pressure to create meltwater, so move slower

Question 12

what is a polar (cold based) glacier?

Answer 12

•a type of glacier found in polar regions or high altitude regions
• the ice is frozen to the bedrock, which means there is little to no meltwater at the base so minimal sliding and movement,.

Question 13

what is a temperate (warm based) glacier?

Answer 13

• glaciers that occur in alpine (mountainous) environments and have a layer of meltwater on their base.
• the ice melts more readily during summer temperatures and retreats further than polar glaciers

Question 14

what’s diagenesis?
how does it take place in ice?

Answer 14

• the processes taking place in sediment as it converts from sediment to rock
• snow falls, and overtime it becomes compressed and air is squeezed out. the névé turns into firn under the weight of the glacier. the firn keeps getting compressed, turning the firn into ice

Question 15

what’s névé?

Answer 15

• the uncompacted, granular snow that forms on the surface of a glacier, typically at higher elevations.

Question 16

what’s firn?

Answer 16

• a type of granular snow that forms when snow compacts over time and begins to transform into glacial ice.
• it is denser than fresh snow but not yet fully transformed into solid ice.

Question 17

what is a glacier?

Answer 17

• a large body of ice that flows downhill under the influence of gravity

Question 18

what is alimentation?

Answer 18

• the processes that contribute to the growth of a glacier, through the accumulation of snow and ice.

Question 19

what are niche glaciers?

Answer 19

• the smallest ice masses that are patches of ice found in hollows on a north facing mountain slope

Question 20

why do polar glaciers move slower then temperate glaciers?

Answer 20

• they are frozen to the bedrock
•polar glaciers are found in colder regions so the ice does not melt quickly
•usually lack basal meltwater, so a lack of lubrication resulting in slower movement.
•the ice in polar regions tends to be denser and less deformable, contributing to slower flow rates.

Answer: Polar glaciers move slower than temperate ones due to colder temperatures and lack of meltwater, resulting in more rigidity and less flow.

Question 21

why do temperate glaciers move faster than polar glaciers?

Answer 21

• they are found in warmer climates,
• they have a layer of meltwater at their base which acts as a lubricant, reducing friction and enabling the glacier to flow more rapidly.