Glaciation

Question 1

Pleistocene

Answer 1

The epoch (period) that dated from 2 million years ago to 11,500 years, the early part of the quaternary which included the most recent ice age.

Question 2

What is the Pleistocene regarded as?

Answer 2

a single ice age - but there were multiple periods of glacial (stadial) and interglacial (interstadial) conditions - periods fluctuated.

Question 3

Long term causes of climate change:

Answer 3

The Milankovitch cycles:

• Eccentricity of the orbit
• axial tilt
• wobble

Question 4

Short term causes of climate change:

Answer 4

• solar forcing (sunspots)

- volcanic eruption

Question 5

Eccentricity of the orbit (orbital stretch) + what it causes

Answer 5

• when the orbit of the earth changes from nearly circular to elliptical over a period of 100,000 years - changes the amount of radiation the earth receives (circular = colder periods, elliptical = warmer periods)

Question 6

Axial tilt

Answer 6

• when the tilt of the earth varies from 21.8 - 24.4 degrees over 41,000 year cycle.
• The greater the tilt is towards the Sun, the more solar energy the poles recieve = favours interglacial periods (+ favours glacial when tilting away.

Question 7

Wobble

Answer 7

• wobbles in a circular motion + changes the point in the year where the Earth is closest to the Sun (axial precession) over a 21,000 year cycle - causes changes to when different seasons occur.

Question 8

Holocene (interglacial)

Answer 8

is the period we now live in

Question 9

Quaternary period

Answer 9

Started 2 million years ago and is what we are in today.

Question 10

What are the milankovitch cycles sustained by?

Answer 10

Climate feedback mechanisms - positive and negative feedback.

Question 11

Positive feedback

Answer 11

AMPLIFY change - e.g. cold temp is sustained by increased snow cover (increases surface albedo.)

Question 12

Negative feedback

Answer 12

DIMINISH change - e.g. increase in temp = increase in evaporation of ocean surface water = increase in low thick cloud cover - this counteracts warming as it reflects solar energy to space.

Question 13

what is solar forcing? what happens when there is a lot of it? + background info

Answer 13

The more sunspots on the Sun’s surface, the more solar energy will be emitted, the earths global temp will increase.

• 20% of the 20th century warming was caused by solar output variation.
• But - total variation in solar radiation caused by sunspots is only 0.1% - solar forcing is a contributing factor to climate change.

Question 14

Effects of volcanic eruptions

Answer 14

• can increase and decrease global temp
• volcanoes with high VEI eject huge volumes of ash, sulphuric dioxide, CO2, and water vapour - which high level winds distribute around the earth.
  Ash and sulphuric acid aerosols reflect solar radiation back into space, causing a global cooling effect, which can last from months to years.
  CO2 - enhance greenhouse effect + has a warming effect.

Question 15

Cryosphere

Answer 15

The parts of the Earth’s crust and atmosphere subject to temps below 0 for at least part of the year.

Question 16

Ice sheet

Answer 16

a broad, thick sheet of ice covering an extensive area for a long period of time.

Question 17

Ice cap

Answer 17

Dome shaped mass of glacier ice found in upland areas (smaller version of an ice sheet.)

Question 18

Ice field

Answer 18

Thinner ice covering an upland area (formed by ice caps connecting.)

Question 19

Cirque valley

Answer 19

Smaller glacier in a hollow of a mountain side.

Question 20

Valley glaciers

Answer 20

Glacier confined between valley walls.

Question 21

Permafrost

Answer 21

soil and rock that remains frozen if temps do not exceed 0 in the summer months for at least 2 consecutive years.

Question 22

Talik

Answer 22

soil within permafrost (unfrozen ground)

Question 23

The types of permafrost + explanation of what they are.

Answer 23

• Continuous - continuous sheet of frozen ice
• Discontinuous - areas of permafrost interspersed with talik.
  Sporadic - larger area of talik vs permafrost

Question 24

Active layer

Answer 24

The top layer of soil in permafrost environments that thaws during summer (producing meltwater which saturates upper layer due to permafrost being impermeable = meltwater causes distinctive periglacial landscapes to be created!) And freezes during winter.

Question 25

Name all the periglacial processes:

Answer 25

• Nivation
• Frost heave
• freeze thaw weathering
• solifluction
• meltwater erosion
• wind action

Question 26

Nivation

Answer 26

is a combinaton of processes that weakens and erodes the ground beneath a snow patch, which forms a nivation hollow. - these processes include freeze thaw weathering, solifluction and meltwater erosion.

Question 27

Frost heave

Answer 27

The freezing and expansion of soil water causes the dislocation of soil and rocks. As the ground freezes, large stones become chilled faster than the soil, the water below the stone’s freezes + expands, causing the stones to be pushed upwards + forming small domes on the ground surface.

Question 28

Freeze-thaw weathering

Answer 28

when water seeps into the cracks of rocks and then freezes + expands (up to 10%) weakening the rock through repeated freeze-thaw cycles, eventually causing the chunks of rock to break away.

Question 29

Solifluction

Answer 29

is the slow downhill flow of saturated soil – the active layer provides enough water to allow flow to occur, this forms solifluction lobes.

Question 30

Wind action

Answer 30

• Due to lack of vegetation and plentiful loose material, allows strong cold winds to pick up large amounts of material and redeposit it far away from its source as loess E.g., in the Mississippi-Missouri Valley, USA.

Question 31

Meltwater erosion

Answer 31

During the short summer, thawing creates meltwater, which erodes river channels, refreezing at the onset of winter causes a reduction in discharge and sediment deposition in the channel.

Question 32

Where are periglacial landscapes found?

Answer 32

at the fringes of polar glacial environments + dominated by permafrost.

Question 33

simple solar forcing (changes in solar output) effects + how long effects last.

Answer 33

The changes in the amount of energy emitted from the sun due to the number + density of sunspots - 11 year cycle + can last 100 - 150 years.

Question 34

Simple volcanic eruptions effects + how long effects last.

Answer 34

eruptions with high VEI = eject huge amounts of ash sulfur dioxide + CO2 into atmosphere = cooler temps globally as ash reflects solar radiation back into space - lasts 1 - 2 years.

Question 35

Ablation

Answer 35

The output of snow and ice from a glacier by melting, calving of icebergs, sublimation or evaporation.

Question 36

Plucking

Answer 36

Occurs where rocks are weakened or well-jointed and where there is meltwater present at the base of the glacier. The meltwater penetrates into joints and around obstacles then freezes onto the rock. As the ice moved, it exerts an immense pulling force onto the attached rock, which is plucked from its position. Also known as quarrying.

Question 37

Entrainment

Answer 37

The process by which surface sediment is incorporated into a fluid flows (e.g. ice) as part of the process of erosion.

Question 38

Supraglacial

Answer 38

Debris transported on the surface of the glacier

Question 39

subglacial

Answer 39

debris transported beneath the glacier

Question 40

Englacial

Answer 40

Debris transported inside the glacier.