Glaciated Landscapes And Change EQ1

Question 1

How old is the earth, and what to states does it fluctuate between?

Answer 1

• The Earth is around 4.6 billion years old
• The climate has fluctuated between two dominant states, the greenhouse earth and the icehouse earth
• We are currently in an icehouse earth in an interglacial period

Question 2

What has the earth been like over the last 2 million years?

Answer 2

• Temperatures on earth have fluctuated considerably
• This fluctuation has led to cold periods (glacial) and warm periods (interglacial)
• In the last 1million years there may have been up to ten glacial periods, each separated by interglacial periods

Question 3

When was the most recent ice age?

Answer 3

• The Most recent is the quaternary ice age
• It started 2.6 million years ago and extends to the current day
• It is divided into two epochs, the Pleistocene and the Holocene

Question 4

What were the main characteristics of the Pleistocene?

Answer 4

-It lasted until approximately 12,000 years ago
-It wasn’t just a single ice age, as fluctuating temperatures caused numerous ice advances and retreats
-The extent to which ice advanced during each glacial period was different
-The are fluctuation within each major glacial:
Periods of short advance are known as Stadials
Periods of warmer retreat are known as interstadial

Question 5

How do Milankovich cycles cause climate change over a long period?

Answer 5

• The 100,000 year oscillation cycles combine to decrease the earth’s temperature and increase the earth’s ice volumes
• However, The combined cycles only reduce the earth’s temperature by 0.5-1°C
• Large scale climate change occurs due to climate feedback.
  
  • Increase snow and ice from the earth’s decreased temperature will increase the earth’s albedo effect which in turn will reduce the earth’s temperature and increase snow and ice cover etc, etc

Question 6

How do plate tectonics cause climate change over a long period of time?

Answer 6

• 3 million years ago, the North and South American continents collided which cut off the Gulf Stream from flowing round the equator
• The Gulf Stream was then forced to flow towards the Northern Hemisphere, providing these regions with lots more evaporated water, increasing snowfall in the regions
• This build up of snow and ice triggered a global cooling which led us into the current ice age

Question 7

How are sun spots a short term cause of climate change?

Answer 7

• Sun spots occur when the sun gives off more energy, an they occur over an 11 year cycle
• If There are more sun spots then there is an increase in the earth’s temperature, if there are fewer then there is a decrease in the earth’s temperature

Question 8

How do volcanic eruptions cause short term climate change?

Answer 8

• When volcanoes erupt they spew large amounts of ash into the atmosphere
• This ash blocks the sun’s rays and cools the earth down. However, the ash only stays in the atmosphere for a few months
• The most significant cause of cooling comes from sulphur aerosoles, which are formed from sulphur dioxide, which stay in the atmosphere for up to 3 years and reflect rays for that long

Question 9

What was the cause of the Loch Lomond stadial?

Answer 9

• The Loch Lomond stadial was caused between 12,500 and 11,500 years ago when temperatures plummeted by 6-7°c
• This caused glaciers to re advance in many parts of the world, most notably the Lake District
• Many believe it could have been caused by the blocking of the Gulf Stream

Question 10

What was the cause of the Little Ice Age?

Answer 10

-It is believed that the Little Ice age was caused by both increased volcanic output and decreased solar/sunspot activity. These factors would have combined and resulted in widespread global cooling

Question 11

What is the cryosphere?

Answer 11

The frozen part of the Earth’s hydrological cycle, made up of ice sheets, glaciers, ice caps as well as many areas of snow and permafrost and frozen rivers, lakes and oceans

Question 12

Why is the cryosphere important?

Answer 12

• The cryosphere stores masses of freshwater
• The cryosphere contributes massively to the albedo effect which in turn regulates the earth’s temperature and mitigate temperature increases
• Scientists also use the polar regions to conduct important research into climate change, as the polar regions are the most sensitive to climate change

Question 13

What are warm based glaciers?

Answer 13

• Glaciers that occur in high-altitude areas outside of the polar regions e.g. the Alps
• In these glaciers the base is above melting point, either from friction or geothermal heat, and so the meltwater created acts as a lubricant, causing the glacier to move easily
• Ice at the top of the glacier also melts above 0° and so gives the glacier more lubricant causing it to move more and more
• The high levels of movement from the glacier results in high levels of erosion and causes lots of debris to be entrained in the base

Question 14

What are cold based glaciers?

Answer 14

• These glaciers occur at high latitude areas such as Antarctica/Greenland
• The base of the glaciers is well below freezing, resulting in no melting
• The lack of melting causes the glacier to stick to The Valley base, resulting in little to no movement
• This lack of movement results in no erosion from the glacier and means that no debris is collected at the base of the glacier

Question 15

What are Ice sheets?

Answer 15

• Unconstrained
• Large masses of ice (>50,000km3) that have a significant thickness and bury whole landscapes except the highest mountains
• The best example of ice sheets are in the Antarctic

Question 16

What are Ice shelfs?

Answer 16

Ice sheets that extend out to sea

Question 17

What are Ice caps?

Answer 17

• Unconstrained
• Dome-shaped ice masses that cover mountain peaks and plateau areas
• They are <50,000km3

Question 18

What are Ice fields?

Answer 18

Ice caps that are typically smaller and constrained by the surrounding land

Question 19

What are valley glaciers?

Answer 19

Rivers of ice that are constrained and contained within steep sided U shaped valleys

Question 20

What are Piedmont glaciers?

Answer 20

• Constrained

- Valley glaciers that spread out on flat plains and form large lobes after leaving a narrow mountain valley

Question 21

What are cirque glaciers?

Answer 21

Constrained glaciers that form in armchair shaped cirques/carries

Question 22

What was ice coverage like in the Pleistocene compared to the present day?

Answer 22

• At the Pleistocene maximum, ice coverage was more than 3x greater than it was now
• Ice coverage in Greenland and the Arctic are at similar levels to the Pleistocene period
• Ice coverage in North America and Scandinavia was much greater in the Pleistocene than it is now

Question 23

What erosionad evidence is there of the Pleistocene in Britain today?

Answer 23

• Glacial landforms e.g. carries, U-shaped valleys, Crag and tail landscapes etc etc
• This evidence and be found in the Cairngorms, Snowdonia and the Lake District

Question 24

What meltwater evidence is there of the Pleistocene in the U.K.?

Answer 24

• Meltwater channels (Newtandale N.Yorkshire)
• Glacial till (the holderness coast)
• Eskens (e.g. blackeney, Norfolk)

Question 25

What depositional evidence of the Pleistocene is there in the U.K.?

Answer 25

• Drumlins (e.g. The Valley of Eden, Cumbria)
• Erratics (e.g. the border state in the Lake District)
• Moraines (e.g. in the Cairngorms)

Question 26

What is permafrost?

Answer 26

Solid rock that remains frozen as long as temperatures do not exceed 0° in the summer months for at least two consecutive years

Question 27

What are the 4 main differences between continuous and discontinuous permafrost?

Answer 27

• Continuous occurs at higher latitudes (Above 65°)
• Continuous occurs at lower temperatures (Below -6°)
• Continuous is deeper
• Continuous has a thicker active layer

Question 28

Describe the process of frost heave

Answer 28

• Ice lenses are formed when water under rocks freeze when they come into contact with rapidly chilled rocks
• When the ground freezes ice expands and forces stones and rocks up to the surface. This is known as frost heave

Question 29

How does frost heave cause stone polygons?

Answer 29

• Smaller particles that are pushed to the surface may be removed by wind and meltwater leaving large stones on top marking out a polygonal patter
• Sloping ground can distort polygons as slopes gradually slide or roll downslope due to gravity, causing stone slopes instead
• If the incline is greater than 30° then patterned features can no longer occur and avalanches may occur

Question 30

Explain how ground contraction forms ice wedge polygons

Answer 30

• Ice wedges are downward tapering bodies of ice
• The re freezing of the active layer in the summer months causes the ground to contract
• Cracks open up on the surface, similar to cracks at the bottom of a dried up lake. In the summer these cracks fill with meltwater which often carries sediment into the crack
• This process continues over hundreds of years, until the cracks are widened up to 1m and deepened to up to 2-3m
• The cracking produces a pattern on the surface when viewed from above is similar to the polygons produced by frost heaving
• These features are therefor know as ice wedge polygons, and when they are filled with sediment they are known as ice wedge casts

Question 31

Explain two ways in which periglacial processes have contributed to upland landscapes. (Nivation hollows, aeolian action/meltwater erosion)

Answer 31

• Nivation is a number of processes that are active on the ground beneath a snow patch
• These processes include freeze-thaw weathering and summer meltwater moving debris
• These processes erode rock and carry them away from the upland area
• This process leaves behind patches of snow in upland areas which are known as Nivation hollows
• Another process is aeolian action and meltwater erosion
• In aeolian action, wind picks up fine sediment, due to a lack of vegetation, and deposits the sediment creating deposits known as loess
• Similarly, meltwater erosion erodes and transports sediment In spring and summer
• When deposited they create braided streams with multiple channels separated by islands of deposited materials