Glaciated Landscape Development Flashcards
What is a corrie and how is it formed? (E)
- Armchair-shaped rock basin found on the N and E slopes of mountains
- Snow is compacted in a hollow and erodes the hollow through nivation, abrasion, plucking and rotational slip
What is an aréte and how is it formed? (E)
- Steep knife-edged ridge formed between two corries
- The backward erosion of two conjoined corries through plucking forms steep back walls
What is a pyramidal peak and how is it formed? (E)
- Angular, sharply-pointed summit
- Three or more corries meet back-to-back and their back walls are eroded by plucking
What is a glacial trough and how is it formed? (E)
- Straight, wide U-shaped valley
- Glaciers move over existing V-shaped river valleys and cause glacial scouring due to their massive erosive power
What is a hanging valley and how is it formed? (E)
- Small tributary U-shaped valley
- The tributary valley glacier does not have a large enough erosive power to erode to the valley floor and is left hanging, often with a waterfall
What is a truncated spur and how is it formed? (E)
- Ridge that descends to the valley floor found in a glacial trough
- Glaciers erode interlocking spurs from an existing river valley and remove areas of land
What is a roche moutonée and how is it formed? (E)
- A rock mound with a smooth stoss side and a jagged lee side
- Plucking and abrasion erode areas of resistant rock as a glacier moves over it
What is a Bergschrund and how is formed? (E)
- A large crevasse in a glaciated landscape
- A glacier moves and separates from the back wall of a corrie
What is a ribbon lake and how is it formed? (E)
- A lake formed within a glacial trough
- A glacier moves over alternating bands of soft and hard rock, eroding the soft rock at a higher rate and leaving a rock basin which fills with rainwater
What is a fjord and how is it formed? (E)
- Steep coastal cliff in a glaciated landscape
- Glacial erosion occurs below sea level and sea water fills the valley floor as the glacier retreats
What is a drumlin and how is it formed? (D)
- A smooth, elongated mound of unsorted till with a steep stoss side and a gentle sloping lee side
- A glacier slows down as it moves over a resistant obstacle and causes deposition behind it
What is an erratic and how is it formed? (D)
- A large boulder in a glaciated landscape
- Carried by the glacier and deposited in an area of completely different geology
What is a till plain and how is it formed? (D)
- A large expanse of flat relief covered in glacial sediment
- Formed as a large section of ice detaches from a glacier and melts, causing deposition of unsorted till
What is a moraine? (D)
A ridge of deposited glacial sediment.
What are the five types of moraine?
- Lateral
- Medial
- Terminal
- Recessional
- Push
What is a lateral moraine? (D)
A moraine found at the side of a glacier formed by freeze-thaw weathering on the valley sides providing debris to the glacier.
What is a medial moraine? (D)
A moraine found between two glaciers formed through the merging of two lateral moraines.
What is a terminal moraine? (D)
A moraine that is deposited at the maximum advance of a glacier.
What is a recessional moraine? (D)
A moraine found behind a terminal moraine formed by deposition during a temporary standstill in glacial retreat.
What is a push moraine? (D)
A moraine with sediment that is tilted upwards formed during temporary glacial advance as sediment is pushed into an existing terminal moraine.
What is a meltwater channel? (F)
Meltwater streams within a glacier which deposit material when there is a decrease in discharge.
What is a kame and how is it formed? (F)
- A mound of partially sorted sand and gravel formed at the side of a glacier
- A collection of material in a supraglacial hollow is left on the valley floor when the glacier melts
What is a kame terrace and how is it formed?
- A relatively flat, elongated deposit of fluvioglacial sediment
- Formed when multiple kames occur in the same area
What is an esker and how is it formed? (F)
- A long ridge of stratified sand and gravel
- Sediment in meltwater channels is deposited in the direction of the glacier’s flow as the glacier melts
What is an outwash plain and how is it formed? (F)
- A large expanse of fluvioglacial deposits infront of a glacial snout
- Meltwater channels lose hydrostatic pressure as it leaves the snout, causing deposition
What are braided channels and how are they formed? (F)
- Meltwater streams that cross each other on an outwash plain
- Streams try to find a more efficient route around the material deposited during low discharge which causes resistance
What is a kettle hole and how is it formed? (F)
- A depression found in an outwash plain
- Dead ice is left on the outwash plain as ice calving breaks it off from the glacial snout, before being buried in fluvioglacial sediment and melting
What is patterned ground and how is it formed? (P)
- Geometric patterned ground found in periglacial environments
- Frost heave causes the upward movement of stones to the soil surface which then move sideways due to the slope
What is an ice wedge and how is it formed? (P)
- Narrow crevasse in the upper layers of the ground
- Water enters cracks in the frozen soil and expands on freezing before repeating, widening the crack
What is an open-system pingo and how is it formed? (P)
- Dome-shaped mound of earth found in areas of discontinuous permafrost
- Water moves through unfrozen ground, known as talik, forming an expanding ice lens which pushes upwards
What is a closed-system pingo and how is it formed? (P)
- Dome-shaped mound of earth found in areas of continuous permafrost
- An ice lens forms underneath a draining lake in a layer of talik, causing frost heave and upward expansion
What is a blockfield and how is it formed? (P)
- A large expanse of angular boulders
- Freeze-thaw weathering forms these boulders in-situ
What is a solifluction lobe and how is it formed? (P)
- A tongue-shaped lobe of soil found on slopes
- Active layer becomes waterlogged in summer which saturates the soil, allowing it to slowly move downslope
What is a terracette and how is it formed? (P)
- Narrow steps of land with a small tread
- Frost heave pushes the ground upwards, however vegetation prevents soil slumping (solifluction)
What is a thermokarst and how is it formed? (P)
- An expanse of land characterised by depressions filled with meltwater
- Caused by the melting and collapse of permafrost
