Technology Advances in Four Landforms Flashcards
Pingos
What are they?
(Mackay, 1998)
Pingos can be defined as ‘perennial, intra permafrost, ice-cored hills, typically conical in shape, that can grow and persist only in a permafrost environment’.
Pingos
Where are pingos commonly found?
(AMAP, 2011).
In continuous and discontinuous permafrost regions that are characterised by a seasonally changing active layer.
Pingos
Pingos can be classified on the basis of origin (genesis) into what 3 types?
Hydrostatic (formerly ‘closed system’)
Hydraulic (formerly ‘open system’)
Polygenetic
Pingos
What two unique principals exist that allow pingos to form?
(Burr et al., 2009).
Water is densest at 4oC (why the bottom of lakes never freeze)
Water expands upon reaching 4oC
Pingos
What are hydraulic pingos?
Open system pingos that occur in areas of discontinuous permafrost where there are interspersed areas of permafrost (land frozen for at least 2 years) and talik.
Pingos
How do hydraulic pingos form?
The active layer continually freezes and melts year on year above the permafrost and talik.
Over winter, as the active layer freezes down, water can become trapped between this and the permafrost that surrounds it.
This promotes the growth of an ice lens which pushes the land up above it as it expands.
Water underneath the permafrost can move through the talik between the permafrost areas because of capillary action (the movement of water through the soil because of ) and hydraulic pressure.
This water migrates to the ice lens and freezes, swelling the ground above further.
Pingos
Hydraulic Pingos therefore require a long-term balance between three factors?
(French 2007):
- Water Pressure
- Overburden strength
- Rate of Freezing
Pingos
Technological advances…
Remote sensing techniques provide observations of the physical environment from instruments mounted on aircraft or satellites
Pingos
Example of pingos technological advances in use
(Samsonov et al., 2016)
Satellite Differential Interferometric Synthetic Aperture Radar (DInSAR) to describe the growth of a large, relatively young pingo in the Tuktoyaktuk Coastlands.
Pingos
Remote sensing methods, in particular those from space offer the following advantages:
Provides data that would not be obtainable using ground based methods.
They provide global information in regional detail.
They are repetitive and of uniform quality, allowing temporal patterns, including trends, to be discriminated.
They give near simultaneous measurements of many different parameters.
They can be delivered in near real time (within a few hours if required), allowing assimilation into operational environmental models.
Patterned ground
What are they?
Patterned ground is terrain exhibiting surface patterning, primarily in the form of circles, polygons, irregular networks, or stripes.
Patterned ground
What are the two types of patterned ground?
Two types are distinguished: sorted patterns delimited by alternating soil and clasts, and nonsorted patterns defined by microrelief or alternating vegetated and unvegetated ground.
Patterned ground
How are they formed?
Most patterns form through recurrent freezing and thawing of moist soil in periglacial environments.
Patterned ground
How do small sorted forms form?
Small sorted forms reflect separation of stony soil into fine and coarse domains by differential frost heave and/or differential needle-ice growth.
Patterned ground
How do larger sorted patterns form?
Larger sorted patterns are probably produced by a combination of differential (annual) frost heave and buoyancy-driven soil circulation during thaw.
Patterned ground
What’s a difference between large and small patterns?
Small sorted patterns reflect shallow soil freezing, but large sorted patterns are often associated with permafrost.
Patterned ground
Technological advances…
(Balme et al., 2010).
The high spatial resolution of HiRISE (a camera on board the Mars Reconnaissance Orbiter) has recently revealed the presence of sorted patterned ground (Figure 10.9) in the Western Elysium Basin.
(Wilson, 2010)
Helps us understand the recent and past distribution of ice in the shallow subsurface and provide clues about climate conditions.
Ice wedge polygons
What are they?
(Christiansen et al., 2016)
(Cable et al., 2016., Frost et al., 2018)
Ice-wedge polygons are archetypal polygonal patterns that are feasibly the most ubiquitous feature of ground ice in the top 2–3 metres of this permafrost, particularly in areas where the permafrost is shallow and the topography is flat.
Ice wedge polygons
How are they formed?
The thermal contraction theory of wedge growth, suggested by Leffingwell (1915., Gell, 1978), states that ice wedges are produced as an outcome of soil between cracks in the ice shrinking and enabling the infiltration of meltwater in spring (Fortier and Allard 2005., Opel et al., 2018).
This requires severe ground frost in winter, predominantly enabled via a combination of low ambient temperatures (at least -10oC) and a thin snow cover (Wolter et al., 2018).
An inclined freezing front penetrates fastest beneath these cracks, causing any coarser clasts to be “pulled up” due to thermal conductivity. Over centuries to millennia of repeating this process, it eventually leads to the growth of a wedge-shaped ice body as the soil above the ice is pushed up, forming ridges (Mackay 1984).
Ice wedge polygons
Ice wedge polygons are categorically divided into two types:
High and low-centre, based on their microrelief and their relationship with vegetation (Mackay 2000., Steedman, 2014).
Low-centre polygons are outlined by peaty elevated ridges, which reduce water flow, with an (often pond filled) depression in the polygon centre.
High-centre polygons, considered to be suggestive of earlier ice-wedge degradation (Mackay, 2000), are outlined by subsided troughs, which enable efficient drainage of water, overlying the ice wedges and have elevated centres (Steedman, 2014).
Ice wedge polygons
Technological advances…
(Templeton et al., 2016)
In this study we estimate the volume of ice wedge ice for large areas in the Canadian High Arctic through the use of high resolution satellite imagery and the improved capabilities of Geographic Information Systems (GIS).
Hot water drilling and Antarctica’s Filchner Ice Shelf
Who wrote the main paper on this…?
(Makinson and Anker, 2014).
Hot water drilling and Antarctica’s Filchner Ice Shelf
What is the technology?
Access subglacial environments beneath ice shelves in the polar regions.
These observations are central to characterising ice-ocean and ice-bed interactions and revealing recent ice history captured in subglacial sediments.
Hot water drilling and Antarctica’s Filchner Ice Shelf
What’s an example of a drill?
The current hot water drill (HWD) infrastructure for use in the Arctic and Antarctic consists of three independent drilling systems with depth capabilities of 800 m, 1000 m, and 2300 m.
For example, the 1000 m hot water drill system uses high pressure pumps to deliver 120 litres of water per minute down the drill hose.
Hot water drilling and Antarctica’s Filchner Ice Shelf
A variety of instruments can be lowered down these subglacial access holes to capture a wide range of data. These include:
Ocean profiling instruments for water mass properties
Water samples taken at discrete heights in the water column
Sediment cores from the ocean floor or beneath ground ice for ice sheet history
Sub-ice shelf moorings to capture long term oceanographic measurements
Ice column instruments for long term temperature and ice deformation measurements
Hot water drilling and Antarctica’s Filchner Ice Shelf
What is an ice shelf?
An ice shelf is a thick suspended platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface. Ice shelves are only found in Antarctica, Greenland, Canada, and the Russian Arctic.
Hot water drilling and Antarctica’s Filchner Ice Shelf
Why have they done it?
By drilling down deep, the team hopes to find out how long ago the Antarctic ice sheet last disappeared and how water and sediments may be nudging the ice toward the sea
