What causes patterned ground?
PERMAFROST AND PERIGLACIAL FEATURES | Patterned Ground Most patterns form through recurrent ground freezing and thawing and are initiated by differential (laterally nonuniform) frost heave. Small sorted forms are produced by shallow differential frost heave or needle-ice heave.
What is a patterned ground in geography?
The term patterned ground refers to a wide group of periglacial landforms showing more or less regular surface geometric patterning in the form of circles, polygons, irregular nets or stripes (e.g. Ballantyne, 2018. (2018). Periglacial geomorphology.
Where is patterned ground found?
It is typically found in remote regions of the Arctic, Antarctica, and the Outback in Australia, but is also found anywhere that freezing and thawing of soil alternate; patterned ground has also been observed in the hyper-arid Atacama Desert and on Mars.
What are frost polygons?
Definition. The surface expression of permafrost crosscut by integrated/intersecting polygonized fractures (formed by means of thermal-contraction) that are filled with frozen water, i.e., ice wedges.
What is an Ognip?
When temperatures warm, the ice supporting the pingo melts. If it all melts the pingo can collapse, leaving a massive hole – playfully called an “ognip”. This may be what happened in Siberia. Such holes may become more common as the world’s pingos melt.
What are periglacial landforms?
A periglacial landform is a feature resulting from the action of intense frost, often combined with the presence of permafrost. Periglacial landforms are restricted to areas that experience cold but essentially nonglacial climates.
What is a periglacial landscape?
Periglacial environments are areas where landforms and geomorphic processes reflect the cumulative effects of cold subfreezing temperatures, cyclic freezing and thawing of sediments, and the volumetric expansion of soil moisture as it freezes. From: Past Glacial Environments (Second Edition), 2018.
What are Glaciofluvial landforms?
Glaciofluvial landforms are landforms created by the action of glacier meltwater. They can be erosional, or depositional landforms, and can form underneath, on top of, in front of, and around the edges of former glaciers.
What is ground ice?
a general term referring to all types of ice contained in freezing and frozen ground. frozen ground or permafrost.
What is an ice-wedge polygon?
What does a pingo look like?
pingo, dome-shaped hill formed in a permafrost area when the pressure of freezing groundwater pushes up a layer of frozen ground. Pingos may be up to 90 metres (300 feet) high and more than 800 metres (0.5 mile) across and are usually circular or oval-shaped.
What does pingo look like?
What is a pingo landform?
Pingos are ice-cored hills that form in recently drained lakes. The unfrozen ground directly beneath the lake, called “talik,” is surrounded by permanently frozen ground called permafrost. After the lake drains and the water-saturated sediment at the bottom of the lake bed becomes exposed, its surface begins to freeze.
What is an esker in geography?
esker, also spelled eskar, or eschar, a long, narrow, winding ridge composed of stratified sand and gravel deposited by a subglacial or englacial meltwater stream.
Can you melt permafrost?
As Earth’s climate warms, the permafrost is thawing. That means the ice inside the permafrost melts, leaving behind water and soil. Thawing permafrost can have dramatic impacts on our planet and the things living on it.
What is a Pingo landform?
What is Hydrolaccolith?
hydrolaccolith (plural hydrolaccoliths) (geology) A frost mound that has a core of ice and resembles a laccolith in cross-section.
What is a drumlin in geography?
Drumlins are oval-shaped hills, largely composed of glacial drift, formed beneath a glacier or ice sheet and aligned in the direction of ice flow.