PERIGLACIAL LANDFORMS

I am sitting here with two GCSE texts books that talk about periglacial processes however find it interesting that neither mention periglacial landforms. As I have never studied this particular area of geography, with text books and even BBC Bitesize failing to make reference to these areas, it is clear that it is not a main area in the National Curriculum and therefore I’m left wondering to what extent I need to revise the area.

Even looking at the website available, there is little that covers periglacial landforms. With the use of the following link, I have managed to grasp what a few of these landforms are.

http://coolgeography.co.uk/A-level/AQA/Year%2012/Cold%20environs/Periglaciation/Periglacial%20landforms.htm

Ice wedges/Polygon pattern

Ice wedges – These are the cracks in the grounds surface that are formed when the active layer freezes, causing the soil layer to contract resulting in the formation of polygon patterns. When the frozen active layer melts the following summer, the cracks either close up or become filled with meltwater and debris. This repeated process over a series of years can lead to wedges becoming up to a metre wide and three metres deep.

Circle patterns

Patterned ground – These are the patterns in the ground formed from particular processes ground material has been subject to in periglacial areas. There are a range of different patterns, including:

·         Polygon patterns (mentioned above).

• ·         Circles – mounds that have dropped leaving finer sediments in the middle of the circle, with larger sediments on the outer-circle.

• ·         Steps – sometimes developed from circles and polygons that can be seen going downslope consisting of larger stones and vegetation.

• ·         Stripes – lines of stone, vegetation and/or soil that form from transitioning steps on slopes.

Collapsed pingo

Pingos – Mounds formed by ground being forced upwards from the freezing and expanding of upper ground layers (see previous post ‘ground water freezing’ for more info).

Links:

http://revisionworld.co.uk/a2-level-level-revision/geography/glacial-environments/periglacial-processes-landforms/ice-wedges

http://www.britannica.com/EBchecked/topic/234530/glacial-landform/49782/Permafrost-patterned-ground-solifluction-deposits-and-pingos