Physical Geography -Periglacial Landforms

Question 1

Periglacial environments

Answer 1

An area with permafrost

Question 2

Permafrost

Answer 2

Permanently frozen ground where soil temps have remained below 0C for at least 2 YEARS

Question 3

Continuous permafrost

Answer 3

Summers so cold that there is only a SUPERFICIAL SURFACE melting on the ground
Reach depth of 1500m
Mean annual temp of below - 5 C can be as low as -50C

Question 4

Discontinuous Permafrost

Answer 4

Found in slightly warmer areas so there are sections of PERMANENTLY FROZEN GROUND separated by SMALL POCKETS of UNFROZEN LGROUND. (Talik)
Mean temps between -1C and -5C

Question 5

Sporadic Permafrost

Answer 5

Found when mean ANNUAL TEMP IS BELOW 0 and Summer Temps reach above
ISOLATED POCKETS of PERMANENTLY FROZEN GROUND remain BELOW THE SURFACE

Question 6

Active Layer

Answer 6

Summer temps enough (sufficient ) to MELT the SURFACE LAYER OF PERMAFROST
this layer can be very MOBILE (free to move)
Varies in THICKNESS depending on LATITUDE AND VEGETATION COVER

Question 7

Talik

Answer 7

Any UNFROZEN material within the PERMAFROST ZONE

Question 8

Pingo definition

Answer 8

Rounded ICE-CORES HILLS than can be as high as 90m in height and 800m in Diameter
Grow at rates of a couple of cm/year

Question 9

Pingo Formation Summary

Answer 9

Formed through process of FROST HEAVE Freezing (which forms GROUND ICE)
Ocurrs either on DISCONTINUOUS PERMAFROST
or CONTINUOS PERMAFROST

Question 10

Types of Pingos

Answer 10

Open-System pingos
Closed-System pingos

Question 11

Open-system Pingos

Answer 11

Form on DISCONTINUOUS PERMAFROST
as TEMPS DECREASE it Promotes and INCREASES ARTESIAN PRESSURE.
causes MOISTURE in the ground to form ICE LENS and ADVANCING PERMAFROST RAISE The overlying surface material is forced UPWARDS into a MOUND of GROUNJD
If PRESSURE is too much Ground above ICE LENS can CRACK and EXPOSE ICE
when ice melts - forms a LAKE PINGO

Question 12

Closed System Pingos formation

Answer 12

Developed BENEATH LAKE BED where the supply of water is from IMMEDIATE LOCAL AREA - CONTINUOS PERMAFROST
LAKE WATER seeps into the GROUND BENEATH- forming TALIK
in WINTER PERIODS as TEMPS DECREASE HYDROSTATIC PRESSURE Increases-MOISTURE in SOIL FREEZES- FORMING ICE LENS
e PERMAFROST grows during Cold period GROUNDWATER beneath the lake is trapped by the PERMAFROST BELOW.
This causes SEDIMENT to bulge in UPWARD PINGO SHAPE

Question 13

Collapsing Pingos- Ognips

Answer 13

Pingos can rupture/collapse when temperatures rise and the ice core thaws.
When this happens the top of the dome collapse leaving a cicurlar depression known as an ognip