Permafrost - Definition
Fossil pingo
Depressed area that is sometimes water filled and is formed because segregated ice in core of pingo has melted and ground has subsided
Rock glacier
Similar to an ice glacier but with more rock debris
Relief
Slope of permafrost can vary between north and south facing
Thermokarst
Uneven topography with depressions and small lakes caused by thawing of ice rich permafrost. Can produce features such as sink holes, thaw lakes, beaded streams and drunken forests
Talik
Unfrozen ground under permafrost
Ice wedges
V-shaped masses of vertically foliated ice. Cold winter ground contracts and cracks and then thawing of snow or train in the spring gets frozen in the cracks
Ground ice
All types of ice found underground
720m
Cameron Island has the thickest permafrost in Canada with
Sorted patterned ground
Flat areas, patterned ground occurs as polygons or circles b/c of the sorting of particles in soil or till
Frost heaving
Freezing of pore water causes an expansion of 9% and the surface will be heaved up slightly
Pingo ice
Freezing of water intruded under pressure. Largest and most spectacular permafrost feature
Peat plateaus
Frozen peat deposits occurring in unfrozen bogs
20, 50
Have that occurs due to the excess ice that forms during the growth of segregated ice can range from __ to __mm
Clay
Ice lenses do not form in grounds with low permeability such as
1, 5
Ice wedges may grow to as much as _m in width and _m in depth
Vegetation and snow
Insulation for permafrost
Active layer
Layer above permafrost table that thaws in the summer
1, 7
Palsas can rise _-_m above the surrounding land
Unsorted patterned ground
Patterns due to changes in vegetation, soil, cracks in the ground, or ice wedges below the surface
Permafrost
Perennially frozen ground having a temperature below 0 for at least two consecutive years
Palsa
Mounds of peat, often oval shaped. Contain segregated ice lenses
Patterned ground
Occurs in shapes such as nets, circle, or polygons
Differential heave of particles of various sizes
One of the ways that sorting occurs is by
60, 400
Pingo ice can range up to __m in height and ___m in diameter
Mini volcanoes
Pingo ice looks like
Permafrost table
Surface separating active layer and permafrost
Pore ice
The normal pore water that has frozen
Solifluction
When melting snow cause active layer to sag b/c of excess moisture
Ice lenses
When moisture, diffused within soil or rock, accumulates in a localized zone.
Excess water
When thawed ice lenses yield
Segregated ice
Where extra water has been drawn to the freezing front
