1. Lecture Ground Ice Definition Classification Summary Ice content
Genesis
Form
Process and Form
Summary

2. Ground Ice Ground Ice Often found in permafrost Definition Ice Content
Body of clear ice within frozen ground
Ice Content
Directly related to water content in a frozen conditions
ICE CONTENT = Wt. of Ice/Wt. of dried soil x 100%
Can’t usually go above porosity of the soil
Can get very stupid results
95/5 x 100= 1900 % Moisture Content

3. Excess Ice Content Excess Ice Content Relates to ice rich samples
Use volumetric measurements rather than weight measurements
Put 100 g of sample in a beaker
Water cannot fit into soil matrix
(-supernatent water)
H20
E.I.C.= 20%
100 cm3
* Upper limit to sample**

5. Important Storage Term: Gets Little Respect

6. Different Ways of Classifying Ground Ice
1) Genesis
2) Form
3) Examine Process and Form
1) Genesis:
Ice in sediment
While sediment is being laid down
After sediment is being laid down

7. Continued
If happening same time - SYNGENETIC ICE (does not happen very often-e.g. Siberia)
If happening after a climatic change – EPIGENETIC ICE (e.g. Canada)
Ground Ice - want to talk about excess ice content

8. > 2.5 cm < 2.5 cm N=Not Visible Vx= individual ice crystals or
B= Bonded
n= no excess ice
e=excess ice
F=friable, easy for it
to fall apart (dry sand,
little or no ice present)
Vx= individual ice crystals or
Inclusions
Vs= stratified or distinctly oriented
Ice formation (bands are right angle to heat flux)
Vc=coatings on large particles in the soils
VR= random, or irregularly formed ice
formations

9. Process Form Classification-Mackay, 1972
10 different kinds of ice
1) Open Cavity ice
Formed by sublimation of ice crystals directly from water vapour-crack
-2 Deg. C
Ground Surface
-15 Deg. C
-cooling of water vapour
….ice in crack due to
sublimation

10. 2) Single Vein Ice
Penetration of water into an open fissure (liquid form)-re-freezing of a single vein within the ground.
beginning of wedge ice

11. 3) Repeated Vein Ice=Wedge Ice
Cracking takes place repeatedly near vertical wedges
Tends to crack repeatedly at the same place….see vertical foliation

12. Epigenetic Ice Wedges

13. Ice Wedge, NWT

14. 4) Tension Crack Ice
Pressure-sometimes by other features (e.g. pingos)
5) Closed Cavity Ice-RARE
6) Epigenetic Segregated Ice
Movement toward a freezing plane
Freezing Plane
Movement of water from below
to freezing plane

15. Continued Pore water migration
Forms ice right behind the freezing plane
Temps. –0.1 to –0.2 Deg. C
Frozen fringe of soil
Buildup of Ice Layer

16. Continued
Freezing plane can remain stationary until we build up a thicker ice lense
Ice lense-mm’s to 10’s of cm thick
In course particles
Freezing plane into coarse particles pushes water down and up
Sands and gravels

17. Continued Pore Water Expulsion
OCCURS-no where for the excess water to go-has to go into the unfrozen soil
This is very important for pingo formation

19. Aggradational Ice
Segregated Ice
Ground Ice Slump
ICE
MUDFLOW

20. Continued Mudflow will dry up- 1 to 2 m deep
Permafrost will grade into the bottom of it
Porewater movement to the base of the mudflow
Lenses of ice in the new permafrost
-old mudflow
-aggregated,
segregated ice

21. 8) Intrusive Sill Ice (Injection Ice)
Water is injected into frozen soil
f’table
Injection of water,
Gives rise to an
Ice body
p’table

22. Intrusive Pingo Ice Pingos are ice cored hills
> 60 cm-up to 300 m in diameter
Some cores are almost pure ice

24. 10) Pore Ice Bonding ice which holds soil grains together
Pore ice fill spaces, to get water, you must have coatings on particles
Must have segregated ice to get water
Pore Ice fills spaces

25. Proportions of Ground Ice
Alaska North Slope-CREEL-Total vol: 1, 500 km3
71% of ground ice was pore ice
Greatest conc. of ice near the top of the permafrost table.
50%
Active Layer
-below active layer, get wedge ice, therefore
lots of ice

26. Continued Top portion of p’frost is rather warm
Water vapour and liquid water can penetrate
Year after year water trickles down
……..going to have an ice rich layer on top of the permafrost

27. Richard’s Island Pollard and French….
Upper 10 m over 2, 335 km2….vol: km3
*Pore ice most impt.
*Pore ice and segregated ice-constitute over 80% of the total ice volume
20% other types were wedge ice
50% of the top m was excess ice

28. Massive Ice Does not contain much soil Very large exposure
Largest in N. Siberia
C. Yakuta….exposures are 70 m high
N. America
Beaufort Sea, Alaska, MacKenzie, 40 m thick
Very large syngenetic ice wedges
Epigenetic relies on cracking-can’t have thermal crack that high

34. Continued Could be buried Wisconsin Glacier
Ice in the Mackenzie….suggested that it is buried glacier ice
Ice at Peninsula Point
Not glacier ice
MacKay-bore hole data
Logged for soil and ice
85% of cases-ice was underlain by sands or gravels
Overlain was silts and clays
Coast was below sea-emerged later ice

35. MASSIVE ICE BODY Movement of water to the freezing plane
Clay and Silts
Sand
Sand
Movement of water to the freezing plane
Water going to build up lenses in the clay and silts
MASSIVE ICE BODY

36. Ice Wedges Significant True indicators of permafrost
1 to 1.5 m in wide
3 to 4 m in depth
3 to 4 m wide
5 to 10 m deep
DEEP FREEZING

37. Ice Wedge, NWT

38. Ice Wedges (continued)
Favourable environment:
Poorly drained tundra
In the continuous p’frost zone
Further north-arid-less snow
Further south-hard rock, not severe enough
**soils has to be cooled –15 to –20 Deg. C
** rate of cooling is also impt.

39. Gary Island Only 40% of ice wedges crack in any given year
Wire to a recorder
Records when
Wire is broken
Snow cover is a critical factor
To see if cracks will open
**Mackay put up snow fences and stopped cracking
-max. growth after 6 years is 2 mm, < 1 mm/year

40. High Centred Ice Wedge Polygons, NWT
Low Centred Ice Wedge Polygons, NWT

41. Eastwind Lake, Ellesmere Island (2005-2006)
dry ground 10 20 m 1 -1 -2 -3
trough
ice wedge
active layer
low-centred polygon
after Mackay 1980
Hydrologic Connectivity of Tundra Ponds, Ellesmere Island, Nunavut
By May Guan
Seasonal Hydrochemistry of a Polar Oasis Wetland Complex
By Dan Thompson
Photo: K.L. Young

43. Pingo Two basic types Open System Pingo
Occurs in the discontinuous permafrost zone, in areas that were not glaciated during the Wisconsin- Yukon, Alaska
Tend to occur in valley bottom or valley slopes
* can have circulation of groundwater….crucial in open system pingos

45. South
North
Piezometric WT
Pingo
Ice
Permafrost
Groundwater

46. Pingo Continued Pingo is below the top of the water table
Need artesian pressures to start the pingos up
Hydraulic head and ice segregation…these mound the pingo up
Usually the substrate is sands and gravels…allows a permeability…may get a spring and a rupture.

47. Closed System Pingo Form
In continuous permafrost…usually in low relief
pings-Mackenzie Delta
Area has the highest concentration
Pingos require a talik

48. LAKE
P’FROST
P’FROST
TALIK

49. Pond sand Freezing Plane Water will move up To the freezing plane
Pore water
Expulsion as
Freezing takes place

50. Pond is the thinnest layer, Build-up of pressures It will deform there
Ice
Pingo Hts. Pulsate
-Change in hydraulic head
-Hydraulic potential
is changing….
-Impt. Component
Unfrozen

51. IS OPEN/CLOSED DIVISION VALID?

53. Palsas 10- 50 wide 1 to 7 m Is a peat mound Peat overlies mineral soil
Looks like peat plateaus
They form in bogs and occur in the discontinuous zone
wide
1 to
7 m
Peat
P’frost

54. Palsas Continued Snow-low…influences development
Get deeper frost penetration
Peat mounds are higher than surround zones
Water movement is important-have ice formation in the higher areas
More ice lense development raises the mound above the surrounding area….more snow blown off……CIRCULAR ARGUMENT
Process tends to promote a higher mound

55. Continued
Tend to be growing or dying…not in an equilibrium state

56. Ramifications

58. Summary Definition Classification Ice content Genesis Form
Process and Form
Pingos (open and closed)