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Table of Contents - Memoir 190

Plugs and Plug Circles: A Basic Form of Petterned Ground, Cornwallis Island, Arctic Canada — Origin and Implications

Abstract

Abbreviations

Introduction and acknowledgments

General

Climate
Soil temperatures
Geography and geology
Terminology—patterned ground
Terminology—soils

Earlier observations

Occurrences in emerged beach gravel

Experimental site C (ES C)
Excavations
PE 82-5
PE 82-6
PE 85-8
PE 86-4
PE 86-6
PE 89-1
PE 89-2
PE 90-1
PE 90-2
PE 95-1
PE 95-2
PE 95-3
Discussion Dye experiments
DE 86-1
DE 86-2 Observations at Sheringham Point

Occurrences in miscellaneous deposits

Excavations
PE 81-1
PE 82-1
PE 83-3
Dye experiments
DE 86-3,-4 Other observations
Vicinity VOR installation
Signal Hill plateau

Occurrences in disintegrating bedrock

Excavations
PE 82-4
PE 86-3
PE 88-1 Other observations
Resolute area
Sheringham Point
Gypsum diapir, west coast, Cornwallis Island
Mould Bay, Prince Patrick Island

Miscellaneous observations

Recent activity
Terrain influences
Weathering

Transitional patterned-ground forms

Resolute area
Bench near northwest end of "Airport Ridge"
Vicinity ES B
S-Circle Excavation 88-A and vicinity
Vicinity North Transmitter Station
Vicinity TACAN building
Vicinity VOR installation
Plateau above Small Lake Taylor River bend
Lake 2 km north of Helen Haven

Characteristics of plugs and plug circles

General
Constitution: Review
Constitution: Discussion
Morphology, structure, and fabric: Review
Morphology, structure, and fabric: Discussion
Pattern: Review
Pattern: Discussion
Other characteristics: Review
Other characteristics: Discussion
Observations in other regions

Hypotheses of origin

General
Radial frost sorting
General
Problems Water and soil convection due to density changes in water between 0 and 4 °C
General
Problems
Modified hypothesis—A free-convection model
Problems Soil circulation due to freeze-thaw pumping
General
Problems Soil circulation due to moisture-controlled changes in density
General
Problems Soil circulation associated with differential frost heaving
General
Problems Soil loading (loadcasting)
General
Problems Differential frost heaving and surfaceward seepage
Differential frost heaving
Surfaceward seepage
Initiation
Dynamics
Problems

Pattern evolution

Summary and conclusions

Plugs and plug circles as patterned-ground forms
Cornwallis Island occurrences
Regional distribution
Origin
Transitional forms
Significance

Tables 1–16

Appendix A: Climate summary, Resolute A, Cornwallis Island, N.W.T., 1947–1990

Appendix B: Soil temperatures, Resolute, Cornwallis Island, N.W.T.

Appendix C:
Radiocarbon dates of selected specimens from Resolute area, Cornwallis Island, N.W.T.

Endnotes

References cited

Index