Periglacial Geomorphology

Title Page

Copyright Page

Contents

Preface

Acknowledgements

Chapter 1 Introduction

1.1 The Periglacial Concept: Definitions and Scope

1.2 The Periglacial Realm

1.3 The Development of Periglacial Geomorphology

1.4 Periglacial Geomorphology: The Quaternary Context

1.5 The Aims and Organization of this Book

Chapter 2 Periglacial Environments

2.1 Introduction

2.2 Periglacial Climates

2.2.1 Arctic Climates

2.2.2 Low-arctic and Subarctic Continental Interiors

2.2.3 Maritime Periglacial Environments

2.2.4 Antarctica

2.2.5 Alpine Periglacial Environments

2.2.6 The Qinghai-Tibet Plateau

2.3 Soils in Periglacial Environments

2.4 Vegetation Cover in Periglacial Environments

2.5 Synthesis

Chapter 3 Ground Freezing and Thawing

3.1 Introduction

3.2 Ground Heating and Cooling

3.2.1 Basic Concepts

3.2.2 Conduction of Heat into the Ground

3.2.3 Estimating Depth of Freezing and Thawing

3.2.4 Temperature Change with Depth

3.2.5 Temperature Variations with Depth

3.3 Soil Freezing

3.4 Ice Segregation in Freezing Soils

3.4.1 Cryosuction

3.4.2 Ice Segregation

3.5 Thaw Consolidation

3.6 Synthesis

Chapter 4 Permafrost

4.1 Introduction

4.2 Permafrost Thermal Regime

4.3 Classification of Permafrost

4.4 Detection, Mapping and Modelling of Permafrost

4.4.1 Geophysical Surveys

4.4.2 BTS Measurements

4.4.3 Modelling of Permafrost Distribution and Temperature

4.5 Permafrost Distribution

4.5.1 Global Distribution

4.5.2 Relict Permafrost

4.5.3 Local Variations in Permafrost Distribution

4.6 Permafrost–glacier Interactions

4.7 The Geomorphic Importance of Permafrost

Chapter 5 Ground Ice and Cryostratigraphy

5.1 Introduction

5.2 Genetic Classification of Ground Ice

5.2.1 Pore Ice

5.2.2 Closed Cavity Ice

5.2.3 Segregated Ice

5.2.4 Intrusive Ice

5.2.5 Wedge Ice and Vein Ice

5.2.6 Dilation Crack Ice

5.2.7 Pool Ice

5.2.8 Buried ice

5.2.9 Transitional, Compound and Modified Ice Types

5.3 Description of Ground Ice

5.3.1 Ice Content

5.3.2 Cryostructures in Unlithified Sediments

5.3.3 Cryostructures in Rock

5.3.4 Cryofacies

5.4 Ice Contacts

5.5 Cryostratigraphy

5.6 The Transition Zone

5.7 Massive Ground Ice

5.7.1 Massive Intrasedimental Ice

5.7.2 Buried Glacier Ice

5.7.3 Massive Ice Hybrids

5.8 Yedoma

5.8.1 Terminology, Distribution and Characteristics

5.8.2 Age and Environment of Deposition

5.8.3 Formation of Yedoma

Chapter 6 Thermal Contraction Cracking: Ice Wedges and Related Landforms

6.1 Introduction

6.2 Thermal Contraction Cracking and Polygon Evolution

6.3 Ice Veins and Ice Wedges

6.4 Ice-wedge Polygons

6.5 Sand Veins and Sand Wedges

6.6 Composite Veins and Composite Wedges

6.7 Sand-wedge Polygons

6.8 Frost Cracking of Seasonally Frozen Ground

6.9 Thaw Modification of Frost Wedges

6.9.1 Thaw Modification of Ice Wedges

6.9.2 Thaw Modification of Sand Wedges and Composite Wedges

6.10 Frost-Wedge Pseudomorphs and Frost Polygons in Areas of Past Permafrost

6.10.1 Frost-wedge Pseudomorphs

6.10.2 Identification of Frost-wedge Pseudomorphs

6.10.3 Relict Frost Polygons

6.10.4 Dating of Frost-wedge Pseudomorphs and Primary Sand Wedges

6.10.5 Palaeoenvironmental Implications

Chapter 7 Pingos, Palsas and other Frost Mounds

7.1 Introduction

7.2 Characteristics of Pingos

7.3 Hydrostatic Pingos

7.3.1 Pingo Formation and Growth

7.3.2 Pingo Ice

7.3.3 Pingo Degradation and Collapse

7.4 Hydraulic Pingos

7.5 Pingo Problems and Problem Pingos

7.6 Segregation Ice Mounds: Palsas, Lithalsas and Related Landforms

7.7 Palsas

7.7.1 Palsa Structure

7.7.2 Palsa Growth and Collapse

7.8 Peat Plateaus

7.9 Lithalsas

7.10 Permafrost Plateaus

7.11 Other Permafrost Mounds

7.12 Ephemeral Frost Mounds

7.13 Relict Permafrost Mounds

7.13.1 Relict Pingos

7.13.2 Relict Lithalsas

Chapter 8 Thermokarst

8.1 Introduction

8.2 Thermokarst Lakes and Drained Lake Basins

8.2.1 Characteristics of Thermokarst Lakes

8.2.2 Formation of Thermokarst Lakes: Initiation

8.2.3 Thermokarst Lake Growth

8.2.4 Oriented Lakes

8.2.5 Thermokarst Lake Sedimentation

8.2.6 Thermokarst Lake Hydrology and Drainage

8.2.7 Drained Lake Basins

8.2.8 Cyclic and Alternative Models of Thermokarst Lake Evolution

8.2.9 Thermokarst Lake Dynamics

8.3 Thermokarst Pits, Bogs and Fens

8.4 Retrogressive Thaw Slumps

8.4.1 Characteristics of Retrogressive Thaw Slumps

8.4.2 Thaw Slump Processes

8.4.3 Temporal Changes in Slump Activity

8.5 Small-scale Thermokarst Features: Beaded Streams, Sinkholes and Thermokarst Gullies

8.6 Sediment Structures associated with Thermokarst

8.7 Relict Thermokarst Phenomena

Chapter 9 Seasonally Frozen Ground Phenomena

9.1 Introduction

9.2 Upfreezing of Clasts

9.3 Frost Heave of Bedrock

9.4 Patterned Ground: The Embroidery on the Landscape

9.5 Patterned Ground Processes

9.5.1 Differential Frost Heave

9.5.2 Buoyancy-induced Soil Circulation

9.6 Sorted Patterned Ground

9.6.1 Characteristics

9.6.2 Formation

9.6.3 Environmental and Palaeoenvironmental Significance

9.7 Nonsorted Patterned Ground

9.7.1 Vegetation-defined Nonsorted Circles (Frost Boils) and Stripes

9.7.2 Earth Hummocks and Relief Stripes

9.7.3 Environmental and Palaeoenvironmental Significance

9.8 Cryoturbations

9.8.1 Terminology and Characteristics

9.8.2 Formation

9.8.3 Interpretation of Relict Cryoturbations

9.9 Pedogenic Effects of Freezing and Thawing

9.10 Fragipans

9.11 Synthesis

Chapter 10 Rock Weathering and Associated Landforms

10.1 Introduction

10.2 Physical Weathering Processes

10.2.1 Frost Weathering

10.2.2 Hydration Shattering

10.2.3 Thermal Stress

10.2.4 Salt Weathering

10.2.5 Stress Release and Tectonic Stress

10.3 Chemical Weathering Processes

10.3.1 Chemical Weathering in Cold Environments

10.4 Biotic Weathering Processes

10.5 Weathering Processes in Periglacial Environments

10.6 Cold-climate Karst

10.7 Tors

10.8 Blockfields and Related Periglacial Regolith Covers

10.8.1 Classification and Characteristics

10.8.2 Autochthonous Blockfields

10.8.3 Age and Origin: The Blockfield Enigma

10.8.4 Blockfields and Glaciation: Periglacial Trimlines

10.8.5 Allochthonous Block Deposits: Blockslopes and Blockstreams

10.9 Brecciated Bedrocks

Chapter 11 Periglacial Mass Movement and Hillslope Evolution

11.1 Introduction

11.2 Solifluction Processes

11.2.1 Needle-ice Creep

11.2.2 Frost Creep

11.2.3 Gelifluction

11.2.4 Plug-like Deformation

11.2.5 Rates of Movement

11.3 Solifluction Landforms

11.3.1 Solifluction Terraces and Lobes

11.3.2 Ploughing Boulders and Braking Blocks

11.4 Pleistocene Solifluction Landforms and Slope Deposits

11.5 Active-layer Failures

11.6 Permafrost Creep

11.7 Nivation

11.8 Cryoplanation

11.8.1 Cryoplanation Terraces

11.8.2 Cryopediments

11.9 Slope Form and Slope Evolution

Chapter 12 Talus Slopes and Related Landforms

12.1 Introduction

12.2 Rockfall Talus

12.2.1 Characteristics

12.2.2 Models of Talus Accumulation

12.2.3 Rockfall in Periglacial Environments

12.2.4 Talus Shift

12.2.5 Stratified Talus Deposits

12.2.6 Relict Talus Accumulations in Former Periglacial Environments

12.3 The Geomorphic Role of Snow Avalanches

12.3.1 Characteristics of Snow Avalanches

12.3.2 Avalanche Modification of Talus Slopes

12.3.3 Other Aspects of Snow?Avalanche Erosion and Deposition

12.3.4 The Significance of Snow?Avalanche Activity

12.3.5 Relict Avalanche Landforms and Deposits

12.4 Debris-flow Activity

12.4.1 Characteristics of Debris Flows

12.4.2 Debris-flow Processes

12.4.3 Debris Flows as Agents of Sediment Transport

12.4.4 Relict Debris-Flow Landforms and Deposits

12.5 Rock Glaciers

12.5.1 Definition and Classification

12.5.2 Rock-glacier Distribution

12.5.3 Rock-glacier Morphology

12.5.4 Rock-glacier Structure

12.5.5 Rates and Processes of Rock-Glacier Movement

12.5.6 Rock Glaciers and Climate

12.5.7 Relict Rock Glaciers

12.6 Pronival (Protalus) Ramparts

12.6.1 Characteristics of Pronival Ramparts

12.6.2 Rampart Formation

12.6.3 Relict Pronival Ramparts

12.7 Synthesis

Chapter 13 Fluvial Processes and Landforms

13.1 Introduction

13.2 Periglacial Hydrology

13.2.1 Active-layer Dynamics in High-Arctic Environments

13.2.2 Hillslope Hydrology in High-Arctic Environments

13.2.3 River Runoff in High-Arctic Environments

13.2.4 Water Balance in High-Arctic Environments

13.2.5 River Runoff Regimes in Other Periglacial Environments

13.3 Slopewash

13.3.1 Surface Wash

13.3.2 Subsurface Wash

13.4 Slushflows

13.5 Sediment Transport in Periglacial Rivers

13.6 Bank and Channel Erosion

13.6.1 The Role of Snow and Ice

13.6.2 Thermal Erosion

13.7 River Channels

13.7.1 Bedrock Channels

13.7.2 Meandering and Anastomosing Channels

13.7.3 Braided Channels

13.8 Alluvial Landforms in Periglacial Environments

13.8.1 Sandar

13.8.2 Alluvial Fans

13.8.3 Deltas

13.9 Valley Form

13.9.1 V-shaped Valleys and Rock Gorges

13.9.2 Valley Asymmetry

13.10 Pleistocene Periglacial Rivers

13.11 Synthesis

Chapter 14 Wind Action

14.1 Introduction

14.2 Aeolian Processes

14.3 Wind Erosion in Present Periglacial Environments

14.3.1 Environmental Controls on Wind Erosion

14.3.2 Erosional Landforms

14.4 Aeolian Deposits in Present Periglacial Environments

14.4.1 Sandy Aeolian Deposits

14.4.2 Dunefields

14.4.3 Sand Sheets

14.4.4 Fluvio-aeolian Deposits

14.4.5 Niveo-aeolian Deposits

14.4.6 Loessic (Silt) Deposits and Silt–Sand Intergrades

14.4.7 Montane Aeolian Systems

14.4.8 The Qinghai-Tibet Plateau

14.5 Quaternary Aeolian Deposits

14.5.1 Pleistocene Coversands and Dunefields

14.5.2 Pleistocene Coversands and Dunefields of the North European Plain

14.5.3 Pleistocene Loess Deposits

14.5.4 The Depositional History of Pleistocene Loess Deposits

14.6 Synthesis

Chapter 15 Periglacial Coasts

15.1 Introduction

15.2 The Nature of Periglacial Coasts

15.3 The Role of Ice in Shoreline Evolution

15.4 Ice-rich Permafrost Coasts

15.5 Thermokarst Coasts

15.6 Barrier Coasts

15.7 Salt Marshes and Tidal Flats

15.8 Rock Coasts

15.9 Raised and Inherited Shorelines

15.10 Lake Shorelines

15.11 Synthesis

Chapter 16 Past Periglacial Environments

16.1 Introduction

16.2 Palaeoenvironmental Reconstruction Based on Periglacial Features

16.2.1 Preservation Potential

16.2.2 Identification of Relict Periglacial Features

16.2.3 Relative Age Dating: Stratigraphy and Morphostratigraphy

16.2.4 Absolute Age Dating

16.2.5 Palaeoenvironmental Interpretation

16.3 Past Periglacial Environments of the British Isles

16.3.1 Chronological Framework

16.3.2 Periglacial Regions in the British Isles

16.4 Pre-Late Devensian Periglacial Features in the British Isles

16.4.1 Evidence for Past Permafrost

16.4.2 Loess and Coversands

16.5 The Dimlington Stade in the British Isles

16.5.1 Evidence for Past Permafrost

16.5.2 Relict Frost Wedges and Frost Polygons

16.5.3 Relict Ground-Ice Features: Pingos, Lithalsas and Thermokarst Landforms

16.5.4 Permafrost Extent and Thickness

16.5.5 Loess and Coversands

16.6 The Younger Dryas (Loch Lomond) Stade in the British Isles

16.6.1 Evidence for Past Permafrost in Upland Areas During the Younger Dryas Stade

16.6.2 Evidence for Past Permafrost in Lowland Areas During the Younger Dryas Stade

16.6.3 Younger Dryas Aeolian Deposits

16.7 Past Periglacial Environments of the British Isles: Commentary

16.8 Late Weichselian Periglacial Environments in Continental Europe

16.8.1 Late Weichselian Permafrost in Europe

16.8.2 Late Weichselian Coversands in Europe

16.8.3 Late Weichselian Loess Deposits in Europe

16.9 Late Wisconsinan Periglacial Environments in North America

16.9.1 Evidence for Late Wisconsinan Permafrost in North America

16.9.2 Late Wisconsinan Aeolian Deposits in North America

16.10 Permafrost Extent in the Northern Hemisphere During the Last Glacial Stage

16.11 Concluding Comments

Chapter 17 Climate Change and Periglacial Environments

17.1 Introduction

17.2 Permafrost Degradation

17.2.1 Recent Trends in the Thermal State of Permafrost

17.2.2 Active-layer Thickness

17.2.3 Recent Changes in Permafrost Extent

17.2.4 Projections

17.3 Geomorphological Implications of Climate Change in the Circumpolar North

17.3.1 Ice-wedge Degradation and Thermokarst Gullying

17.3.2 Degradation of Ground-ice Mounds

17.3.3 Thermokarst Lakes, Ponds, Bogs and Fens

17.3.4 Slope Processes

17.3.5 Arctic Rivers

17.3.6 Arctic Coasts

17.4 Geomorphological Implications of Climate Change in High Mountain Environments

17.4.1 Climate Change and High-Alpine Permafrost

17.4.2 Rock-slope Instability: Rockfalls and Rock Avalanches

17.4.3 Talus, Protalus Ramparts and Rock Glaciers

17.4.4 Debris-flow Activity

17.5 Climate Change, Permafrost Degradation and Greenhouse Gas Emissions

17.5.1 Permafrost Carbon: Reserves, Emissions and Projections

17.5.2 Thermokarst Development and Carbon Emissions

17.5.3 Greenhouse Gas Emissions from Subsea Permafrost

17.5.4 Permafrost Degradation and the Global Carbon Cycle

17.6 Conclusion

Text Abbreviations, Units and Symbols Employed in Equations

References

Index

Supplemental Images

EULA