Rockglaciers: Indicators for the Present and Former Geoecology in High Mountain Environments

ISBN-13: 9783642800955 / Angielski / Miękka / 2012 / 331 str.

Dietrich Barsch

Opis

Rockglaciers are the visible expression of the creep of mountain permafrost. They are indicative of special geo-ecologic and geomorphic conditions regarding thermal situation, talus production, hydrology, and hazards in high mountain environments of all major mountain systems on earth. As relict features, they are of great paleoclimatic value. This book presents a systematic treatment of this landform in its environmental context.

Spis treści

1 Definitions.- 2 Historical Development of the Term Rockglacier.- 3 Rockglaciers: Description and Morphometry.- 3.1 General Description.- 3.2 Form Types.- 3.3 Morphometric Parameters.- 3.3.1 Rockglacier Sizes.- 3.3.2 Tongue-Shaped Rockglaciers.- 3.3.3 Lobate Rockglaciers.- 3.3.4 Rockglacier Thickness.- 3.3.5 Surface Relief.- 3.3.6 Rockglacier Surface and Source Area.- 4 Rockglacier Taxonomy.- 5 Rockglacier Distribution.- 5.1 General Information.- 5.2 Local Rockglacier Distribution.- 5.2.1 The Alps.- 5.2.2 The Mountains of Northern Europe.- 5.2.3 The Pyrenees.- 5.2.4 North American Mountains.- 5.2.5 The Andes of Central and South America.- 5.2.6 The Mountains of Asia.- 5.2.7 The Southern Alps.- 5.2.8 Antarctic Mountains.- 5.2.9 Conclusions.- 6 Rockglacier Material, Surficial Fabric and Internal Structure.- 6.1 Rock Type and Grain Size at and below the Surface.- 6.1.1 Rock Type.- 6.1.2 Grain Sizes at the Surface.- 6.1.3 Development of the Bouldery Mantle.- 6.1.4 Surface Fabric.- 6.1.5 Grain Sizes below the Bouldery Mantle.- 6.2 Internal Structure.- 6.2.1 Direct Information.- 6.2.1.1 Excavations, Outcrops, Tunnels.- 6.2.1.2 Smaller Boreholes.- 6.2.1.3 The Deep Borehole through the Rockglacier Murtèl I.- 6.2.2 Indirect Information.- 6.2.2.1 Seismic Information.- 6.2.2.2 Geoelectric Soundings.- 6.2.2.3 Radio-Echo Soundings.- 6.2.2.4 Gravimetry.- 6.2.2.5 Borehole Geophysics and Related Measurements.- 6.2.2.6 BTS Measurements.- 6.2.2.7 Summary: The Inner Core of an Active Rockglacier.- 6.3 The Active Layer on Rockglaciers.- 7 Rockglacier Movement, Velocity, and Rheology.- 7.1 The Horizontal and Vertical Movement of Active Rockglaciers.- 7.1.1 Measurement Methods.- 7.1.2 Annual Horizontal Displacement.- 7.1.3 Long-Term Annual Averages.- 7.1.4 Long-Term Estimates.- 7.1.5 Longer Time Series.- 7.1.6 Monthly and Seasonal Measurements.- 7.1.7 Vertical Displacement.- 7.1.8 Conclusion.- 7.2 Geometry of Movement.- 7.2.1 The General Flow Patterns of Active Rockglaciers.- 7.2.1.1 Gruben Rockglacier.- 7.2.1.2 Macun Rockglacier.- 7.2.1.3 Arapaho Rockglacier.- 7.2.2 Horizontal Velocity on Longitudinal and Cross-Sectional Profiles.- 7.2.3 Surface and Subsurface Velocity.- 7.3 Rheologie Considerations.- 7.3.1 Shear Stress and Strain Rates in Active Rockglaciers.- 7.3.2 The Rheological Description of Active Rockglaciers.- 7.4 Rockglacier Movement and Climate.- 7.5 Discussion of Rockglacier Movement.- 8 Rockglacier Genesis and the Relation to Similar-Looking Landforms.- 8.1 Rockglacier Genesis.- 8.1.1 The Formation of Active Rockglaciers.- 8.1.1.1 Talus Rockglaciers.- 8.1.1.2 Debris Rockglaciers.- 8.1.1.3 Special Rockglaciers.- 8.1.1.4 Problematic Cases.- 8.1.2 Inactive Rockglaciers.- 8.1.3 Relict (Fossil) Rockglaciers.- 8.2 Published Hypotheses of Rockglacier Formation.- 8.2.1 Mass-Movement Hypotheses.- 8.2.1.1 The Bergsturz Hypothesis in General.- 8.2.1.2 Landslide Influences.- 8.2.2 The Glacial Hypothesis.- 8.2.2.1 Debris-Covered Glaciers and Thermokarst.- 8.2.2.2 Transition from True Glaciers to Rockglaciers?.- 8.2.2.3 The Moraine Hypothesis.- 8.2.3 The Periglacial (Blockstream) Hypothesis.- 8.3 True Rockglaciers under Wrong Labels.- 8.3.1 The Östrem Ice-Cored Moraine Concept.- 8.3.2 The Protalus Rampart Concept.- 9 The Age of Rockglaciers.- 9.1 The Age of Active Rockglaciers.- 9.2 The Age of Climatic Inactive Rockglaciers.- 9.3 The Age of Relict (Fossil) Rockglaciers.- 10 Rockglaciers and the High Mountain Environment.- 10.1 Active Rockglaciers and Mountain Permafrost.- 10.2 Rockglaciers in the Coarse Debris Cycle.- 10.2.1 Rockglaciers and Talus Production.- 10.2.2 Rockglacier Size and Source Area.- 10.2.3 Rockglaciers as a Debris Transport System.- 10.3 Rockglaciers and Climate.- 10.3.1 Rockglaciers and Present Climate.- 10.3.2 Relict Rockglaciers and Paleoclimate Reconstruction.- 10.3.3 Reactivation of Inactive or Relict Rockglaciers.- 10.3.4 Rockglaciers and Climatic Change.- 10.4 Rockglaciers in the Alpine Hydrological Cycle.- 10.4.1 Rockglaciers as a Water Store.- 10.4.2 Discharge from Rockglacier Permafrost.- 10.4.3 Fluctuations in Rockglacier Permafrost Storage.- 10.5 Rockglaciers as Hazards in Alpine Environments.- 10.6 The Environment of Active Rockglaciers.- 11 Summary and Outstanding Problems.- 12 References.- Index of Place Names.