Pub Date : 2018-10-25DOI: 10.1093/actrade/9780198745853.003.0009
D. Evans
A knowledge of glaciation is important because it provides us with an understanding of glaciers as Earth surface systems face climate change and of the glacial materials beneath the surface. Crucial are glacier-related hazards impacting directly on human society and glacial landforms and sediments lying at the surface of some of the most densely populated parts of our planet. ‘Glaciers, humans, and enduring ice’ considers glacial hazards, such as glacial lake outburst floods, and important engineering considerations, including sediment failure and seepage. It discusses the valuable legacy of past glaciations and asks if Earth is entering a new phase of ice-free conditions, the like of which it has not endured for more than 35 million years.
{"title":"9. Glaciers, humans, and enduring ice","authors":"D. Evans","doi":"10.1093/actrade/9780198745853.003.0009","DOIUrl":"https://doi.org/10.1093/actrade/9780198745853.003.0009","url":null,"abstract":"A knowledge of glaciation is important because it provides us with an understanding of glaciers as Earth surface systems face climate change and of the glacial materials beneath the surface. Crucial are glacier-related hazards impacting directly on human society and glacial landforms and sediments lying at the surface of some of the most densely populated parts of our planet. ‘Glaciers, humans, and enduring ice’ considers glacial hazards, such as glacial lake outburst floods, and important engineering considerations, including sediment failure and seepage. It discusses the valuable legacy of past glaciations and asks if Earth is entering a new phase of ice-free conditions, the like of which it has not endured for more than 35 million years.","PeriodicalId":325510,"journal":{"name":"Glaciation: A Very Short Introduction","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133480129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-25DOI: 10.1093/ACTRADE/9780198745853.003.0005
D. Evans
There is a very wide range of spatial and temporal scales reflected in the types of glacial erosional landforms, from individual millimetre-wide striae that can form over a few days to fjords tens of kilometres long that require hundreds of thousands of years to develop. Erosional landforms can be discussed in categories defined by three spatial scales: microscale, macroscale, and megascale, the latter also including whole landscapes that have unmistakable glacial erosional origins. ‘Eroded by ice’ describes these different erosional forms and explains that they are rarely viewed in isolation because microscale erosional marks are superimposed on macroscale forms, which in turn are superimposed on megascale surfaces to constitute erosional landscapes.
{"title":"5. Eroded by ice","authors":"D. Evans","doi":"10.1093/ACTRADE/9780198745853.003.0005","DOIUrl":"https://doi.org/10.1093/ACTRADE/9780198745853.003.0005","url":null,"abstract":"There is a very wide range of spatial and temporal scales reflected in the types of glacial erosional landforms, from individual millimetre-wide striae that can form over a few days to fjords tens of kilometres long that require hundreds of thousands of years to develop. Erosional landforms can be discussed in categories defined by three spatial scales: microscale, macroscale, and megascale, the latter also including whole landscapes that have unmistakable glacial erosional origins. ‘Eroded by ice’ describes these different erosional forms and explains that they are rarely viewed in isolation because microscale erosional marks are superimposed on macroscale forms, which in turn are superimposed on megascale surfaces to constitute erosional landscapes.","PeriodicalId":325510,"journal":{"name":"Glaciation: A Very Short Introduction","volume":"02 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130108725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-25DOI: 10.1093/actrade/9780198745853.003.0001
D. Evans
‘Glacier ice: discovery and understanding’ considers how and why glaciers are formed and the history of the study of glaciers, which has enhanced our knowledge. Glacier ice will form wherever the combined effects of precipitation (specifically snow), low temperatures, and topography create the optimum conditions. These optimum conditions are met in regions of high altitude and high latitude, but can be met at high altitudes in equatorial regions and lower altitudes towards the poles. Other conditions must also be satisfied: aspect, relief, and the distance from the nearest moisture source. The balance and equilibrium of glaciers is also explained along with their key features and how they act as archives of climate change.
{"title":"1. Glacier ice: discovery and understanding","authors":"D. Evans","doi":"10.1093/actrade/9780198745853.003.0001","DOIUrl":"https://doi.org/10.1093/actrade/9780198745853.003.0001","url":null,"abstract":"‘Glacier ice: discovery and understanding’ considers how and why glaciers are formed and the history of the study of glaciers, which has enhanced our knowledge. Glacier ice will form wherever the combined effects of precipitation (specifically snow), low temperatures, and topography create the optimum conditions. These optimum conditions are met in regions of high altitude and high latitude, but can be met at high altitudes in equatorial regions and lower altitudes towards the poles. Other conditions must also be satisfied: aspect, relief, and the distance from the nearest moisture source. The balance and equilibrium of glaciers is also explained along with their key features and how they act as archives of climate change.","PeriodicalId":325510,"journal":{"name":"Glaciation: A Very Short Introduction","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115995446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-25DOI: 10.1093/ACTRADE/9780198745853.003.0004
D. Evans
Glaciers and ice sheets create landscape change in three main ways: erosion, deposition, and deformation. The combination of these processes has given glaciers the reputation of being phenomenally efficient changers of landscapes. But in reality they modify the Earth’s surface only gradually, eroding and moving material in stages of various duration via a complex spatial and temporal mosaic of processes. ‘The glacial dirt machine’ considers these processes in turn. Erosion includes direct glacial erosion as well as glacifluvial or meltwater-related processes. A wide range of other geomorphological processes—paraglacial processes—are activated and indeed are at their most dynamic immediately after deglaciation.
{"title":"4. The glacial dirt machine","authors":"D. Evans","doi":"10.1093/ACTRADE/9780198745853.003.0004","DOIUrl":"https://doi.org/10.1093/ACTRADE/9780198745853.003.0004","url":null,"abstract":"Glaciers and ice sheets create landscape change in three main ways: erosion, deposition, and deformation. The combination of these processes has given glaciers the reputation of being phenomenally efficient changers of landscapes. But in reality they modify the Earth’s surface only gradually, eroding and moving material in stages of various duration via a complex spatial and temporal mosaic of processes. ‘The glacial dirt machine’ considers these processes in turn. Erosion includes direct glacial erosion as well as glacifluvial or meltwater-related processes. A wide range of other geomorphological processes—paraglacial processes—are activated and indeed are at their most dynamic immediately after deglaciation.","PeriodicalId":325510,"journal":{"name":"Glaciation: A Very Short Introduction","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124114743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-25DOI: 10.1093/ACTRADE/9780198745853.003.0007
D. Evans
Glacial geomorphologists combine two geomorphological approaches—process studies, including empirical field measurement and laboratory experiments, and form analogy, or reconstructive geomorphology—in an attempt to make sense of the vast array of glacial depositional landforms created by the leaky, restless, and constantly shuffling conveyor belt or ‘dirt machine’ that is the glacier. ‘Landforms from the restless conveyor belt’ describes the range of glacigenic features that are spatially defined ‘sediment–landform associations’, and which are categorized by a process-form-based framework. These include subglacial footprints, ice-marginal moraines, supraglacial associations, glacifluvial assemblages, and subaqueous assemblages.
{"title":"7. Landforms from the restless conveyor belt","authors":"D. Evans","doi":"10.1093/ACTRADE/9780198745853.003.0007","DOIUrl":"https://doi.org/10.1093/ACTRADE/9780198745853.003.0007","url":null,"abstract":"Glacial geomorphologists combine two geomorphological approaches—process studies, including empirical field measurement and laboratory experiments, and form analogy, or reconstructive geomorphology—in an attempt to make sense of the vast array of glacial depositional landforms created by the leaky, restless, and constantly shuffling conveyor belt or ‘dirt machine’ that is the glacier. ‘Landforms from the restless conveyor belt’ describes the range of glacigenic features that are spatially defined ‘sediment–landform associations’, and which are categorized by a process-form-based framework. These include subglacial footprints, ice-marginal moraines, supraglacial associations, glacifluvial assemblages, and subaqueous assemblages.","PeriodicalId":325510,"journal":{"name":"Glaciation: A Very Short Introduction","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122336896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-25DOI: 10.1093/actrade/9780198745853.003.0002
D. Evans
The shape and size of glacier ice bodies (their morphology) is dictated by the interplay between climate and topography, and a classification scheme has been adopted to cover all the variants that lie on a spatial and temporal continuum of morphologies. ‘Glacier ice: definitions and dynamics’ explains that in any one location over time different glacier morphologies may evolve. It describes how water as a liquid is fundamental to glacial processes, and considers a range of glacier dynamics and flow mechanics, including the processes and causes of ice deformation, creeping ice, sliding beds, and glacial surge. It also explains subglacial bed deformation, a relatively newly discovered process that emerged only in the 1970s.
{"title":"2. Glacier ice: definitions and dynamics","authors":"D. Evans","doi":"10.1093/actrade/9780198745853.003.0002","DOIUrl":"https://doi.org/10.1093/actrade/9780198745853.003.0002","url":null,"abstract":"The shape and size of glacier ice bodies (their morphology) is dictated by the interplay between climate and topography, and a classification scheme has been adopted to cover all the variants that lie on a spatial and temporal continuum of morphologies. ‘Glacier ice: definitions and dynamics’ explains that in any one location over time different glacier morphologies may evolve. It describes how water as a liquid is fundamental to glacial processes, and considers a range of glacier dynamics and flow mechanics, including the processes and causes of ice deformation, creeping ice, sliding beds, and glacial surge. It also explains subglacial bed deformation, a relatively newly discovered process that emerged only in the 1970s.","PeriodicalId":325510,"journal":{"name":"Glaciation: A Very Short Introduction","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116054404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-25DOI: 10.1093/ACTRADE/9780198745853.003.0003
David J. A. Evans
The ‘glacial theory’ championed by Louis Agassiz in the 19th century saw the beginning of the geological community’s partial acceptance of the concept of multiple and more extensive glaciations. Formal recognition of multiple glaciations came in 1909 with Penck and Brückner’s Alpine model. Since then, research on the Earth’s climate record has established a firm understanding of the nature and pace of climate change over the last 2.6 million years and the impact these changes have had on glacier development and extent. ‘Glaciers through time’ considers the periods of ice ages, glacials, and interglacials, describing changes in ice sheets, mountain icefields, and the impact of melting glacier ice on sea level rise.
{"title":"3. Glaciers through time","authors":"David J. A. Evans","doi":"10.1093/ACTRADE/9780198745853.003.0003","DOIUrl":"https://doi.org/10.1093/ACTRADE/9780198745853.003.0003","url":null,"abstract":"The ‘glacial theory’ championed by Louis Agassiz in the 19th century saw the beginning of the geological community’s partial acceptance of the concept of multiple and more extensive glaciations. Formal recognition of multiple glaciations came in 1909 with Penck and Brückner’s Alpine model. Since then, research on the Earth’s climate record has established a firm understanding of the nature and pace of climate change over the last 2.6 million years and the impact these changes have had on glacier development and extent. ‘Glaciers through time’ considers the periods of ice ages, glacials, and interglacials, describing changes in ice sheets, mountain icefields, and the impact of melting glacier ice on sea level rise.","PeriodicalId":325510,"journal":{"name":"Glaciation: A Very Short Introduction","volume":"136 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128562654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-25DOI: 10.1093/actrade/9780198745853.003.0006
D. Evans
There are two types of primary glacial sediment created by glacier beds acting as shearing zones within which a subglacial deforming layer is developed: till and glacitectonite. ‘Deposited by ice’ explains how these deposits represent a continuum of materials, the products of the various stages of sediment mixing creating diamicton. Where a glacier acts to deform and gradually mix its substrate it will create a melange or glacitectonite. At the highly deformed end of the spectrum, the material is close to being fully homogenized into a diamicton and at this point it becomes a subglacial till. Erratics—boulders carried by glacier ice, often over long distances—are also described.
{"title":"6. Deposited by ice","authors":"D. Evans","doi":"10.1093/actrade/9780198745853.003.0006","DOIUrl":"https://doi.org/10.1093/actrade/9780198745853.003.0006","url":null,"abstract":"There are two types of primary glacial sediment created by glacier beds acting as shearing zones within which a subglacial deforming layer is developed: till and glacitectonite. ‘Deposited by ice’ explains how these deposits represent a continuum of materials, the products of the various stages of sediment mixing creating diamicton. Where a glacier acts to deform and gradually mix its substrate it will create a melange or glacitectonite. At the highly deformed end of the spectrum, the material is close to being fully homogenized into a diamicton and at this point it becomes a subglacial till. Erratics—boulders carried by glacier ice, often over long distances—are also described.","PeriodicalId":325510,"journal":{"name":"Glaciation: A Very Short Introduction","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130921319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-25DOI: 10.1093/actrade/9780198745853.003.0008
David J. A. Evans
To reconstruct the former extent and dynamics of ice sheets and glaciers requires a knowledge of process-form relationships that goes beyond individual landform types. Instead, glacial geomorphologists need to analyse large areas of glaciated terrain in a more holistic way, combining the whole range of glacial landforms and sediments to reconstruct glacier systems of the past, a subject now known as palaeoglaciology. ‘Glaciers of the past’ explains how the combination of aerial imagery and landform analysis is used in palaeoglaciological reconstruction. Increasingly powerful computers are making it possible to compile sophisticated numerical models that use our knowledge of glaciological processes and ice-core-derived palaeoclimate data to create three-dimensional glacier and ice sheet reconstructions.
{"title":"8. Glaciers of the past","authors":"David J. A. Evans","doi":"10.1093/actrade/9780198745853.003.0008","DOIUrl":"https://doi.org/10.1093/actrade/9780198745853.003.0008","url":null,"abstract":"To reconstruct the former extent and dynamics of ice sheets and glaciers requires a knowledge of process-form relationships that goes beyond individual landform types. Instead, glacial geomorphologists need to analyse large areas of glaciated terrain in a more holistic way, combining the whole range of glacial landforms and sediments to reconstruct glacier systems of the past, a subject now known as palaeoglaciology. ‘Glaciers of the past’ explains how the combination of aerial imagery and landform analysis is used in palaeoglaciological reconstruction. Increasingly powerful computers are making it possible to compile sophisticated numerical models that use our knowledge of glaciological processes and ice-core-derived palaeoclimate data to create three-dimensional glacier and ice sheet reconstructions.","PeriodicalId":325510,"journal":{"name":"Glaciation: A Very Short Introduction","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122768114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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