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Mountain glaciation and landscape evolution
Geomorphology 103 (2009) 155–157
Contents lists available at ScienceDirect
Geomorphology j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / g e o m o r p h
Editorial
Mountain glaciation and landscape evolution
Keywords: Mountain glaciation Glaciers Geochronology Uplift Erosion
Mountain glaciers are important geomorphic agents and they play a significant role in denuding landscapes and transferring sediment within and beyond mountain systems. In recent years an important paradigm shift occurred from considering mountain glacial systems as simply responding to climate change within a region that was tectonically uplifted to considering mountain glaciers as agents that help drive mountain uplift, essentially by denudational unloading, and as controls that help limit topography. Significant debate exists over the importance of glaciers versus other processes, such as fluvial erosion and mass movement, in shaping mountain landscapes. Furthermore, long-term rates of denudation are found to be an order of magnitude less than the short-term values in many regions where sediment yields from glaciated catchments have been used to determine rates of glacial erosion. Currently, the questions of what limits topography and of what role glaciers play in orographic belts, spatially and temporally, and of how rates of denudation vary over time, remain unanswered. To address many of these issues, a workshop was organized in Tibet in September 2006 as part of the International Quaternary Union's (INQUA) Commission on Paleoclimate to examine the timing and nature of Late Quaternary mountain glacier advances. The workshop was funded by the US National Science Foundation (NSF), INQUA and the National Science Foundation of China (NSFC), in association with the Institute of Tibetan Plateau Research, the Qinghai Institute of Salt Lakes of the Chinese Academy of Sciences and The China Society of Tibetan Plateau, and the INQUA Working Group on Quaternary Glaciations and Chronology in Monsoonal Asia. The workshop consisted of two parts: 3 days of working sessions and a local field trip in Xining; and a 5-day traverse across the Tibetan Plateau from Xining to Lhasa, which examined a variety of key field sites. The organizing committee included Glenn Thackray (Idaho State University), Lewis A. Owen (University of Cincinnati), Chaolu Yi (Institute of Tibetan Plateau Research, Chinese Academy of Sciences), Shangzhe Zhou (South China Normal University) and Ma Haizhou (Qinghai Institute of Salt Lake, Chinese Academy of Sciences). More than 60 participants attended the meeting, including glacial geologists, geomorphologists and stratigraphers from the USA, China, UK, Australia, New Zealand, Germany, Switzerland, Sweden, and India. Their expertise spanned most of the major mountain regions of the world and covered the disciplines of geomorphology, geochronology, stratigraphy, paleoclimatology and glaciology. 0169-555X/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.geomorph.2008.04.011
The researchers examined the importance of mountain glaciers and deposits as archives of past climatic information and for understanding the nature of landscape evolution in mountain regions. The stratigraphy and paleoclimate component of the workshop built on recent work lead by Ehlers and Gibbard (2004a,b,c) that focused on glacier fluctuations around the last ice-sheet maximum (ca. 21 ka) and the SNOWLINE database project headed by Sandi Harrison and Bryan Mark on equilibrium-line altitudes (ELAs) at the last glacial maximum (Harrison, 2005). The workshop focused on: 1) Assessing the global variability in the timing of Late Pleistocene mountain glacier fluctuations 2) Discussing the links between climate change, glaciation, erosion and uplift, and compilation of data on glacial erosion for mountain regions 3) Initiating new research to fill critical data gaps 4) Building international collaborative relationships, and 5) Examining important glacial stratigraphic sites on the Tibetan plateau. The participants emphasized the importance of mountain glaciers as geomorphic agents and their significant role in denuding landscapes and transferring sediment within and beyond mountain systems. Furthermore, they discussed the important paradigm shifts that have occurred in recent years, specifically how it is becoming increasingly apparent that mountain glacial systems are important in producing significant relief by mountain uplift initiated by denudational unloading, and how glaciers may limit topography (Molnar and England, 1990; Brozovic et al., 1997; Montgomery et al., 2001; Zeitler et al., 2001). They also discussed the significant debate that exists over the importance of glaciers versus other processes, such as fluvial erosion and mass movement, in shaping mountain landscapes. Data from the Himalaya (Brozovic et al., 1997) and the Andes (Montgomery et al., 2001), for example, suggest that glacial erosion limits topography, whereas data from the Cascades (Kelsey et al., 1994; Schmidt and Montgomery, 1995) suggest topography is limited by rock strength or rates of uplift, respectively. Furthermore, in more empirical studies, Spotila et al. (2004) compared rates of denudation to tectonic influx in the Chugach-St. Elias Mountains of southeast Alaska. Long-term rates of denudation were found to be an order of magnitude less than the short-term values set forth by Hallet et al. (1996) who examined sediment yields from glaciated catchments to determine rates of glacial erosion. The questions of what limits topography and the role of glaciers in orographic belts, spatially and temporally, and variations of rates of denudation over time were, therefore, discussed in much detail and were the subject of many presentations at the meeting. In particular, the participants discussed the following questions: 1) What is currently known about the temporal and spatial variability of glacial erosion in mountain regions throughout the world?
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Editorial
2) How do rates of glacial erosion compare with other denudational processes, such as fluvial erosion and mass movement? 3) How important is glacial erosion in forcing uplift by denudational unloading? 4) How important are glaciers and associated processes (for example within the glaciofluvial and periglacial systems) for sediment transfer? 5) How can knowledge of glacial chronologies aid in answering some or all of the above questions? The workshop participants recognized that a stratigraphic and temporal framework is essential to answer these questions and to help quantify and assess the role and importance of mountain glaciers in landscape evolution. Much time was, therefore, given to discussing how robust glacial chronologies could be developed using, for example, newly developed methods, such as, dating with terrestrial cosmogenic nuclide surface exposure and optically stimulated luminescence. A synthesis of Late Quaternary mountain glacial chronologies was compiled and is presented in Thackray et al. (in press). Understanding glacial erosion on longer timescales is a timely topic because it bears directly on the debate over the constraints on maximum relief and altitude found in orogenic mountain belts. The temporal framework, as well as reconstructions of the extent of glaciation, promises to provide important data and insights into the links between glaciation and landscape evolution. The visit to field research areas on the Tibetan Plateau allowed the workshop participants to investigate the nature of glacial records on the Tibetan Plateau, to discuss issues of snowline calculation and dating control for glacial sequences, to discuss influences of monsoonal variation on glacier fluctuations, and to examine issues of glaciation, uplift and erosion. This provided important case studies and an impetus for stimulating more discussion. This special issue of Geomorphology is an outgrowth of the workshop and reflects the discussion and debates on the role of mountain glaciers in landscape evolution that were held at and after the meeting. The first paper in the volume, by Owen et al., provides a foundation for the subsequent papers. It synthesizes many of the recent advances in studying mountain glaciers and highlights how the study of mountain glaciation and geomorphology is becoming increasingly integrated, involving numerous disciplines ranging from geomorphology, glaciology, geochronology, geophysics, meteorology and climatology. The second paper in this volume, by Kaplan et al., presents arguments that glacial erosion can limit the extent of glaciation. The paper provides an insightful example from Patagonia. The authors suggest that a non-climatic relationship exists between glacial modification of the mountains and decreasing the extent of ice, and they discuss processes of landscape development that could have caused the trend. This provides an important hypothesis that might be tested in many other mountainous regions. The papers by Tomkin and MacGregor et al. provide numerical models for glacial erosion in alpine landscapes. Tomkin's numerical model produces landforms that result from climate dependent elevation lowering, similar to what might be expected by a “glacial buzz-saw”, valley overdeepening, terminal moraines, and valley retreat. The model predicts that current rates of sedimentation are higher than the long-term average, and that several tens of thousands of years are required for the landscape to adjust to a change in the dominant erosional forcing. From this modeling, the author suggests that glaciated orogens are unlikely to achieve topographic steady-state over Milankovitch timescales. MacGregor et al.'s modeling addresses how the production of relief at high elevation mountain crests is influenced by glacier dynamics and subglacial erosion, as well as relevant hillslope processes. They provide simulations that show the influence of varying climate and relief development. In the next paper, Fu and Yi examine the relationships between the heights of moraines and lengths of former glaciers in Tibet. They show
that a strong relationship exists between the heights of Holocene lateral moraines and the lengths of glaciers and suggest that this can be used to easily make large-scale regional reconstructions of the extents of former glacier. The study provides an interesting model that might be applied to other regions where large-scale reconstructions are needed. The next paper, by Stroeven et al., applies geomorphological mapping using SRTM topographic data and Landsat 7 ETM+ satellite imagery to evaluate landscape characteristics and patterns, and investigate the relative importance of different erosional processes in the dissection of a region of NE Tibet. The study provides evidence that a small ice sheet existed in the region, and provides a case study of how areas of problematic glacial reconstructions can be examined. The next two papers provide case studies of areas of anomalously high topography. In the first paper, Seong et al. describe the geomorphology of the Mustag Ata and Kongur Shan in eastern most Tibet. They define rates of erosion and show that the style of glaciation has change considerably over time, likely reflecting climate change and topographic developments. In the second paper, Seong et al. examine the glacial and associated geomorphology in the K2 region of the Central Karakoram. They show the strong control of glaciation on topographic development. Both papers emphasize the importance of paraglaciation on landscape development and they provide the first step and a framework to help define numerical models in area of high topography. The last two papers in this special issue provide case studies of glaciated mountains in China. The first paper by Xu and Zhou describes the glacial and fluvial landforms in the Shaluli Mountain of southeastern Tibet. The authors provide evidence for six glacial advances and argue how these are important in producing the current landscape. In the second paper, Zhao et al. describe the glacial geology of the Ateaoyinake River valley in the Tianshan Mountains. They show how electron spin resonance and optically stimulated dating can be successfully used to define the timing of glaciation, which ultimately is essential for defining rates of landscape evolution. Collectively, these papers demonstrate the multifaceted interactions between glaciers and landscapes. They reveal the multiple parts of the glacial system that are important in any robust evaluation of climate– landscape interactions, e.g., erosional influences on subsequent ice accumulation, processes of large-scale glacial landscape development, variability and importance of erosional flux, glacial versus fluvial erosion rates, and variable depositional rates and processes. Much remains to be learned regarding the interplay of glaciation, tectonism, and landscape evolution, but these and other papers illuminate the path toward improved models and understanding. Acknowledgements We thank the numerous colleagues who helped review the papers presented in this special issue and had many discussions with us and the contributors. For funding, we acknowledge the U.S. National Science Foundation (Grant numbers OISE-0536909 and EAR0640378), National Science Foundation of China, Society of China Tibetan Research and the International Quaternary Union (Project 0407). References Brozovic, N., Burbank, D.W., Meigs, A.J., 1997. Climatic limits on landscape development in the Northwestern Himalaya. Science 276, 571–574. Ehlers, J., Gibbard, P. (Eds.), 2004a. Quaternary Glaciations: Extent and Chronologies. Part I: Europe. Developments in Quaternary Science, vol. 2. Ehlers, J., Gibbard, P. (Eds.), 2004b. Quaternary Glaciations: Extent and Chronologies. Part II: North America. Developments in Quaternary Science, vol. 2. Ehlers, J., Gibbard, P. (Eds.), 2004c. Quaternary Glaciations: Extent and Chronologies. Part III: South America, Asia, Africa, Australia, Antarctica. Developments in Quaternary Science, vol. 2. 380 pp. Harrison, S. (Ed.), 2005. Tropical Snowlines at the Last Glacial Maximum. Quaternary International, vol. 138/139.
Editorial Hallet, B., Hunter, L., Bogen, J., 1996. Rates of erosion and sediment evacuation by glaciers: a review of field data and their implications. Global and Planetary Change 12, 213–235. Kelsey, H.M., Engebretson, D.C., Mitchel, C.E., Ticknor, R.L., 1994. Topographic form of the Coast Ranges of the Cascadia Margin in relation to coastal uplift rates and plate subduction. Journal of Geophysical Research 99 (B6), 12,245–12,255. Molnar, P., England, P., 1990. Late Cenozoic uplift of mountain ranges and global climate change: chicken or egg? Nature 346, 29–34. Montgomery, D.R., Balco, G., Willet, S.D., 2001. Climate, tectonics, and the morphology of the Andes. Geology 29, 579–582. Schmidt, K.M., Montgomery, D.R., 1995. Limits to relief. Science, 270, 617–620. Spotila, J.A., Buscher, J.T., Meigs, A.J., Reiners, P.W., 2004. Long-term erosion of active mountain belts: example of the Chugach-St. Elias Range, Alaska. Geology 32, 501–504. Thackray, G., Owen, L.A., Yi, C. in press. Mountain glacier chronologies. Journal of Quaternary Science. Zeitler, P.K., Meltzer, A.S., Koons, P.O., Craw, D., Hallet, B., Chamberlain, C.P., Kidd, W.S.F., Park, S.K., Seeber, L., 2001. Erosion, Himalayan geodynamics, and the geomorphology of metamorphism. GSA Today 11, 4–9.
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Lewis A. Owen Department of Geology, University of Cincinnati, Cincinnati, OH 45040, United States Corresponding author. Tel.: +1 513 5564203. E-mail address: [email protected]. Glenn Thackray Department of Geosciences, Idaho State University, Pocatello ID 83209, United States Chaolu Yi Institute for Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100085, China
Contents lists available at ScienceDirect
Geomorphology j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / g e o m o r p h
Editorial
Mountain glaciation and landscape evolution
Keywords: Mountain glaciation Glaciers Geochronology Uplift Erosion
Mountain glaciers are important geomorphic agents and they play a significant role in denuding landscapes and transferring sediment within and beyond mountain systems. In recent years an important paradigm shift occurred from considering mountain glacial systems as simply responding to climate change within a region that was tectonically uplifted to considering mountain glaciers as agents that help drive mountain uplift, essentially by denudational unloading, and as controls that help limit topography. Significant debate exists over the importance of glaciers versus other processes, such as fluvial erosion and mass movement, in shaping mountain landscapes. Furthermore, long-term rates of denudation are found to be an order of magnitude less than the short-term values in many regions where sediment yields from glaciated catchments have been used to determine rates of glacial erosion. Currently, the questions of what limits topography and of what role glaciers play in orographic belts, spatially and temporally, and of how rates of denudation vary over time, remain unanswered. To address many of these issues, a workshop was organized in Tibet in September 2006 as part of the International Quaternary Union's (INQUA) Commission on Paleoclimate to examine the timing and nature of Late Quaternary mountain glacier advances. The workshop was funded by the US National Science Foundation (NSF), INQUA and the National Science Foundation of China (NSFC), in association with the Institute of Tibetan Plateau Research, the Qinghai Institute of Salt Lakes of the Chinese Academy of Sciences and The China Society of Tibetan Plateau, and the INQUA Working Group on Quaternary Glaciations and Chronology in Monsoonal Asia. The workshop consisted of two parts: 3 days of working sessions and a local field trip in Xining; and a 5-day traverse across the Tibetan Plateau from Xining to Lhasa, which examined a variety of key field sites. The organizing committee included Glenn Thackray (Idaho State University), Lewis A. Owen (University of Cincinnati), Chaolu Yi (Institute of Tibetan Plateau Research, Chinese Academy of Sciences), Shangzhe Zhou (South China Normal University) and Ma Haizhou (Qinghai Institute of Salt Lake, Chinese Academy of Sciences). More than 60 participants attended the meeting, including glacial geologists, geomorphologists and stratigraphers from the USA, China, UK, Australia, New Zealand, Germany, Switzerland, Sweden, and India. Their expertise spanned most of the major mountain regions of the world and covered the disciplines of geomorphology, geochronology, stratigraphy, paleoclimatology and glaciology. 0169-555X/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.geomorph.2008.04.011
The researchers examined the importance of mountain glaciers and deposits as archives of past climatic information and for understanding the nature of landscape evolution in mountain regions. The stratigraphy and paleoclimate component of the workshop built on recent work lead by Ehlers and Gibbard (2004a,b,c) that focused on glacier fluctuations around the last ice-sheet maximum (ca. 21 ka) and the SNOWLINE database project headed by Sandi Harrison and Bryan Mark on equilibrium-line altitudes (ELAs) at the last glacial maximum (Harrison, 2005). The workshop focused on: 1) Assessing the global variability in the timing of Late Pleistocene mountain glacier fluctuations 2) Discussing the links between climate change, glaciation, erosion and uplift, and compilation of data on glacial erosion for mountain regions 3) Initiating new research to fill critical data gaps 4) Building international collaborative relationships, and 5) Examining important glacial stratigraphic sites on the Tibetan plateau. The participants emphasized the importance of mountain glaciers as geomorphic agents and their significant role in denuding landscapes and transferring sediment within and beyond mountain systems. Furthermore, they discussed the important paradigm shifts that have occurred in recent years, specifically how it is becoming increasingly apparent that mountain glacial systems are important in producing significant relief by mountain uplift initiated by denudational unloading, and how glaciers may limit topography (Molnar and England, 1990; Brozovic et al., 1997; Montgomery et al., 2001; Zeitler et al., 2001). They also discussed the significant debate that exists over the importance of glaciers versus other processes, such as fluvial erosion and mass movement, in shaping mountain landscapes. Data from the Himalaya (Brozovic et al., 1997) and the Andes (Montgomery et al., 2001), for example, suggest that glacial erosion limits topography, whereas data from the Cascades (Kelsey et al., 1994; Schmidt and Montgomery, 1995) suggest topography is limited by rock strength or rates of uplift, respectively. Furthermore, in more empirical studies, Spotila et al. (2004) compared rates of denudation to tectonic influx in the Chugach-St. Elias Mountains of southeast Alaska. Long-term rates of denudation were found to be an order of magnitude less than the short-term values set forth by Hallet et al. (1996) who examined sediment yields from glaciated catchments to determine rates of glacial erosion. The questions of what limits topography and the role of glaciers in orographic belts, spatially and temporally, and variations of rates of denudation over time were, therefore, discussed in much detail and were the subject of many presentations at the meeting. In particular, the participants discussed the following questions: 1) What is currently known about the temporal and spatial variability of glacial erosion in mountain regions throughout the world?
156
Editorial
2) How do rates of glacial erosion compare with other denudational processes, such as fluvial erosion and mass movement? 3) How important is glacial erosion in forcing uplift by denudational unloading? 4) How important are glaciers and associated processes (for example within the glaciofluvial and periglacial systems) for sediment transfer? 5) How can knowledge of glacial chronologies aid in answering some or all of the above questions? The workshop participants recognized that a stratigraphic and temporal framework is essential to answer these questions and to help quantify and assess the role and importance of mountain glaciers in landscape evolution. Much time was, therefore, given to discussing how robust glacial chronologies could be developed using, for example, newly developed methods, such as, dating with terrestrial cosmogenic nuclide surface exposure and optically stimulated luminescence. A synthesis of Late Quaternary mountain glacial chronologies was compiled and is presented in Thackray et al. (in press). Understanding glacial erosion on longer timescales is a timely topic because it bears directly on the debate over the constraints on maximum relief and altitude found in orogenic mountain belts. The temporal framework, as well as reconstructions of the extent of glaciation, promises to provide important data and insights into the links between glaciation and landscape evolution. The visit to field research areas on the Tibetan Plateau allowed the workshop participants to investigate the nature of glacial records on the Tibetan Plateau, to discuss issues of snowline calculation and dating control for glacial sequences, to discuss influences of monsoonal variation on glacier fluctuations, and to examine issues of glaciation, uplift and erosion. This provided important case studies and an impetus for stimulating more discussion. This special issue of Geomorphology is an outgrowth of the workshop and reflects the discussion and debates on the role of mountain glaciers in landscape evolution that were held at and after the meeting. The first paper in the volume, by Owen et al., provides a foundation for the subsequent papers. It synthesizes many of the recent advances in studying mountain glaciers and highlights how the study of mountain glaciation and geomorphology is becoming increasingly integrated, involving numerous disciplines ranging from geomorphology, glaciology, geochronology, geophysics, meteorology and climatology. The second paper in this volume, by Kaplan et al., presents arguments that glacial erosion can limit the extent of glaciation. The paper provides an insightful example from Patagonia. The authors suggest that a non-climatic relationship exists between glacial modification of the mountains and decreasing the extent of ice, and they discuss processes of landscape development that could have caused the trend. This provides an important hypothesis that might be tested in many other mountainous regions. The papers by Tomkin and MacGregor et al. provide numerical models for glacial erosion in alpine landscapes. Tomkin's numerical model produces landforms that result from climate dependent elevation lowering, similar to what might be expected by a “glacial buzz-saw”, valley overdeepening, terminal moraines, and valley retreat. The model predicts that current rates of sedimentation are higher than the long-term average, and that several tens of thousands of years are required for the landscape to adjust to a change in the dominant erosional forcing. From this modeling, the author suggests that glaciated orogens are unlikely to achieve topographic steady-state over Milankovitch timescales. MacGregor et al.'s modeling addresses how the production of relief at high elevation mountain crests is influenced by glacier dynamics and subglacial erosion, as well as relevant hillslope processes. They provide simulations that show the influence of varying climate and relief development. In the next paper, Fu and Yi examine the relationships between the heights of moraines and lengths of former glaciers in Tibet. They show
that a strong relationship exists between the heights of Holocene lateral moraines and the lengths of glaciers and suggest that this can be used to easily make large-scale regional reconstructions of the extents of former glacier. The study provides an interesting model that might be applied to other regions where large-scale reconstructions are needed. The next paper, by Stroeven et al., applies geomorphological mapping using SRTM topographic data and Landsat 7 ETM+ satellite imagery to evaluate landscape characteristics and patterns, and investigate the relative importance of different erosional processes in the dissection of a region of NE Tibet. The study provides evidence that a small ice sheet existed in the region, and provides a case study of how areas of problematic glacial reconstructions can be examined. The next two papers provide case studies of areas of anomalously high topography. In the first paper, Seong et al. describe the geomorphology of the Mustag Ata and Kongur Shan in eastern most Tibet. They define rates of erosion and show that the style of glaciation has change considerably over time, likely reflecting climate change and topographic developments. In the second paper, Seong et al. examine the glacial and associated geomorphology in the K2 region of the Central Karakoram. They show the strong control of glaciation on topographic development. Both papers emphasize the importance of paraglaciation on landscape development and they provide the first step and a framework to help define numerical models in area of high topography. The last two papers in this special issue provide case studies of glaciated mountains in China. The first paper by Xu and Zhou describes the glacial and fluvial landforms in the Shaluli Mountain of southeastern Tibet. The authors provide evidence for six glacial advances and argue how these are important in producing the current landscape. In the second paper, Zhao et al. describe the glacial geology of the Ateaoyinake River valley in the Tianshan Mountains. They show how electron spin resonance and optically stimulated dating can be successfully used to define the timing of glaciation, which ultimately is essential for defining rates of landscape evolution. Collectively, these papers demonstrate the multifaceted interactions between glaciers and landscapes. They reveal the multiple parts of the glacial system that are important in any robust evaluation of climate– landscape interactions, e.g., erosional influences on subsequent ice accumulation, processes of large-scale glacial landscape development, variability and importance of erosional flux, glacial versus fluvial erosion rates, and variable depositional rates and processes. Much remains to be learned regarding the interplay of glaciation, tectonism, and landscape evolution, but these and other papers illuminate the path toward improved models and understanding. Acknowledgements We thank the numerous colleagues who helped review the papers presented in this special issue and had many discussions with us and the contributors. For funding, we acknowledge the U.S. National Science Foundation (Grant numbers OISE-0536909 and EAR0640378), National Science Foundation of China, Society of China Tibetan Research and the International Quaternary Union (Project 0407). References Brozovic, N., Burbank, D.W., Meigs, A.J., 1997. Climatic limits on landscape development in the Northwestern Himalaya. Science 276, 571–574. Ehlers, J., Gibbard, P. (Eds.), 2004a. Quaternary Glaciations: Extent and Chronologies. Part I: Europe. Developments in Quaternary Science, vol. 2. Ehlers, J., Gibbard, P. (Eds.), 2004b. Quaternary Glaciations: Extent and Chronologies. Part II: North America. Developments in Quaternary Science, vol. 2. Ehlers, J., Gibbard, P. (Eds.), 2004c. Quaternary Glaciations: Extent and Chronologies. Part III: South America, Asia, Africa, Australia, Antarctica. Developments in Quaternary Science, vol. 2. 380 pp. Harrison, S. (Ed.), 2005. Tropical Snowlines at the Last Glacial Maximum. Quaternary International, vol. 138/139.
Editorial Hallet, B., Hunter, L., Bogen, J., 1996. Rates of erosion and sediment evacuation by glaciers: a review of field data and their implications. Global and Planetary Change 12, 213–235. Kelsey, H.M., Engebretson, D.C., Mitchel, C.E., Ticknor, R.L., 1994. Topographic form of the Coast Ranges of the Cascadia Margin in relation to coastal uplift rates and plate subduction. Journal of Geophysical Research 99 (B6), 12,245–12,255. Molnar, P., England, P., 1990. Late Cenozoic uplift of mountain ranges and global climate change: chicken or egg? Nature 346, 29–34. Montgomery, D.R., Balco, G., Willet, S.D., 2001. Climate, tectonics, and the morphology of the Andes. Geology 29, 579–582. Schmidt, K.M., Montgomery, D.R., 1995. Limits to relief. Science, 270, 617–620. Spotila, J.A., Buscher, J.T., Meigs, A.J., Reiners, P.W., 2004. Long-term erosion of active mountain belts: example of the Chugach-St. Elias Range, Alaska. Geology 32, 501–504. Thackray, G., Owen, L.A., Yi, C. in press. Mountain glacier chronologies. Journal of Quaternary Science. Zeitler, P.K., Meltzer, A.S., Koons, P.O., Craw, D., Hallet, B., Chamberlain, C.P., Kidd, W.S.F., Park, S.K., Seeber, L., 2001. Erosion, Himalayan geodynamics, and the geomorphology of metamorphism. GSA Today 11, 4–9.
157
Lewis A. Owen Department of Geology, University of Cincinnati, Cincinnati, OH 45040, United States Corresponding author. Tel.: +1 513 5564203. E-mail address: [email protected]. Glenn Thackray Department of Geosciences, Idaho State University, Pocatello ID 83209, United States Chaolu Yi Institute for Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100085, China