Pub Date : 2020-01-02DOI: 10.1080/04353676.2019.1702809
K. Lidmar-Bergström
ABSTRACT This paper presents the result of my research in Sweden and my view on the relationships between physical geography (here mainly geomorphology) and geology. I developed a method for identification and mapping denudation surfaces formed in the Precambrian basement. South Sweden turned out to be a key area with cover rocks of different age directly on the basement. The relief differences in the basement are connected to the different sedimentary covers with a flat and inclined sub-Cambrian surface and a hilly and inclined sub-Cretaceous surface. The crosscutting horizontal South Småland Plain was classified as a peneplain, as it is a surface graded to a distinct base level. Besides the basement forms and remnant cover rocks, saprolite remnants are important for the identification of denudation surfaces. The mapping method was ultimately labeled Stratigraphic Landscape Analysis (SLA) and used for conclusion on tectonics (uplift/subsidence and faulting). I obtained, as a physical geographer, a broad holistic knowledge on the relief differentiation of the basement rocks of Fennoscandia and on Swedish regional geology. This gave me the tool to identify denudation surfaces with the aid of the new digital elevation data and new geological knowledge of the surrounding continental shelf. The Swedish knowledge on the relationships between relief in the basement and its cover rocks is unique in the world. Maybe the relationship between denudation surfaces, cover rocks and tectonics ought to be a part of geology. Results of measurements, by different new techniques, are nowadays often analyzed based on hypotheses/theories. Observations of field conditions have become difficult to perform both within geology and geomorphology and seem to be considered as unscientific. Further, regional analysis, typical for geography, does not exist anymore.
{"title":"The major landforms of the bedrock of Sweden – with a view on the relationships between physical geography and geology","authors":"K. Lidmar-Bergström","doi":"10.1080/04353676.2019.1702809","DOIUrl":"https://doi.org/10.1080/04353676.2019.1702809","url":null,"abstract":"ABSTRACT This paper presents the result of my research in Sweden and my view on the relationships between physical geography (here mainly geomorphology) and geology. I developed a method for identification and mapping denudation surfaces formed in the Precambrian basement. South Sweden turned out to be a key area with cover rocks of different age directly on the basement. The relief differences in the basement are connected to the different sedimentary covers with a flat and inclined sub-Cambrian surface and a hilly and inclined sub-Cretaceous surface. The crosscutting horizontal South Småland Plain was classified as a peneplain, as it is a surface graded to a distinct base level. Besides the basement forms and remnant cover rocks, saprolite remnants are important for the identification of denudation surfaces. The mapping method was ultimately labeled Stratigraphic Landscape Analysis (SLA) and used for conclusion on tectonics (uplift/subsidence and faulting). I obtained, as a physical geographer, a broad holistic knowledge on the relief differentiation of the basement rocks of Fennoscandia and on Swedish regional geology. This gave me the tool to identify denudation surfaces with the aid of the new digital elevation data and new geological knowledge of the surrounding continental shelf. The Swedish knowledge on the relationships between relief in the basement and its cover rocks is unique in the world. Maybe the relationship between denudation surfaces, cover rocks and tectonics ought to be a part of geology. Results of measurements, by different new techniques, are nowadays often analyzed based on hypotheses/theories. Observations of field conditions have become difficult to perform both within geology and geomorphology and seem to be considered as unscientific. Further, regional analysis, typical for geography, does not exist anymore.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"51 1","pages":"1 - 11"},"PeriodicalIF":1.5,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82473887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-02DOI: 10.1080/04353676.2020.1715124
J. Kavan
ABSTRACT Glaciers in central Svalbard are retreating since their Little Ice Age maximum, dated in the area to around 1900. Past areal extent of glaciers can confidently be reconstructed based on end moraine position. However, reconstructions of thickness and volume of glaciers remain relatively more complicated and uncertain. In this study, past changes in thickness and volume of the Ferdinand Glacier was reconstructed based on Structure-from-Motion techniques and field dGPS measurements in combination with analysis of historic photos from 1908 and aerial photos from 1938. According to the comparison of the historic and recent photograph, the 1908 glacier front height was estimated to 50 m and the glacier volume to 91.5 mil m3 and the 1938 glacier volume estimated to 76.1 mil m3, in comparison to 6.29 mil m3 in 2014. This means more than 90% loss of volume since 1938. Melting of the glacier in the first half of the twentieth century resulted in thinning and lowering of the glacier surface together with substantial ice volume loss, whereas the areal extent was almost not affected. Considering the 2014 mean ice thickness, together with ongoing climate warming, it is likely that the Ferdinand Glacier will completely disappear within the next 30 years.
斯瓦尔巴中部的冰川自1900年左右的小冰期以来一直在退缩。根据终末冰碛位置可以很有把握地重建冰川过去的面积范围。然而，冰川厚度和体积的重建仍然相对复杂和不确定。本研究基于结构-运动技术和野外dGPS测量，结合对1908年历史照片和1938年航空照片的分析，重建了费迪南德冰川过去的厚度和体积变化。根据历史和近期照片的对比，估计1908年冰川锋高为50 m，冰川体积为91.5 mil m3, 1938年冰川体积为76.1 mil m3，而2014年为6.29 mil m3。这意味着自1938年以来损失了90%以上的交易量。20世纪上半叶的冰川融化导致冰川表面变薄和降低，冰量大量减少，而面积范围几乎没有受到影响。考虑到2014年的平均冰厚，再加上持续的气候变暖，费迪南德冰川很可能在未来30年内完全消失。
{"title":"Early twentieth century evolution of Ferdinand glacier, Svalbard, based on historic photographs and structure-from-motion technique","authors":"J. Kavan","doi":"10.1080/04353676.2020.1715124","DOIUrl":"https://doi.org/10.1080/04353676.2020.1715124","url":null,"abstract":"ABSTRACT Glaciers in central Svalbard are retreating since their Little Ice Age maximum, dated in the area to around 1900. Past areal extent of glaciers can confidently be reconstructed based on end moraine position. However, reconstructions of thickness and volume of glaciers remain relatively more complicated and uncertain. In this study, past changes in thickness and volume of the Ferdinand Glacier was reconstructed based on Structure-from-Motion techniques and field dGPS measurements in combination with analysis of historic photos from 1908 and aerial photos from 1938. According to the comparison of the historic and recent photograph, the 1908 glacier front height was estimated to 50 m and the glacier volume to 91.5 mil m3 and the 1938 glacier volume estimated to 76.1 mil m3, in comparison to 6.29 mil m3 in 2014. This means more than 90% loss of volume since 1938. Melting of the glacier in the first half of the twentieth century resulted in thinning and lowering of the glacier surface together with substantial ice volume loss, whereas the areal extent was almost not affected. Considering the 2014 mean ice thickness, together with ongoing climate warming, it is likely that the Ferdinand Glacier will completely disappear within the next 30 years.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"112 1","pages":"57 - 67"},"PeriodicalIF":1.5,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80824012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-02DOI: 10.1080/04353676.2020.1711665
Antoine Boisson, M. Allard
ABSTRACT Boulder barricades are poorly documented Holocene coastal landforms of Arctic and Subarctic regions. To understand the terrain factors and coastal processes explaining the occurrences of boulder barricades, we mapped and described these periglacial landforms along the emerging hypertidal coast of Ungava Bay, in Nunavik, northern Quebec, Canada. This study examines the spatial distribution as well as the different types and configurations of boulder barricades, and identifies and discusses the formation processes of these ridges, which are affected by the ongoing glacial isostatic adjustment (GIA) process. We distinguish four types of ice-formed boulder ridges: low-tide-, intertidal-, high-tide- and raised boulder barricades. Our results highlight the importance of specific terrain factors (coastal configurations, intertidal and backshore slopes, widths of intertidal zones, susceptibility to coastal erosion) and related coastal processes (ice-pushing and ice-rafting intensified by strong tidal currents), forming these different types of barricades. Due to the GIA process, this coastal region is characterized by a large number of evolutionary sequences (i.e. flights) of boulder barricades, from the intertidal zone to the emerged landscape. These sea-ice-related landforms have significant effects on the coastal geomorphology of the Ungava Bay region by successively enclosing and isolating many ponds and lakes.
{"title":"Boulder barricades in an emerging hypertidal environment: the case of Ungava Bay, northern Quebec, Canada","authors":"Antoine Boisson, M. Allard","doi":"10.1080/04353676.2020.1711665","DOIUrl":"https://doi.org/10.1080/04353676.2020.1711665","url":null,"abstract":"ABSTRACT Boulder barricades are poorly documented Holocene coastal landforms of Arctic and Subarctic regions. To understand the terrain factors and coastal processes explaining the occurrences of boulder barricades, we mapped and described these periglacial landforms along the emerging hypertidal coast of Ungava Bay, in Nunavik, northern Quebec, Canada. This study examines the spatial distribution as well as the different types and configurations of boulder barricades, and identifies and discusses the formation processes of these ridges, which are affected by the ongoing glacial isostatic adjustment (GIA) process. We distinguish four types of ice-formed boulder ridges: low-tide-, intertidal-, high-tide- and raised boulder barricades. Our results highlight the importance of specific terrain factors (coastal configurations, intertidal and backshore slopes, widths of intertidal zones, susceptibility to coastal erosion) and related coastal processes (ice-pushing and ice-rafting intensified by strong tidal currents), forming these different types of barricades. Due to the GIA process, this coastal region is characterized by a large number of evolutionary sequences (i.e. flights) of boulder barricades, from the intertidal zone to the emerged landscape. These sea-ice-related landforms have significant effects on the coastal geomorphology of the Ungava Bay region by successively enclosing and isolating many ponds and lakes.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"24 1","pages":"33 - 56"},"PeriodicalIF":1.5,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75766489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-01-02DOI: 10.1080/04353676.2020.1723984
M. Hellqvist, M. Hättestrand, E. Norström, Elisabeth Almgren, Jenny Johansson, Ragnheiður Traustadóttir
ABSTRACT We present an overview of the local environmental development of the valley of Hjaltadalur, situated in Skagafjörður, northern Iceland. The aim of this study is to increase the knowledge about the valley region before and during human settlement in the ninth century. Four mires were investigated after which the Viðvík peat bog was selected as the main site for evaluating changes in climate and landscape. The master core from Viðvík (V-325) was dated and studied further through sediment analysis, loss-on-ignition (LOI), and pollen analysis. According to the age-depth model, based on three radiocarbon dates and analysis of two tephra layers, the 325 cm long Viðvík core comprises approximately 5500 years. In the pollen percentage record, there is a decrease in birch (Betula) and an increase in grass (Poaceae) in the central part of the core, between Hekla 3 horizon at c. 2800 BP and the next dated level at c. 2000 BP. This change corresponds well with previously outlined environmental fluctuations, showing a transition from warm and dry climate to cool and humid climate at this time. Human activity is mainly reflected by a distinct peak in Lactucae pollen in the uppermost part of the core. This change in vegetation corresponds with earlier studies, showing that the vegetation changed dramatically after the colonization of Iceland in the ninth century (during Landnám period, 870–930 AD). The present study shows that a decline in birch started well before human settlement, although the subsequent Viking Age and later settlements continued the deforestation trend.
{"title":"Environment and climate change during the late Holocene in Hjaltadalur, Skagafjörður, northern Iceland","authors":"M. Hellqvist, M. Hättestrand, E. Norström, Elisabeth Almgren, Jenny Johansson, Ragnheiður Traustadóttir","doi":"10.1080/04353676.2020.1723984","DOIUrl":"https://doi.org/10.1080/04353676.2020.1723984","url":null,"abstract":"ABSTRACT We present an overview of the local environmental development of the valley of Hjaltadalur, situated in Skagafjörður, northern Iceland. The aim of this study is to increase the knowledge about the valley region before and during human settlement in the ninth century. Four mires were investigated after which the Viðvík peat bog was selected as the main site for evaluating changes in climate and landscape. The master core from Viðvík (V-325) was dated and studied further through sediment analysis, loss-on-ignition (LOI), and pollen analysis. According to the age-depth model, based on three radiocarbon dates and analysis of two tephra layers, the 325 cm long Viðvík core comprises approximately 5500 years. In the pollen percentage record, there is a decrease in birch (Betula) and an increase in grass (Poaceae) in the central part of the core, between Hekla 3 horizon at c. 2800 BP and the next dated level at c. 2000 BP. This change corresponds well with previously outlined environmental fluctuations, showing a transition from warm and dry climate to cool and humid climate at this time. Human activity is mainly reflected by a distinct peak in Lactucae pollen in the uppermost part of the core. This change in vegetation corresponds with earlier studies, showing that the vegetation changed dramatically after the colonization of Iceland in the ninth century (during Landnám period, 870–930 AD). The present study shows that a decline in birch started well before human settlement, although the subsequent Viking Age and later settlements continued the deforestation trend.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"37 1","pages":"68 - 82"},"PeriodicalIF":1.5,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75377674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-02DOI: 10.1080/04353676.2019.1670952
L. Mallinson, D. Swift, A. Sole
ABSTRACT Proglacial icings (also known as naled or aufeis) are frequently observed in the forefields of polar glaciers. Their formation has been ascribed to the refreezing of upwelling groundwater that has originated from subglacial melt, and thus the presence of icings has been used as evidence of polythermal glacier regime. We provide an updated analysis of icing occurrence in Svalbard and test the utility of icings as an indicator of thermal regime by comparing icing presence with: (1) mean glacier thickness, as a proxy for present thermal regime; and (2) evidence of past surge activity, which is an indicator of past thermal regime. A total of 279 icings were identified from TopoSvalbard imagery covering the period 2008-2012, of which 143 corresponded to icings identified by a previous study of aerial photographs from 1990. Only 46% of icings observed in 2008–2012 were found to occur at glaciers with thicknesses consistent with a polythermal regime, meaning a large proportion were associated with glaciers predicted to be of a cold or transitional thermal regime. As a result, icing presence alone may be an unsuitable indicator of glacier regime. We further found that, of the 279 glaciers with icings, 63% of cold-based glaciers and 64% of transitional glaciers were associated with evidence of surge activity. We therefore suggest that proglacial icing formation in Svalbard may reflect historical (rather than present) thermal regime, and that icings possibly originate from groundwater effusion from subglacial taliks that persist for decades following glacier thinning and associated regime change.
{"title":"Proglacial icings as indicators of glacier thermal regime: ice thickness changes and icing occurrence in Svalbard","authors":"L. Mallinson, D. Swift, A. Sole","doi":"10.1080/04353676.2019.1670952","DOIUrl":"https://doi.org/10.1080/04353676.2019.1670952","url":null,"abstract":"ABSTRACT Proglacial icings (also known as naled or aufeis) are frequently observed in the forefields of polar glaciers. Their formation has been ascribed to the refreezing of upwelling groundwater that has originated from subglacial melt, and thus the presence of icings has been used as evidence of polythermal glacier regime. We provide an updated analysis of icing occurrence in Svalbard and test the utility of icings as an indicator of thermal regime by comparing icing presence with: (1) mean glacier thickness, as a proxy for present thermal regime; and (2) evidence of past surge activity, which is an indicator of past thermal regime. A total of 279 icings were identified from TopoSvalbard imagery covering the period 2008-2012, of which 143 corresponded to icings identified by a previous study of aerial photographs from 1990. Only 46% of icings observed in 2008–2012 were found to occur at glaciers with thicknesses consistent with a polythermal regime, meaning a large proportion were associated with glaciers predicted to be of a cold or transitional thermal regime. As a result, icing presence alone may be an unsuitable indicator of glacier regime. We further found that, of the 279 glaciers with icings, 63% of cold-based glaciers and 64% of transitional glaciers were associated with evidence of surge activity. We therefore suggest that proglacial icing formation in Svalbard may reflect historical (rather than present) thermal regime, and that icings possibly originate from groundwater effusion from subglacial taliks that persist for decades following glacier thinning and associated regime change.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"42 1","pages":"334 - 349"},"PeriodicalIF":1.5,"publicationDate":"2019-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89837399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-10-02DOI: 10.1080/04353676.2019.1675465
J. Cortés‐Ramos, H. Delgado-Granados, C. Huggel, G. Ontiveros-González
ABSTRACT The evolution of Mexican glaciers (19° N) in the climate context is poorly understood despite these glaciers are important indicators of regional climate change. The detailed patterns of glacier recession since the Little Ice Age (LIA) have exacerbated during the past years and decades. Their relationship to local and regional climate change needs further analysis. This study compares the changes of the largest glacier in Mexico, Glaciar Norte (GN), on Citlaltépetl Volcano with temperature, precipitation, and surface energy balance variations that were considered as part of climate forcing. Area, length, elevation, equilibrium line altitude (ELA), and thickness were calculated from historical and satellite data sets and a high-resolution Digital Elevation Model. The results showed that during the 1990s, prevailing warm and variable dry conditions enhanced the glacier retreat, triggering the disappearance of Jamapa glacier tongue. The glacier length has changed at the rate of −20.7 m a−1 since 1958. ELA varied from 4999 m a.s.l. in 1958–5228 m a.s.l. in 2017. A short period of snow accumulation from 2007 to 2009 was found when the annual temperature over GN showed a noticeable negative trend similar to that for the accumulated surface energy balance. The surface energy balance was conclusive on the response of GN to stability or accumulation periods. Finally, the long-term variation of temperature was the only factor found forcing the glacier retreat. Assuming that the retreat rate (−0.02 km a−1) and climate tendencies remained constant (0.1°C/decade), GN could disappear towards the middle of the twenty-first century.
尽管墨西哥冰川(19°N)是区域气候变化的重要指标，但人们对这些冰川在气候背景下的演变知之甚少。自小冰期(LIA)以来，冰川衰退的详细模式在过去几年和几十年中有所加剧。它们与当地和区域气候变化的关系需要进一步分析。本研究比较了墨西哥最大的冰川，citlaltsamupel火山上的Glaciar Norte (GN)的变化与温度、降水和地表能量平衡的变化，这些变化被认为是气候强迫的一部分。根据历史和卫星数据集以及高分辨率数字高程模型计算了面积、长度、高程、平衡线高度(ELA)和厚度。结果表明，20世纪90年代，普遍的温暖和变干条件加剧了冰川退缩，引发了Jamapa冰舌的消失。自1958年以来，冰川长度以- 20.7 m a - 1的速率变化。ELA从1958年的4999 m a.s.l.到2017年的5228 m a.s.l.不等。2007 - 2009年，GN上空的年气温与累积的地表能量平衡呈明显的负趋势，出现了短暂的积雪期。地表能量平衡决定了GN对稳定期或积累期的响应。最后，温度的长期变化是人们发现的迫使冰川退缩的唯一因素。假设退缩速率(- 0.02 km a - 1)和气候趋势保持不变(0.1°C/ 10年)，GN可能在21世纪中叶消失。
{"title":"Evolution of the largest glacier in Mexico (Glaciar Norte) since the 50s: factors driving glacier retreat*","authors":"J. Cortés‐Ramos, H. Delgado-Granados, C. Huggel, G. Ontiveros-González","doi":"10.1080/04353676.2019.1675465","DOIUrl":"https://doi.org/10.1080/04353676.2019.1675465","url":null,"abstract":"ABSTRACT The evolution of Mexican glaciers (19° N) in the climate context is poorly understood despite these glaciers are important indicators of regional climate change. The detailed patterns of glacier recession since the Little Ice Age (LIA) have exacerbated during the past years and decades. Their relationship to local and regional climate change needs further analysis. This study compares the changes of the largest glacier in Mexico, Glaciar Norte (GN), on Citlaltépetl Volcano with temperature, precipitation, and surface energy balance variations that were considered as part of climate forcing. Area, length, elevation, equilibrium line altitude (ELA), and thickness were calculated from historical and satellite data sets and a high-resolution Digital Elevation Model. The results showed that during the 1990s, prevailing warm and variable dry conditions enhanced the glacier retreat, triggering the disappearance of Jamapa glacier tongue. The glacier length has changed at the rate of −20.7 m a−1 since 1958. ELA varied from 4999 m a.s.l. in 1958–5228 m a.s.l. in 2017. A short period of snow accumulation from 2007 to 2009 was found when the annual temperature over GN showed a noticeable negative trend similar to that for the accumulated surface energy balance. The surface energy balance was conclusive on the response of GN to stability or accumulation periods. Finally, the long-term variation of temperature was the only factor found forcing the glacier retreat. Assuming that the retreat rate (−0.02 km a−1) and climate tendencies remained constant (0.1°C/decade), GN could disappear towards the middle of the twenty-first century.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"10 1","pages":"350 - 373"},"PeriodicalIF":1.5,"publicationDate":"2019-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84743172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-09-28DOI: 10.1080/04353676.2019.1670950
T. Wagner, Marcus Pauritsch, C. Mayaud, A. Kellerer‐Pirklbauer, Felix Thalheim, G. Winkler
ABSTRACT Coarse blocky material is known to have a ground cooling effect compared to other types of unconsolidated surface material, which may have an influence on spatial distribution and conservation of permafrost. In the light of climate warming, this effect may retard permafrost degradation or exert prolonged ground cooling in general. To contribute to a better understanding of this ground cooling effect and potential influencing factors, the thermal regime of blocky surface layers of two comparable nearby relict rock glaciers with opposing aspects was investigated. Air, surface and shallow ground temperature at 1 m depth were continuously measured over a four-year period at nine locations distributed over two rock glaciers. The blocky surface layer of the SW-exposed rock glacier exhibits lower and more heterogeneous temperatures than the NE-oriented despite a higher potential solar radiation. The data suggest a thinner or more discontinuous seasonal snow cover at the SW-exposed rock glacier, causing a more efficient winter cooling. The importance of air flow driven heat transfer as a source of cooling is supported by the data. Results illustrate thermal heterogeneities within blocky layers and the importance of the seasonal snow cover pattern in addition to topography and microclimatic variability in high relief terrain is hypothesized.
{"title":"Controlling factors of microclimate in blocky surface layers of two nearby relict rock glaciers (Niedere Tauern Range, Austria)","authors":"T. Wagner, Marcus Pauritsch, C. Mayaud, A. Kellerer‐Pirklbauer, Felix Thalheim, G. Winkler","doi":"10.1080/04353676.2019.1670950","DOIUrl":"https://doi.org/10.1080/04353676.2019.1670950","url":null,"abstract":"ABSTRACT Coarse blocky material is known to have a ground cooling effect compared to other types of unconsolidated surface material, which may have an influence on spatial distribution and conservation of permafrost. In the light of climate warming, this effect may retard permafrost degradation or exert prolonged ground cooling in general. To contribute to a better understanding of this ground cooling effect and potential influencing factors, the thermal regime of blocky surface layers of two comparable nearby relict rock glaciers with opposing aspects was investigated. Air, surface and shallow ground temperature at 1 m depth were continuously measured over a four-year period at nine locations distributed over two rock glaciers. The blocky surface layer of the SW-exposed rock glacier exhibits lower and more heterogeneous temperatures than the NE-oriented despite a higher potential solar radiation. The data suggest a thinner or more discontinuous seasonal snow cover at the SW-exposed rock glacier, causing a more efficient winter cooling. The importance of air flow driven heat transfer as a source of cooling is supported by the data. Results illustrate thermal heterogeneities within blocky layers and the importance of the seasonal snow cover pattern in addition to topography and microclimatic variability in high relief terrain is hypothesized.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"1 1","pages":"310 - 333"},"PeriodicalIF":1.5,"publicationDate":"2019-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83156836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-08-21DOI: 10.1080/04353676.2019.1644815
P. Wilson, H. Linge, J. Matthews, R. Mourne, J. Olsen
ABSTRACT Application of calibrated Schmidt-hammer surface-exposure dating (SHD) to the run-out debris of a rock avalanche at Alstadfjellet, Valldalen, southern Norway, has yielded ages that are consistent within uncertainties with terrestrial cosmogenic 10Be surface-exposure ages for the debris. SHD calibration was based on young and old control sites that were, respectively, recent road cuts / rockfall boulders of known age, and Younger Dryas moraines for which 10Be ages had been obtained. Three SHD calibration equations were generated based on different correction factors for the 10Be ages from the moraines. The SHD ages (10.3 ± 0.59–11.1 ± 0.64 ka) for the run-out debris are from 1.1 ka to 1.3 ka older than the corresponding 10Be ages (9.2 ± 0.7–9.8 ± 0.7 ka). In addition, the former ages have a precision of 1.18–1.28 ka (95% confidence intervals) as opposed to 2.8 ka (2σ range) for the latter ages. This work demonstrates that calibrated SHD can be of comparable accuracy to and may have improved precision over 10Be ages, and should be given greater consideration and prominence in Quaternary dating studies.
{"title":"Comparative numerical surface exposure-age dating (10Be and Schmidt hammer) of an early-Holocene rock avalanche at Alstadfjellet, Valldalen, southern Norway","authors":"P. Wilson, H. Linge, J. Matthews, R. Mourne, J. Olsen","doi":"10.1080/04353676.2019.1644815","DOIUrl":"https://doi.org/10.1080/04353676.2019.1644815","url":null,"abstract":"ABSTRACT Application of calibrated Schmidt-hammer surface-exposure dating (SHD) to the run-out debris of a rock avalanche at Alstadfjellet, Valldalen, southern Norway, has yielded ages that are consistent within uncertainties with terrestrial cosmogenic 10Be surface-exposure ages for the debris. SHD calibration was based on young and old control sites that were, respectively, recent road cuts / rockfall boulders of known age, and Younger Dryas moraines for which 10Be ages had been obtained. Three SHD calibration equations were generated based on different correction factors for the 10Be ages from the moraines. The SHD ages (10.3 ± 0.59–11.1 ± 0.64 ka) for the run-out debris are from 1.1 ka to 1.3 ka older than the corresponding 10Be ages (9.2 ± 0.7–9.8 ± 0.7 ka). In addition, the former ages have a precision of 1.18–1.28 ka (95% confidence intervals) as opposed to 2.8 ka (2σ range) for the latter ages. This work demonstrates that calibrated SHD can be of comparable accuracy to and may have improved precision over 10Be ages, and should be given greater consideration and prominence in Quaternary dating studies.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"40 1","pages":"293 - 309"},"PeriodicalIF":1.5,"publicationDate":"2019-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80538939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-03DOI: 10.1080/04353676.2019.1636545
M. Dąbski, B. Woronko, Patrycja Fabijańska, J. Otto
ABSTRACT Since the end of LIA climatic amelioration results in retreat of glaciers worldwide and the development of glacial forelands with freshly abraded rock surfaces undergoing weathering. When the timing of glacier retreat is known, glacier forelands are highly valuable study sites to investigate initial and short-term weathering processes. The aim of this study is to quantify limestone surface decay in the foreland of Hallstätter Glacier in Dachtein massif, Austria, based on the measurement of surface micro-roughness and weathering rind characteristics. By establishing a post-LIA chronosequence we seek to gain insight into initial stages of weathering in a cold alpine environment. Micro-roughness was measured with a use of Handysurf E-35B electronic profilometer, and weathering rind characteristics were determined based on SEM equipped with a microprobe. The micro-roughness increases from locations close to the glacier front towards the LIA moraine. The greatest measured increase occurs within the first 50 years since deglaciation. Weathering rinds are manifested as zones of micro-cracks and micro-pits, and accumulation of mineral grains at the rock surface and along the micro-voids. Increasing rounding of the grains and their development along micro-fissures is attributed to limestone dissolution, which is probably responsible for the development of micro-pits, best observed after c. 100 years since deglaciation. No protecting shield in a form of a weathering coating was observed. Instead, the weathering rind thinning is attributed to the weathering rind erosion. Results obtained provide further insight into initial stages of limestone weathering in a cold alpine environment.
{"title":"Micro-weathering of limestone surfaces in a foreland of Hallstätter Glacier (Dachstein, Austria)","authors":"M. Dąbski, B. Woronko, Patrycja Fabijańska, J. Otto","doi":"10.1080/04353676.2019.1636545","DOIUrl":"https://doi.org/10.1080/04353676.2019.1636545","url":null,"abstract":"ABSTRACT Since the end of LIA climatic amelioration results in retreat of glaciers worldwide and the development of glacial forelands with freshly abraded rock surfaces undergoing weathering. When the timing of glacier retreat is known, glacier forelands are highly valuable study sites to investigate initial and short-term weathering processes. The aim of this study is to quantify limestone surface decay in the foreland of Hallstätter Glacier in Dachtein massif, Austria, based on the measurement of surface micro-roughness and weathering rind characteristics. By establishing a post-LIA chronosequence we seek to gain insight into initial stages of weathering in a cold alpine environment. Micro-roughness was measured with a use of Handysurf E-35B electronic profilometer, and weathering rind characteristics were determined based on SEM equipped with a microprobe. The micro-roughness increases from locations close to the glacier front towards the LIA moraine. The greatest measured increase occurs within the first 50 years since deglaciation. Weathering rinds are manifested as zones of micro-cracks and micro-pits, and accumulation of mineral grains at the rock surface and along the micro-voids. Increasing rounding of the grains and their development along micro-fissures is attributed to limestone dissolution, which is probably responsible for the development of micro-pits, best observed after c. 100 years since deglaciation. No protecting shield in a form of a weathering coating was observed. Instead, the weathering rind thinning is attributed to the weathering rind erosion. Results obtained provide further insight into initial stages of limestone weathering in a cold alpine environment.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"28 1 1","pages":"277 - 292"},"PeriodicalIF":1.5,"publicationDate":"2019-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78153955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-03DOI: 10.1080/04353676.2019.1631608
D. Evans, M. Ewertowski, C. Orton
ABSTRACT A 1:14 500 scale glacial geomorphology and surficial geology map of the foreland of Hoffellsjökull, southeast Iceland is used to assess the glacial landsystem signature of the contrasting glacier-climate interactions of two separate flow lobes within one outlet glacier. This constitutes a valuable modern analogue for employing glacial geomorphological signatures as palaeoclimate indicators in ancient deglaciated terrains. The landsystem signatures of the glacier’s two flow lobes, Svínafellsjökull and Hoffellsjökull, are distinctly different. Svínafellsjökull displays inset and seasonally climatically-tuned push moraine sequences and subglacially streamlined surfaces typical of active temperate glaciers on sloping piedmont forelands. Hoffellsjökull displays the landform-sediment assemblages typical of outwash-head/depositional overdeepening scenarios, upon which closely-spaced composite push moraines reflect a long term quasi-stationary snout at and near the Little Ice Age maximum prior to 2000. Moraine spacing on the Svínafellsjökull foreland reflects an overall trend of annual recession punctuated by quasi-stability and/or readvance in the mid-1950s-1960 and 1975–2000 as recorded by two arcuate zones of closely-spaced and partially overprinted sawtooth and hairpin moraines. The pattern of moraine distribution here also reflects spatio-temporal changes in moraine-forming processes as dictated by changes in a combination of proglacial drainage characteristics and structural glaciology or crevasse architecture. The subglacial footprint of the Svínafellsjökull foreland contains features worthy of future research attention, including an arcuate zone of overridden moraines potentially indicative of a regional Holocene ice advance, prominent flutings and debris stripes potentially indicative of groove-ploughing and point-source bedrock plucking respectively, and relatively large drumlins.
{"title":"The glacial landsystem of Hoffellsjökull, SE Iceland: contrasting geomorphological signatures of active temperate glacier recession driven by ice lobe and bed morphology","authors":"D. Evans, M. Ewertowski, C. Orton","doi":"10.1080/04353676.2019.1631608","DOIUrl":"https://doi.org/10.1080/04353676.2019.1631608","url":null,"abstract":"ABSTRACT A 1:14 500 scale glacial geomorphology and surficial geology map of the foreland of Hoffellsjökull, southeast Iceland is used to assess the glacial landsystem signature of the contrasting glacier-climate interactions of two separate flow lobes within one outlet glacier. This constitutes a valuable modern analogue for employing glacial geomorphological signatures as palaeoclimate indicators in ancient deglaciated terrains. The landsystem signatures of the glacier’s two flow lobes, Svínafellsjökull and Hoffellsjökull, are distinctly different. Svínafellsjökull displays inset and seasonally climatically-tuned push moraine sequences and subglacially streamlined surfaces typical of active temperate glaciers on sloping piedmont forelands. Hoffellsjökull displays the landform-sediment assemblages typical of outwash-head/depositional overdeepening scenarios, upon which closely-spaced composite push moraines reflect a long term quasi-stationary snout at and near the Little Ice Age maximum prior to 2000. Moraine spacing on the Svínafellsjökull foreland reflects an overall trend of annual recession punctuated by quasi-stability and/or readvance in the mid-1950s-1960 and 1975–2000 as recorded by two arcuate zones of closely-spaced and partially overprinted sawtooth and hairpin moraines. The pattern of moraine distribution here also reflects spatio-temporal changes in moraine-forming processes as dictated by changes in a combination of proglacial drainage characteristics and structural glaciology or crevasse architecture. The subglacial footprint of the Svínafellsjökull foreland contains features worthy of future research attention, including an arcuate zone of overridden moraines potentially indicative of a regional Holocene ice advance, prominent flutings and debris stripes potentially indicative of groove-ploughing and point-source bedrock plucking respectively, and relatively large drumlins.","PeriodicalId":55112,"journal":{"name":"Geografiska Annaler Series A-Physical Geography","volume":"36 1","pages":"249 - 276"},"PeriodicalIF":1.5,"publicationDate":"2019-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85546533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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