Morphological and Morphometric Analyses of Drumlin Bedforms in the Omagh Basin, North Central Ireland

Morphological and morphometric analyses of diamict-dominated and rock-cored drumlins in the Omagh Basin, north central Ireland, identify five drumlin types (classical, shield, barchanoid, fused and superimposed) on the basis of outline morphology and topographic setting. Diamict drumlins are mainly of classical or fused type and are found in lowland and basinal locations. Rock-cored drumlins are more morphologically diverse and occur on high-level plateaus and upland flanks. Morphometric analysis reveals both spatial and statistically significant absolute differences between the elongation ratios and orientations of diamict and rock-cored drumlins. Equifinality of the drumlin form despite variable thicknesses of diamict (from a few metres to>30 m) suggests that substrate streamlining took place in several phases, including eroding bedrock into rock-cored drumlins prior to diamict deposition. This means drumlinization cannot be attributed to a single set of subglacial processes or a single time-interval.     

The geomorphic impact of glaciers as indicated by tors in North Sweden (Aurivaara, 68° N)

Geomorphological investigations carried out on 15 tor-like features located on the Aurivaara plateau (North Sweden, 68° N) provide new insights in the greatly debated age of these landforms. Erratics and till trapped deep in the tor joints support a pre-Weichselian age for tor formation. Moreover, the occurrence of various weathering stages in allochtonous material, the joint width up to 1.5 m (requiring long-term weathering), and the frequent association of tors with pediment-like forms, suggest pre-Quaternary tor formation. The juxtaposition of fresh erratics and in situ old weathering features (mushroom rocks, concentrically weathered well-rounded corestones, and grus) indicates a predominantly cold-based regime for the Scandinavian ice sheet, with erratics carried by the overlying moving ice being repeatedly deposited on tor summits during deglaciation phases. The relationships between tors and ice action indicated for the Aurivaara plateau result in the proposal of a morphodynamical succession of five tor subtypes ranging from the preservation of well-rounded corestones still embedded in grus (suggesting negligible glacial erosion) to the almost complete removal of tor features by ice scouring. A comparison with tors in similar geological and topographical contexts from the unglaciated Dartmoor area allows a tentative evaluation of an average overall glacial erosion of 0–10 m on the northern Sweden plateaus, in sharp contrast with the 190 m overdeepening of the nearby Torneträsk basin. Thus, this case study of Swedish tors provides additional support to the recent interpretations of relict landscapes in previously glaciated areas and is in accordance with the classical «model» of glacial selective erosion established in the Nordic and Arctic mountains.     

Luminescence Variations in Fast-Growing Stalagmites from Uppsala, Sweden

Two fast‐growing stalagmites from a cellar vault in Uppsala, southeast Sweden, are analysed for their luminescent properties. The results indicate that variations in luminescence intensity in the stalagmites are annual. Due to problems in finding a suitable absolute dating method this assumption cannot yet be firmly tested; however, results from radiocarbon dating of one of the stalagmites do not contradict the proposal that the laminae are annual. If so, the speleothems have been growing for 10–15 years with a growth rate of 3–8 mm per year, which is a similar rate to other fast‐growing speleothems in Great Britain that have formed from the reaction of lime mortar and carbon dioxide. It is likely that the assumed annual laminae of the luminescence record represent a flush of organic material.     

Recurring Jökulhlaups in Sälka, Northern Sweden

An ice‐dammed lake at the margin of the glacier Sälkaglaciären, in the Kebnekaise Mountains in northern Sweden, drained suddenly in July 2003 producing a flood with a measured peak discharge of 9.5±0.25 m³s^‐1. The total lake volume of 4.55×10⁵ million³ drained within two days. The hydrograph of this event is characteristic of a jökulhlaup controlled by a single basal ice tunnel that enlarges due to melting. The jökulhlaup had an exponential rise to a peak discharge, and following the peak, a very steep fall in discharge as the water supply to the drainage system ceased. A similar jökulhlaup was observed in August 1990 with an estimated release of 8.05×10⁵ m³ water. Jökulhlaups at Sälkaglaciären are recurring events and have been indirectly observed since the 1950s.     

Palsas in Härjedalen, Sweden: 1910 and 1998 Compared

In 1998 an area near Helagsfjället in Härjedalen was investigated in an attempt to relocate palsas discovered by the botanist Harry Smith in 1910. Several small palsa-like features with ice cores were detected. The palsas were found on an almost flat peat bog at 950 m, 3 km NW of Helagsfjället. Five clearly elevated mounds and some indistinct ones with palsa-like features were traced. The five mounds were about 0.6 m high and had an area of about 2 × 3 m. One of the mounds was examined in more detail. At a depth of 0.3 m in the peat an ice body with a hard ice core was found. This location is the most southerly area known with occurrence of palsa-like forms in Sweden at the present time. In spite of a warmer climate towards the latter part of this century, palsa-like features have survived in this area. The mean annual temperature barely fits the criterion for palsa formation while the mean annual precipitation is too high as compared with the general assumptions. The palsa formation is probably dependent on strong winds thinning out the snowcover.     

Segregation and Urban Unrest in Sweden

In 2009, Sweden experienced a wave of urban unrest concentrated in areas with large foreign-born populations. This episode was seen by many as reflecting a trend towards increased ethnically based residential segregation, in line with scholarly literatures that correlate inequality and rising segregation with increases in unrest or rebellion. In this paper, we analyze the empirical connection between ethnic residential segregation and episodes of urban unrest in Sweden. Unrest is measured by the number of car burnings reported to police between 2002 and 2009. We find a positive and statistically significant link between residential segregation and car burnings at the scale of municipalities and metropolitan districts. Unrest/rebellion is also correlated with high proportion of young adults and social welfare assistance.     

Lake Floor Morphology and Sediment Architecture of Lake Torneträsk,Northern Sweden

Here we present datasets from a hydroacoustic survey in July 2011 at Lake Torneträsk, northern Sweden. Our hydroacoustic data exhibit lake floor morphologies formed by glacial erosion and accumulation processes, insights into lacustrine sediment accumulation since the beginning of deglaciation, and information on seismic activity along the Pärvie Fault. Features of glacial scouring with a high‐energy relief, steep slopes, and relative reliefs of more than 50 m are observed in the large W‐basin. The remainder of the lacustrine subsurface appears to host a broad variety of well preserved formations from glacial accumulation related to the last retreat of the Fennoscandian ice sheet. Deposition of glaciolacustrine and lacustrine sediments is focused in areas situated in proximity to major inlets. Sediment accumulation in distal areas of the lake seldom exceeds 2 m or is not observable. We assume that lack of sediment deposition in the lake is a result of different factors, including low rates of erosion in the catchment, a previously high lake level leading to deposition of sediments in higher elevated paleodeltas, tributaries carrying low suspension loads as a result of sedimentation in upstream lakes, and an overall low productivity in the lake. A clear off‐shore trace of the Pärvie Fault could not be detected from our hydroacoustic data. However, an absence of sediment disturbance in close proximity to the presumed fault trace implies minimal seismic activity since deposition of the glaciolacustrine and lacustrine sediments.     

瑞典泥炭沼泽分布、利用与保护

瑞典是泥炭沼泽广布,泥炭沼泽学研究历史悠久的国家。基于实地考察、交流与文献整理,分析了瑞典泥炭沼泽分布与成因、泥炭沼泽研究、利用及保护状况。早期的瑞典沼泽学者在泥炭沼泽分类、演化及沼泽植物地理学研究等方面处于国际领先地位,对学科的发展做出了重大贡献。目前,瑞典在泥炭沼泽的利用与保护方面也走在世界的前列,特别是泥炭沼泽合理利用与保护及恢复并举,值得我国湿地管理部门借鉴。     

Ice-free conditions in Novaya Zemlya 35 000–30 000 cal years B.P., as indicated by radiocarbon ages and amino acid racemization evidence from marine molluscs

Novaya Zemlya was covered by the eastern part of the Barents–Kara ice sheet during the glacial maximum of marine isotope stage 2 (MIS 2). We obtained ¹⁴C ages on 37 samples of mollusc shells from various sites on the islands. Most samples yielded ages in the range of 48–26 ¹⁴C Ky. Such old samples are sensitive to contamination by young ¹⁴C, and therefore their reliability was assessed using replicate analyses and amino acid geochronology. The extent of aspartic acid racemization (Asp D/L) indicates that many of the ¹⁴C ages are correct, whereas some are minimum ages only. The results indicate that a substantial part of Novaya Zemlya was ice-free about 35–27 ¹⁴C Kya, and probably even earlier. Corresponding shorelines up to >140 m a.s.l. indicate a large Barents–Kara ice sheet during early MIS 3. These results are consistent with findings from Svalbard and northern Russia: in both places a large MIS 4/3 Barents–Kara ice sheet is postulated to have retreated about 50 Kya, followed by an ice-free interstadial that lasted until up to ca. 25 Kya. The duration of the MIS 2 glaciation in Novaya Zemlya was calculated by applying the D/L values to a kinetic equation for Asp racemization. This indicates that the islands were ice covered for less than 3000 years if the basal temperature was 0^oC, and for less than 10 000 years if it was −5^oC.     

南极冰盖地形数据库BEDMAP 2述评

南极冰盖物质收支与不稳定性对全球气候变化和海平面升高有着重要影响,而冰盖厚度和冰下地形则是研究南极冰盖的物质平衡、动力及不稳定性极为重要的参数。自20世纪50年代以来,国际上针对南极冰盖开展了大量的冰雷达以及重、磁测量,这些测量结果被汇集并形成冰厚和冰下地形数据库,进而服务于冰盖模式和地球系统研究,最新推出的成果便是BEDMAP 2(Bedrock Mapping Project 2)。首先介绍了BEDMAP 2的数据来源、结构以及数据处理,并讨论了数据的质量评价,然后分析了BEDMAP 2中展示的整个南极冰盖与冰下地形及其特点。最后,对于BEDMAP 2对中国在南极冰盖考察和研究方面的作用进行了一些讨论与展望。     

Variation of Stable Isotopes in Surface Snow along a Traverse from Coast to Plateau’s interior in East Antarctica and Its Climatic Significance

The variations of stable water isotopes of surface snow in east Antarctic Ice Sheet, are discussed by a total of 251 samples, which were taken along a 330 km traverse from Zhongshan Station to the outer edge of the Antarctic plateau and from four snow pits excavated along the route. Analyzing results of the samples showed the expected linear relationship between the parameters ?D and ?18O with slope S1 and intercept d1. When the data set was examined using a sliding window with a width of 5 samples, it was found that there were two areas with different ratios of S1 and d1. The boundary between these two areas occurred at an elevation of about 2,000 m, suggesting two different sources of water vapour. Nearly half (47%) of the fresh-snow samples had negative deuterium excess (d=?D? 8?18O) values, but few of the snow pit samples did, suggesting that variations of ? are quickly smoothed by isotopic diffusion in the near-surface firn. Analysis of the phase relationship between ?D and deuterium excess in the snow pit stratigraphies showed that they were mostly in phase from Jan. 1994 to Sept. 1995, but mostly out of phase from Sept. 1995 to Jan. 1997.     

Approval of Wolves in Scandinavia: A Comparison Between Norway and Sweden

Based on Norwegian and Swedish representative national samples, and samples from areas with large mammalian carnivores present, we investigated whether well-known predictors for approval of wolves may explain between-country differences. Swedes were in general more positive than Norwegians were, while respondents in large carnivore areas, regardless of nationality, were less positive. The profile of those who approved wolf presence was the same in all samples. The difference between the samples was greater in Sweden, indicating that the relationship between urbanized and rural areas is more polarized in Sweden compared to Norway. We suggest this to be an effect of the fact that Norway’s large carnivore and agriculture policies favor the rural population, and of a higher degree of urbanization in Sweden. We recommend future studies to look into the different power relations between people living in urban and rural areas, comparing countries with different degree of urbanization.     

Diatom-based water chemistry reconstructions from northern Sweden: a comparison of reconstruction techniques

The diatom composition in surface sediments from 119 northern Swedish lakes was studied to examine the relationship with lake-water pH, alkalinity, and colour. Diatom-based predictive models, using weighted-averaging (WA) regression and calibration, partial least squares (PLS) regression and calibration, and weighted-averaging partial least squares (WA-PLS) regression and calibration, were developed for inferences of water chemistry conditions. The non-linear response between the diatom assemblages and pH and alkalinity was best modelled by weighted-averaging methods. The lowest prediction error for pH was obtained using weighted averaging, with or without tolerance downweighting. For alkalinity there was still some information in the residual structure after extracting the first weighted-averaging component, which resulted in a slight improvement of predictions when using a two component WA-PLS model. The best colour predictions were obtained using a two component PLS model. Principal component analysis (PCA) of the prediction errors, with some characteristics of the training set included as passive variables, was performed to compare the results for the different alkalinity predictive models. The results indicate that calibration techniques utilizing more than one component (PLS and WA-PLS) can improve the predictions for lakes with diatom taxa that have broad tolerances. Furthermore, we show that WA-PLS performs best compared with the other techniques for those lakes that have a high relative abundance of the most dominant taxa and a corresponding low sample heterogeneity.     

Chironomids as quantitative indicators of mean July air temperature: validation by comparison with century-long meteorological records from northern Sweden

This study evaluates the potential of using chironomid assemblages to estimate past temperature changes by comparing chironomid-inferred temperatures to meteorological data for the last 87 years. This comparison is made using high-resolution (i.e., sub-decadally resolved) short cores of four lakes along a gradient of altitude (Lake Njulla, 999 m a.s.l., Lake 850, 850 m a.s.l., Lake Alanen Laanijavri, 365 m a.s.l. and Lake Vuoskkujavri, 348 m a.s.l.), vegetation (pine forest to alpine tundra vegetation) and temperature (mean July temperature of 12.4 to 8.1°C). Patterns of chironomid-inferred changes in mean July air temperature were highly comparable to changes in the meteorological data. Moreover, instrumental data were almost always within the specific errors of the quantitative estimates using chironomids. These results indicate that chironomids can be used as a powerful tool to reconstruct temperatures and that chironomids are sensitive enough to record temperature changes of low magnitude such as those recorded during the Holocene. Although this relationship between temperature and chironomid community is strong for the last 87 years, we cannot assume that other environmental factors such as organic matter, changes of lake water depth or oxygen availability were not more significant over longer temporal scales of the Holocene, or longer.     

Structure and contents of a new geomorphological GIS database linked to a geomorphological map — With an example from Liden, central Sweden

This paper presents the structure and contents of a standardised geomorphological GIS database that stores comprehensive scientific geomorphological data and constitutes the basis for processing and extracting spatial thematic data. The geodatabase contains spatial information on morphography/morphometry, hydrography, lithology, genesis, processes and age. A unique characteristic of the GIS geodatabase is that it is constructed in parallel with a new comprehensive geomorphological mapping system designed with GIS applications in mind. This close coupling enables easy digitalisation of the information from the geomorphological map into the GIS database for use in both scientific and practical applications. The selected platform, in which the geomorphological vector, raster and tabular data are stored, is the ESRI Personal geodatabase. Additional data such as an image of the original geomorphological map, DEMs or aerial orthographic images are also included in the database. The structure of the geomorphological database presented in this paper is exemplified for a study site around Liden, central Sweden.     

Rock Strength and Development of Glacial Valley Morphology in the Scottish Highlands and Northwest Iceland

Using data from the Scottish Highlands and northwest Iceland, the present study indicates that bedrock strength properties are an important control on the morphology of glacial valleys. Results indicate that on closely jointed metasedimentary bedrock of low rock mass strength, broad U‐shaped valleys are developed, whilst steeper sided, narrower cross‐profiles have been developed on igneous bedrock of high rock mass strength. Findings suggest it is the interplay of the mass strength of the subglacial bedrock and the dynamic properties of the eroding glacier that control valley morphological development. The implication is that realistic models of topographic development beneath ice sheets need to consider the rock mass strength properties of the eroded bedrock as well as the glaciological variables.