Changes in the Ice Boundary of the Vestfold Hills,East Antarctica, 1947 to 1990

The position of the ice boundary around the Vestfold Hills, East Antarctica (68°30'S, 78°00'E) was observed using a 43 year record of aerial photography from 1947 to 1990. The southern boundary, formed by Sørsdal Glacier, showed two main areas of ice retreat and no areas of advance. Stagnation and retreat of this boundary is interpreted to be contraction to former limits following the Chelnok Glaciation which occurred 7lt; 700 years BP. The eastern or continental ice sheet boundary showed five sites of rapid, localised incision and downwasting around supraglacial gullies. While no area of continental ice was noted to advance, continued accumulation and firnification of wind-drifted snow in the proglacial zone of the ice sheet in the southeastern corner of the hills may signify a locally positive ice mass balance. Until ice mass balance studies are carried out in the ablation zone surrounding the hills, evidence concerning whether the ice sheet boundary is retreating, stable or advancing will remain equivocal.     

Remarks on the Retreat of the North American Ice Sheet

A reply by two North American geographers to the preceding article presents some recent results of North American studies and suggests that the role of water bodies in influencing cyclogenesis is not universal. The Black Sea is cited as an example of a large water body that does not act as a major source of cyclonic activity. Other arguments are presented questioning the significance of the large proglacial lakes in influencing storm tracks near the margin of the ice sheet.     

Mountains

Glacier ice from the south and west invaded upper Strathspey forming an ice sheet not less than 700m thick as it submerged the entire landscape. When the ice sheet wasted away, its meltwaters created complex sequences of fluvioglacial landforms. During the final stages of deglaciation, deposits left by the wasting ice mass were eroded by water, terraces spread out, gorges cut and the broad, low‐lying corridor on both sides of the River Spey was formed. There is evidence of a later, local readvance of the glaciers in three of the tributary valleys.     

The last glaciers in part of the South East Grampians

In an area of 400 sq km in the south east Grampians including Glen Esk, Glen Clova and part of Glen Muick the limits of former corrie glaciers, valley glaciers and a plateau ice‐cap with associated outlet glaciers have been mapped. The limits of the former corrie and valley glaciers are often clearly defined by end moraines, boulder‐strewn ground, the down‐valley termination of hummocky moraines and/or the limits of meltwater channel systems, while in suitable locations outwash terraces usually occur. The glaciers are considered to have formed during the Loch Lomond (pollen zone III) Readvance, when new glaciers developed in upland sources following complete ice‐sheet decay. The readvance was accompanied in granite areas by the formation of large solifluction lobes, these lobes being found only outside the mapped ice limits. The interpretations presented are not in accord with those recently given by D. E. Sugden for the western Cairngorms.     

Reactive transport and thermo‐hydro‐mechanical coupling in deep sedimentary basins affected by glaciation cycles: model development,verification, and illustrative example

Deep sedimentary basins are complex systems that over long time scales may be affected by numerous interacting processes including groundwater flow, heat and mass transport, water–rock interactions, and mechanical loads induced by ice sheets. Understanding the interactions among these processes is important for the evaluation of the hydrodynamic and geochemical stability of geological CO₂ disposal sites and is equally relevant to the safety evaluation of deep geologic repositories for nuclear waste. We present a reactive transport formulation coupled to thermo‐hydrodynamic and simplified mechanical processes. The formulation determines solution density and ion activities for ionic strengths ranging from freshwater to dense brines based on solution composition and simultaneously accounts for the hydro‐mechanical effects caused by long‐term surface loading during a glaciation cycle. The formulation was implemented into the existing MIN3P reactive transport code (MIN3P‐THCm) and was used to illustrate the processes occurring in a two‐dimensional cross section of a sedimentary basin subjected to a simplified glaciation scenario consisting of a single cycle of ice‐sheet advance and retreat over a time period of 32 500 years. Although the sedimentary basin simulation is illustrative in nature, it captures the key geological features of deep Paleozoic sedimentary basins in North America, including interbedded sandstones, shales, evaporites, and carbonates in the presence of dense brines. Simulated fluid pressures are shown to increase in low hydraulic conductivity units during ice‐sheet advance due to hydro‐mechanical coupling. During the period of deglaciation, Darcy velocities increase in the shallow aquifers and to a lesser extent in deeper high‐hydraulic conductivity units (e.g., sandstones) as a result of the infiltration of glacial meltwater below the warm‐based ice sheet. Dedolomitization is predicted to be the most widespread geochemical process, focused near the freshwater/brine interface. For the illustrative sedimentary basin, the results suggest a high degree of hydrodynamic and geochemical stability.     

Glacial Stratigraphy of the Upper Mersey Valley,Tasmania

The upper Mersey Valley was glaciated on three occasions during the Pleistocene. The youngest, Rowallan Claciation, probably commenced after 28000 years B.P. The maximum ice limit was attained before 13500 years B.P., and retreat occurred before 10000years B.P. Deposits associated with Rowallan Glaciation are weakly weathered chemically. They overlie moderately weathered deposits that were formed during the Arm Glaciation, which is inferred from relative dating data to have occurred before the Last Interglacial Stage. North of the deposits and ice limits of the Arm Glaciation extremely weathered tills and rhythmites occur. They were formed by ice of the Croesus Glaciation which is inferred to be of Early Pleistocene age or older.     

Scottish landform examples 45: Sgriob na Caillich: a landslide-sourced medial moraine on the Isle of Jura

ABSTRACT

Medial moraines deposited by former glaciers and ice sheets are rare in Scotland. The most prominent example is the Sgriob na Caillich moraine, which consists of two to four parallel belts of angular quartzite boulders that extend northwestwards for over 3.5?km from the SW flank of Beinn an Oir on the Isle of Jura. The boulder belts extend to within 300?m of the present coastline, where they are truncated by a low bluff and raised marine terrace. The source of the moraine coincides with bedrock gullies and cliffs that represent the scars of former rock-slope failure(s), indicating that the moraine debris was sourced by one or more rockfalls or rockslides onto the ice surface after Beinn an Oir had emerged from the thinning ice cover as a nunatak. Exposure dating of boulders on the moraine indicate that it formed at 16.6?±?0.8?ka, consistent with the timing of ice-sheet retreat in this sector. The alignment of the moraine indicates ice-margin retreat to the SE; as regional ice-sheet retreat across the adjacent offshore shelf was to the NE, this anomaly implies that a residual icefield became stranded on Jura during ice-sheet retreat.     

A late Devensian Nunatak on the Knoydart peninsula,NW Scotland: Implications for ice‐sheet reconstruction

Geomorphological mapping and analysis of soil mineralogy indicates that all summits on the Knoydart Peninsula were over‐ridden by the last ice sheet apart from Ladhar Bheinn (1020 m), where the ice attained a maximum altitude of c. 950 m. This figure is consistent with evidence from adjacent areas and suggests that the last ice sheet descended westwards across Knoydart from c. 1000 m to c. 900 at the west coast, implying that most theoretically‐based ice‐sheet models are substantially in error in this area.     

Landscapes at the Periphery of Glacierization – Retrospect and Prospect

This paper reviews the evolution of palaeoglaciological reconstructions in regions at the periphery of glacierization, where an improved understanding of the role of glacial thermal regime has helped refine the delimitation of ice sheet maxima. Also significant has been the recognition in numerical models that some areas, especially ice sheet marginal zones, are subject to short periods of ice occupancy and hence that glacial landsystem signatures can be extremely subtle. This is compounded wherever cold-based conditions dominate during early stages of ice sheet recession, giving rise to a landform imprint typical of peripheral regions and hence often misinterpreted as unglaciated or glaciated only by older glaciations. Subtle landform imprints include meltwater channels, thin glacigenic veneers or scattered erratics and modified tors. More substantial glacigenic landform-sediment assemblages (‘drift belts’) do not always represent ice sheet maxima but instead may record significant changes in thermal regime, possibly linked to periods of ice-marginal stabilization. Some upland areas that lie beyond the traditionally demarcated limits of glaciation (e.g. Dartmoor in SW England) may contain subtle evidence of satellite ice cap development which has been overlooked due to the strong periglacial landform signature.     

LIVING MATTER AND TERRESTRIAL GLACIATION

Paleogeographic reconstructions and forecasts of climatic change have been based largely on the impact of cosmic and astronomic factors and have tended to ignore the impact of the geochemical activity of living organisms. Yet the CO₂ cycle in the biosphere (volcanic emissions on the income side and photosynthesis and burial of dead organic matter on the outgo side) can have a significant impact on climatic change because of the greenhouse effect. The CO₂ theory is used to explain the sequence of glacial and interglacial stages of the Pleistocene. Active volcanism during the Alpine mountain-building period resulted in a high CO₂ content in the atmosphere fostering the building up of a large phytomass. The continued absorption of CO₂ produced a cooling trend that led to the Ice Age. The spread of the ice sheet reduced the terrestrial biomass and thus the rate of CO₂ absorption, resulting in an increase of CO₂ in the atmosphere and a warming trend. In the interglacial stage that followed, the build-up of biomass again reduced atmospheric CO₂, producing a new cooling trend. This natural glacial-interglacial rhythm has been modified in the last 5,000 years by human activity. Maninduced reduction of phytomass (through deforestation) and, more recently, the intensive combustion of fossil fuels tend to increase the CO₂ content of the atmosphere (in contrast to the natural interglacial process) and make the advent of a new glacial stage unlikely. (The article was contributed by Victor L. Mote, University of Houston.)     

DAMMING JAMES BAY: I. POTENTIAL IMPACTS ON COASTAL CLIMATE AND THE WATER BALANCE

The proposed grand Canal project calls for the damming of James Bay and the diversion of its water southward. This first part of a two-part study models some potential impacts on the climate, water balance, and growth patterns in the James Bay coastal zone. Use is made of a linear relationship of Bowen ratio and temperature, developed from studies of coastal wetlands in southern and northwestern James Bay and central Hudson Bay. It is hypothesized that changing James Bay into a fresh-water lake and disrupting its coastal currents would result in a delayed Bay ice melt of unknown length in the spring. Allowing a delay to vary between 0 and 30 days results in the prediction of lesser evaporation and greater water surplus. These differences in magnitude increase with the length of delayed melt, but in all cases are most strongly evident during the peak of the growing season. Colder and wetter conditions would have a strong ecological impact on all coastal areas of western and southern James Bay. In the northwest this could change the species composition of coastal flora, cause forests to retreat from the coast, and result in the growth of permafrost there.     

PALEOGEOGRAPHY,TOPONYMY AND ETHNOGENESIS

An attempt is made by a Lithuanian physical geographer to combine the findings of paleogeography and place-name studies in shedding light on the time and place of the original settlement of the Indo-European peoples. The author also suggests that plausible elements in folk legend are susceptible to paleogeographic analysis, and he illustrates the point by relating Lithuanian folk legends about the origin of lakes to known thermokarstic processes giving rise to cave-in lakes. On the basis of a paleogeographic analysis of Lithuanian place names resembling the name Dunojus (Danube), the author suggests that the name of the Danube River is derived from an Indo-European root word such as duna, signifying an inlet or estuary of Late Pleistocene waterbodies with a sandy, dunelike shoreline. The vocabulary of Indo-European languages relating to features in the natural environment is used in establishing the time and location of the settlement of Indo-European peoples. On the basis of correspondences for tree names in the various Indo-European languages, the author concludes that the original Indo-European proto-ethnos sought refuge in the Pomeranian substage of the Late Pleistocene (about 20,000 years ago) in the mountain caves of central Europe. With the retreat of the ice sheet, the original Indo-Europeans began to migrate northward, and it was in the new areas of settlement in the plains of northern Europe that the Germanic, Slavic and Baltic branches of the Indo-Europeans were formed.     

Would North American Paleoindians have Noticed Younger Dryas Age Climate Changes?

Paleoindian groups occupied North America throughout the Younger Dryas Chronozone. It is often assumed that cooling temperatures during this interval, and the impact these would have had on biotic communities, posed significant adaptive challenges to those groups. That assessment of the nature, severity and abruptness of Younger Dryas changes is largely based on ice core records from the Greenland ice sheet where changes were indeed dramatic. This paper reviews climatic and environmental records from this time period in continental North America. We conclude that, on the Great Plains and in the Rocky Mountains, conditions were in reality less extreme. It therefore follows that conditions during the Younger Dryas interval may not have measurably added to the challenge routinely faced by Paleoindian groups who, during this interval, successfully (and perhaps rapidly) dispersed across the diverse habitats of Late Glacial North America.     

Some Thoughts on the Origin,Development and Retreat of Slopes

A senior Moscow University geomorphologist suggests that the limited Russian literature on slope development interprets “slope processes” too narrowly, restricting the term largely to mass wasting. Moreover, the convex-concave slope profile is viewed as the mature type under all climatic conditions. Such an approach tends to ignore the common phenomenon of slope retreat, which is presented as a more significant factor in slope development than the processes taking place on the slope itself. Several examples of slope retreat over long distances are given, suggesting that the profiles of retreating slopes depart from the convex-concave model. The author also takes issue with the view that stepped slope profiles tend to be smoothed by mass wasting. In his view, stepped profiles may in fact be further accentuated in slope development, for example, on valley sides made up of alternating soft and hard rock layers and in the case of so-called antiplanation terraces in high-latitude mountains. The author also takes issue with the view that “cattle tracks” are primary slope forms. He suggests they are secondary formations superimposed on ridges and other microrelief forms produced by mass wasting on the slope.     

Practical surveying in schools

Analysis of detailed geomorphological mapping enables a sequence of glacial events to be established. An ice sheet whose source was to the west of the area of study is shown, by the suites of fluvioglacial landforms produced, to have down‐wasted in situ; meltwaters escaped beneath or through the ice, moving uphill across certain areas. Finally, a sub‐aerial drainage system was established and outwash terraces were spread down valley.     

Terrace Dissent in Urban Western Sahara: Between Plazas and Homes

Since 2018, domestic Saharawi houses in occupied Western Sahara have become tactical sites for organising dissent. The move to interior spaces came as a collective retreat from the city's public plazas. This retreat from extravagant plazas illustrates that the turn toward interior spaces was a tactic in front of destructive occupation power rather than a withdrawal. This article explores Saharawi spatial production of dissent under two different political moments. I ask, what spaces of dissent do people under occupation animate when the city is mobilised against them? This paper is based on ethnographic engagement with encounters between Saharawis and Moroccan security forces that led Saharawis to construct the house as its own public. I demonstrate interiorising the exterior by analysing homes’ terraces as the new space of urban dissent in the Western Sahara. As such, the terrace appears as a new space and a new tool of and in urban insurgency.     

Securing Landscape Resilience to Tropical Cyclones in Australia's Wet Tropics under a Changing Climate: Lessons from Cyclones Larry (and Yasi)

Tropical cyclones are part of the ecosystem dynamics of rainforests in the Wet Tropics of Australia, and intact forest areas show remarkable ability to recover from cyclonic disturbance. However, forest remnants, littoral rainforests, and riparian vegetation have been shown to be particularly susceptible to cyclonic winds and post‐disturbance weed invasion with consequences for their long‐term conservation values. I evaluate the frequency and intensity of tropical cyclones impacting the Wet Tropics region since records began in 1858. The recent Category 4 cyclones featured in this study, Larry and Yasi, had return intervals of about one in 70 years. I then discuss the natural resource management (NRM) lessons from Cyclone Larry and put forward practical recommendations on how authorities should deal with natural resources in the clean‐up and recovery phases. I argue that natural resources must be treated as valuable commodities by including their protection and rehabilitation in the same way that human livelihoods, infrastructure and industry are covered in disaster management planning. This requires NRM issues to be included in disaster response policy and legislation, together with ensuring that structures are in place to mitigate the effects of cyclones on natural resources. There is a general consensus that tropical cyclone intensity will increase under climate change while frequency will decrease slightly. This has profound implications for the long‐term sustainability of ecosystems in the Wet Tropics. There is a real risk of a phase shift to vegetation types dominated by disturbance species, including weeds, at the expense of cyclone intolerant species. It is therefore important that we begin to build more cyclone resilient landscapes to reduce the vulnerability of our remaining rainforest habitats and primary production systems. Securing landscape resilience requires greater NRM investment in key areas, including landscape connectivity, river repair, protecting coastal assets and cyclone resilient farms. While climate change poses a long‐term threat to the rainforests of the region, we need to focus on more immediate pressures affecting our remaining biodiversity, notably clearing of native habitat, habitat fragmentation and degradation, and biosecurity issues.     

哈尔滨市创建世界冰雪旅游名城对策研究

建设世界冰雪旅游名城已成为新世纪初哈尔滨市实现跨越式发展的一项重要战略举措,如何发展冰雪旅游,做好冰雪旅游产业文章,真正将哈尔滨建设成为国际知名的冰雪旅游城市,是哈尔滨面临的重大课题。本文提出按国际水准进行规划、构建“政府主导社会参与市场运作”发展格局、走“提质增效”的经营道路、推进产品创新、制定有效的市场营销策略、营造世界冰雪旅游名城环境氛围、提升旅游服务、重视人才培养实施人才兴旅战略等相应对策。     

THE TRAVERSETTE (ITALIA) ROCKFALL: GEOMORPHOLOGICAL INDICATOR OF THE HANNIBALIC INVASION ROUTE*

Numerous small, low volume rockfalls around the crest of the Italian and French Alps, principally formed from calcareous mica schist and metabasalt, have impeded travel across the major cols for millennia. As documented by Polybius and Livy in the ancient literature, Hannibal's Army was blocked by a two-tier rockfall on the lee side of the Alps, a rubble sheet of considerable volume that delayed his exit into the upper Po River Country. An in-depth study of the possible cols reveals that the only such two-tier landform lies below the Col de la Traversette, at ∼2600 m above sea level. In addition, it represents a problem in applied geomorphology, namely, to accurately determine the nature of the surface rubble sheet in Hannibal's time (218 bc ). A reconstruction of the initial deposit, likely Late Glacial, following the retreat of the Po Glacier, is based upon an analysis of the source rock and geological setting. Further specifications on the geometry of the Neoglacial cover sediment are based on weathering characteristics, lichen cover and soil development. The 'myth' that Hannibal fired the rockfall to comminute boulders is plausible given the vegetation records which support tree growth nearby, but is unsubstantiated by the lack of any carbonized rock.     

商鞅法哲学研究

法家学派在时间上有前期、后期之分,在地域上有齐法家和三晋法家之分。商鞅是前期法家名代表人物,其法学理论典型地体现于社会终极理想之中。他认为人类社会的历史可以划分为两大阶段：首先是法治化社会,以法治国,在社会高度法治化基础之上,人类有望进入其理想化阶段——道德自律社会。法的力量由中心退居边缘,伦理道德价值体系开始由边缘走向中心,道德价值体系成为人类社会最高原则。从“法治”到“德治”,这是商鞅法学理论的逻辑过程,也是商鞅法学理论的全部内涵。