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After the Elatina glaciation of Snowball Earth, at least four distinct glacial advances and sea-level retreats punctuated Ediacaran time: Gaskiers glaciation (580 Ma), Fauquier glaciation (571 Ma), Bou-Azzer glaciation (566 Ma) and Hankalchough glaciation (551 Ma). Tillites or diamictites are commonly controversial, but periglacial paleosols with distinctive physical structure and degree of chemical weathering offer supporting evidence of glaciation and sea-level change useful for stratigraphic correlation. This paper reviews glacial advances of the Ediacaran stratotype and other sequences, and also reveals the value of paleosols and chemical index of alteration to understand the upper Squantum and Brookline members of the Roxbury Conglomerate near Boston, Massachusetts. The Boston Bay ice wedges are periglacial paleosols, and evidence of maritime glacial climate like that of modern coastal Greenland and Arctic Canada. Simple discoidal vendobiont fossils (Aspidella terranovica) in the Dorchester Member of the Roxbury Conglomerate and in the Cambridge Argillite are in heterolithic shale–siltstone facies that are interpreted as intertidal to shallow marine environments. Local marine transgressions and other paleosols showing significant chemical weathering represent temperate interglacial paleoclimates. Short glacial advances affecting climate and sea-level enable subdivision of the Ediacaran Period. Four distinct glacial advances and sea-level retreats punctuated Ediacaran time: Gaskiers (580 Ma), Fauquier (571 Ma), Bou-Azzer (566 Ma), Hankalchough (551 Ma). Paleosols with distinctive structures such as ice wedges were periglacial. Squantum Member diamictites near Boston, Massachusetts are Gaskiers age. [ABSTRACT FROM AUTHOR]

Earth has experienced several phases of glacial and interglacial climates over the past 200,000 years. A majority of that time has been under colder than current conditions. During these periods, large amounts of water were frozen at the poles, which lowered sea-levels by as much as 130 m. The climate has been so weighted toward colder conditions, that 90% of human history has taken place during lower than modern sea-levels. The reintroduction of freshwater into the oceans after the last glacial maximum radically changed global sea-levels, inland water tables, and littoral landscapes. Over the last 20,000 years, approximately 20 million km2 of coastal landscape has been submerged worldwide, an area roughly the size of South America. The inundation of these landscapes has created gaps in our understanding of the history of humans directly interacting with the coasts. Here, I briefly review key global Middle and Upper Pleistocene era (162,000–11,500 years ago) archaeological sites and present a model for eastern coastally-adapted Paleoindian sites on the North American Atlantic and Gulf of Mexico (GOM) submerged continental shelf. It is clear from this review that coastally-adapted Paleoindian sites will not likely reflect the quintessential hallmarks of upland Paleoindian sites, with carefully-crafted bifacial projectile points constructed from exotic lithic material, megafaunal remains, ephemeral campsites signifying high mobility. Instead, coastal Paleoindian sites will likely contain micro-blade and utilized flakes technology constructed from locally sourced lithic material in place of projectile points, with few terrestrial fauna, replaced by shellfish middens at longer-term residential sites, within 10 to 12 km of the coast. [ABSTRACT FROM AUTHOR]

Recently acquired seismic data in the eastern portion of the Amadeus Basin of central Australia have enabled disconformities at the base of both the Sturt and Elatina glaciogenic sequences within the Neoproterozoic succession to be mapped on a semi-regional scale. On a more detailed scale, along the shallowly shelving eastern flank of the basin, seismic data have revealed features that demarcate the transition from a grounded to floating, or possible absent, Sturt ice-sheet. Coincident with this transition is an extensive mound-like accumulation of glacial debris, some 10 to 15km wide, 300 m high and extending at least 150km subparallel to the northeast-southwest-oriented basin margin. This glacial debris entered the basin subglacially through meandering tunnel valleys, one of which can be mapped seismically. [ABSTRACT FROM AUTHOR]

Paleoamerican colonization models have emphasized the importance of coastal zones for provisioning hunter gatherers with a diverse range of subsistence resources. This article expands on recent research by Lowery et al. 2012, and presents a model to explain the distribution of Clovis points across the Atlantic slope of Eastern North America. Marine transgression since the last glaciation has submerged large tracts of the Atlantic continental shelf. Global bathymetric data was used to estimate the Clovis age shoreline from Delaware to Florida. Clovis biface data for modern coastal areas, obtained from the Paleoindian database of the Americas, was compared to the slope of the paleo-shoreline to predict coastal zone preference. Results indicate a relationship between point distribution and coastal zone type. Areas where major rivers with high-quality tool-stone intersect broad coastal zones served important roles to Clovis subsistence adaptations. The potential exists for early Paleoamerican sites along the continental shelf submerged beneath 55–75 m of the Atlantic Ocean. Modern coastal regions with high densities of Clovis points may serve as analogues for identifying earlier sites that have been submerged as a result of marine transgression. [ABSTRACT FROM PUBLISHER]

The INTIMATE (Integration of ice-core, marine and terrestrial records) project, the successor to the North Atlantic Seaboard Programme of International Geological Correlation Programme (IGCP-253) ‘Termination of the Pleistocene’, began in 1995 with the aim of integrating proxy climate records from around the North Atlantic during the Last Termination (18–8 ka BP). The INTIMATE remit has since expanded geographically to include the entire Atlantic basin and Australasia, while an extended temporal framework now covers the early Holocene and the Last Glacial cycle. This short paper outlines the principal achievements of the INTIMATE research community, which include the development of an event stratigraphy for the North Atlantic region; the establishment of protocols for ice–land–ocean correlation; important contributions to geochronology, most notably to tephrochronology, and to palaeoenvironmental and palaeoclimatic reconstructions; and the designation of the Greenland ice-core record as the global stratotype for the Pleistocene–Holocene boundary. Future directions of the INTIMATE programme are also briefly considered. [ABSTRACT FROM AUTHOR]

Trimlines mark the boundary between glacially eroded landscapes on low ground and landscapes dominated by evidence of periglacial weathering on higher summits. For many years the trimlines of Scandinavia, Britain and Ireland have been interpreted as marking the surface of the ice sheets at the maximum of the last glaciation, but recent cosmogenic exposure dating of erratics far above the trimlines in NW Scotland shows this to be false. The trimlines in that area must represent an englacial thermal boundary between warm (eroding) ice and cold (protecting) ice. It is now clear that even very experienced geomorphologists cannot necessarily tell the difference between terrain that has been recently glaciated and terrain that has not, because cold-based ice can leave virtually no trace. This calls into question not only the interpretation of high-level trimlines elsewhere, but also the mapping of the lateral limits of past glaciations, which are often based on similar or even weaker geomorphological and sedimentological evidence. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

After catastrophic disturbances, depleted substrates are readily colonised by organisms that capture nitrogen from the atmosphere and extract phosphorus from minerals. Our main objective was to compare the pattern of ecosystem development following deglaciation in Chile and New Zealand. Results show a similar pattern of C and N accumulation and decline in soil chronosequences, similar decline in biological nitrogen fixation (BNF) and similar δ15N-enriched signal at later stages, providing evidence for the existence of progressive, maximal and retrogressive phases of ecosystem development. However, contrasting patterns between Chilean and New Zealand sites are evident during the progressive phase, when higher C/N, C/P and N/P ratios are found in soils and leaves in Chile than in New Zealand, suggesting a higher nutrient limitation and nutrient use efficiency in the former. Highest rates of BNF were found at the early stages of both the Chilean and New Zealand chronosequences. Contrasting patterns across regions were the lack of a decline in soil total P, and the depleted values in soils of15N during the progressive phase in the Chilean chronosequences, but enriched values, suggesting an open nitrogen cycle, during retrogression in both the Chilean and the New Zealand chronosequences. Overall, these results provide evidence for the existence of retrogression with ecosystem development in the sub-Antarctic region of the world, even when comparing contrasting biomes, climatic regions and geological substrates. [ABSTRACT FROM AUTHOR]

Globally, glacial and paraglacial environments in mountains are vulnerable to the effects of ongoing contemporary climate change (global warming), but monitoring of such systems today provides only a limited spatial and temporal viewpoint of their likely evolution over coming decades to centuries. This is because these environments show complex and nonlinear responses to forcing and are affected by time lags, feedbacks and antecedent factors, including geologic control and geologic history that present monitoring of these systems cannot capture. In order to evaluate how glacial and paraglacial environments in mountains are likely to respond to future climate change, we consider how these environments have responded to climate change in the past (the last glacial-interglacial transition, and the Little Ice Age). From this, we may anticipate the likely responses of glacial and paraglacial environments in mountains to global warming over coming decades. We show that future changes in glacial and paraglacial environments, in particular in glaciated regions in continental interiors, have downstream implications for the biosphere (including biodiversity and ecosystem services, sustainable agriculture and water resources), the human environment (including cultural and heritage landscapes and social/economic activities), and for policy and planning. These will be important issues for the later twenty-first century and beyond. [ABSTRACT FROM AUTHOR]

The Wet Cave vertebrate fossil deposit of the Naracoorte Caves in south-eastern South Australia contains a rich and diverse assemblage of small mammal fauna known to span the Upper Pleistocene–Holocene. Here, we describe five previously unidentifiedin situunits (A, B, C, E and F) and one likely reworked unit (D) in the Wet Cave sedimentary profile, which are correlated with paleoclimatic conditions associated with the Last Glacial Cycle. Additional radiocarbon dates presented here provide a finer temporal resolution for the upper sections of the sequence than previously available and reveal rapid deposition of polished quartz sands laminated with brown silts during the last glacial maximum (LGM). Change in sediment type and depositional processes are dated from 16.8 to 16.4 k cal y BP and are associated with the onset of deglaciation. The characteristics of the fivein situdepositional units are similar to those identified from the contemporaneous fossil and sedimentary sequence of Blanche Cave 3rd Chamber, located approximately 400 m away, reflecting interactions between paleoclimate, sediment mobility and deposition at this locality. Greater variation is evident between the Wet Cave sedimentary profile and the inner chamber of Robertson Cave, located approximately 6 km away and shows that local processes and cave structure exerted some control on sediment accumulation. Paleoclimatic inferences from the depositional sequence of Wet Cave are broadly consistent with those inferred from regional landforms for south-eastern Australia but provide a local signal more suitable for cross-correlation of the fossil faunas. In particular, the Wet Cave sequence suggests that local conditions were relatively stable in the lead up to the LGM despite fluctuation in both local and regional effective precipitation. Sedimentary units associated with the post-LGM deglaciation are characterised by alternating sand and sandy-silt layers, assumed to reflect the impact of enhanced seasonality and/or climatic fluctuation leading towards the Holocene. [ABSTRACT FROM AUTHOR]

We present a glacial geomorphological map covering 1.04 × 105 km2 of the Shaluli Shan (Shan = Mountain), southeastern Tibetan Plateau. Using a 90 m digital elevation model from the Shuttle Radar Topography Mission and 15/30 m Landsat Enhanced Thematic Mapper Plus satellite imagery, we have mapped glacial valleys, marginal moraines, hummocky terrain, glacial lineations and ice-scoured terrain. Lineations and scoured areas largely overlap on the low relief granite plateau of the Shaluli Shan and relate to former ice cap glaciation. These landscape features indicate that past ice cap glaciation included basal sliding conditions, and thus warm-based ice. Glacial valleys and marginal moraines are dominant landforms in the high mountain ranges of Shaluli Shan and occur on and fringing the plateau. This glacial geomorphological map forms the basis for paleoglaciological reconstructions of this southeastern Tibetan Plateau region and indicates the former presence of multiple glaciations involving valley glaciers and ice caps. The map is presented at a scale of 1:630,000. [ABSTRACT FROM AUTHOR]

ABSTRACT Annual air-sea exchange of CO2 in Young Sound, NE Greenland was estimated using pCO2 surface-water measurements during summer (2006-2009) and during an ice-covered winter 2008. All surface pCO2 values were below atmospheric levels indicating an uptake of atmospheric CO2. During sea ice formation, dissolved inorganic carbon (DIC) content is reduced causing sea ice to be under saturated in CO2. Approximately 1% of the DIC forced out of growing sea ice was released into the atmosphere while the remaining 99% was exported to the underlying water column. Sea ice covered the fjord 9 months a year and thereby efficiently blocked air-sea CO2 exchange. During sea ice melt, dissolution of CaCO3 combined with primary production and strong stratification of the water column acted to lower surface-water pCO2 levels in the fjord. Also, a large input of glacial melt water containing geochemically reactive carbonate minerals may contribute to the low surface-water pCO2 levels. The average annual uptake of atmospheric CO2 was estimated at 2.7 mol CO2 m−2 yr−1 or 32 g C m−2 yr−1 for the study area, which is lower than estimates from the Greenland Sea. Variability in duration of sea ice cover caused significant year-to-year variation in annual gas exchange. [ABSTRACT FROM AUTHOR]

Lilleøren, K.S. and Etzelmüller, B., 2011.Aregional inventory of rock glaciers and ice-cored moraines in Norway. Geografiska Annaler: Series A, Physical Geography, 93, 175-191. DOI: 10.1111/j.1468-0459.2011.00430.x ABSTRACT Landforms in Norway indicating present and former permafrost have been compiled in order to discuss Holocene landform development patterns. In total 307 permafrost landforms have been mapped, consisting of rock glaciers and ice-cored moraines. The landforms were classified as active/inactive (intact) or relict landforms, and by origin. In northern Norway, permafrost landforms exist down to sea level and the majority of the landforms are relict talus-derived rock glaciers. In southern Norway, permafrost landforms are restricted to high elevations and the majority of the landforms are connected to glacial activity and classified as active. In the present paper, this contrasting pattern is interpreted to reflect that different processes leading to a permafrost landform also represent different ages and climatic regimes during their formation. The inventoried landforms reproduce the modelled permafrost distribution for Norway satisfactorily. [ABSTRACT FROM AUTHOR]

A fully coupled atmosphere-ocean general circulation model is used to simulate climate conditions during the last glacial maximum (LGM). Forcing conditions include astronomical parameters, greenhouse gases, ice sheets and vegetation. A 50-yr period of the global simulation is dynamically downscaled to 50 km horizontal resolution over Europe with a regional climate model (RCM). A dynamic vegetation model is used to produce vegetation that is consistent with the climate simulated by the RCM. This vegetation is used in a final simulation with the RCM. The resulting climate is 5-10 °C colder than the recent past climate (representative of year 1990) over ice-free parts of Europe as an annual average; over the ice-sheet up to 40 °C colder in winter. The average model-proxy error is about the same for summer and winter, for pollen-based proxies. The RCM results are within (outside) the uncertainty limits for winter (summer). Sensitivity studies performed with the RCM indicate that the simulated climate is sensitive to changes in vegetation, whereas the location of the ice sheet only affects the climate around the ice sheet. The RCM-simulated interannual variability in near surface temperature is significantly larger at LGM than in the recent past climate. [ABSTRACT FROM AUTHOR]

The interglacial-glacial decrease in atmospheric methane concentration is often attributed to a strong decline in the wetland source. This seems consistent with the extreme coldness and vastly expanded ice sheets. Here we analyse coupled model simulations for the last glacial maximum from the Paleoclimate Modelling Intercomparison Project, using simple relations to estimate wetland characteristics from the simulated climate and vegetation. It is found that boreal wetlands shift southward in all simulations, which is instrumental in maintaining the boreal wetland source at a significant level. The mean emission temperature over boreal wetlands drops by only a few degrees, despite the strong overall cooling. The temperature effect on the glacial decline in the methane flux is therefore moderate, while reduced plant productivity contributes equally to the total reduction. Moisture effects play a role on the local scale only, while averaging out globally. [ABSTRACT FROM AUTHOR]

Based on information from ITS (112 specimens) and the chloroplast markers trnL-trnF and rpl16 (116), this study reconstructs the phylogeography of the moss Sanionia uncinata, with a focus on Europe. In a global context, especially ITS data, suggest a scenario with a major split, between one southern hemisphere and one eastern Asiatic lineage. Descendants of the first dispersed back to the northern hemisphere where they are presently widespread, and those of the second lineage likewise spread over much of the north. Within the latter, a separate group evolved which is the only one present in central Europe and has not reached arctic Europe. Members of this group also colonized tropical Africa. In addition, members of the two main lineages most likely survived the last glaciation in the north or north-east, whereas representatives of the last evolved group could have survived the glacial period in southern Europe. The results underline potential problems with too small data sets in phylogeographic studies. European ITS data suggest two cryptic species, but the global sampling includes representatives of several of the haplotypes that are 'missing' in Europe, and the chloroplast data suggest partly different groups than ITS. [ABSTRACT FROM AUTHOR]

Despite over a century of research, reconstructions of the western margin of the last British-Irish Ice Sheet remain controversial. This is mainly because the ice sheet extended offshore onto the continental shelf and therefore significant portions of the glacial record are below present sea level. The availability of high resolution multibeam swath bathymetric and geophysical sub-bottom data for over ~30,000 km2 of the northwest Irish continental margin (between 55°40′ and 54°18′ N, and 7°50′ and 11°4′ W) has made it possible to map glacial features on the continental shelf and glacially-related features on the continental slope and rise. The resulting map, presented here at a scale of 1:260,000, shows that the major glacial features consist of subglacial bedforms and nested arcuate moraines of different orientations across the width of the shelf. Distal to these moraines, the outermost shelf and upper slope are crossed by subparallel and cross-cutting furrows created by iceberg scouring and meltwater discharge at the ice margin. A well-developed system of gullies and canyons and frequent escarpments incise the continental slope. Several large depositional lobes, likely related to the delivery of vast amount of sediment at the ice margin are found in inter-canyon areas and at the base of the slope. Collectively these data show an extensive ice sheet margin across the entire shelf and sedimentation on the continental margin was greatly affected by the presence of the ice margin at the shelf edge. [ABSTRACT FROM AUTHOR]

Here we present a series of six maps illustrating the distribution of end moraines in Far NE Russia. The maps are the first to systematically document the distribution of moraines across this region from the Verkhoyansk Mountains at the westernmost limit of our study area to the Chukchi Peninsula in the NE and to Kamchatka in the south, covering almost 4 million km2. Moraines were identified and mapped from analysis of satellite images and digital elevation model data. A total of 2173 moraines are identified, and we highlight some 197 more speculative features (perhaps moraines) that require further investigation. The distribution of moraines indicates that much of the region, now largely ice-free, was formerly occupied by glaciers centred upon the region's uplands and that glacier outlets were typically < 200 km in length. The maps demonstrate the usefulness of remote sensing to derive an improved understanding of the glacial history of this vast and isolated region, and we present them to stimulate further work and act as a systematic framework for targeted geochronometric dating. [ABSTRACT FROM AUTHOR]

A semi-empirical model has been developed to reproduce glacial–interglacial changes of continental dust and marine sodium concentrations (factor of ∼50 and ∼5, respectively) observed in inland Antarctic ice cores. The model uses conceptual pathways of aerosols within the high troposphere; assumes the dry deposition of impurities on the Antarctic surface; uses estimates of aerosol transit times taken independent of climate; assumes a temperature-dependent removal process during aerosol pathways from the mid-latitudes. The model is fitted to the data over the last four climate cycles from Vostok and EPICA Dome C Antarctic sites. As temperature is cooling, the aerosol response suggests different modes of climate couplings between latitudes, which can be continuous or below temperature thresholds for sodium and dust, respectively. The model estimates a southern South America dust source activity two to three times higher for glacial periods than for the Holocene and a glacial temperature over the Southern Ocean 3–5 °C cooler. Both estimates appear consistent with independent observations. After removal of temperature effects, dust and sodium residuals for both sites show orbital frequencies in opposite phase at the precession timescale. Such long-term insolation-related modulation of terrestrial and marine aerosol input, could provide a chemical pacemaker useful for refining ice core chronologies. [ABSTRACT FROM AUTHOR]

The climate has changed through the history of the Earth as evidenced in the geological records. Today we might be experiencing a climate change of the same magnitude as the transition into an ice age caused by very rapid burning and emission to the atmosphere of a substantial part of the fossilised carbon. Whether this leads to a gradual warming or if we will experience a transition into a different climatic state is presently unknown. The present day state-of-the-art numerical climate models are capable of producing fair representations of the current climate and are as such trusted to also predict the climate changes due to increasing atmospheric concentrations of greenhouse gases. However, the models are not presently capable of reproducing the rapid transitions from one climatic state, such as a glacial climate, into another, such as the present climate. The reason for this is unknown. The transitions are inherently 'non-linear' and thus not accessible through linear response theory. The term 'non-linear' is in this context defined as the phenomenon that the response of the system to a change in the forcing of the system is not linearly proportional to the forcing. This would happen if a threshold is reached such that the state of the system becomes unstable and the system bifurcates into a different state. There are strong indications in the geological records of this kind of behaviour for the climate. These dynamics can be understood in the context of fairly simple models of the climate. [ABSTRACT FROM AUTHOR]

Polar regions are very sensitive to climate variability. Glacial environments, such as Spitsbergen, respond drastically to climate warming by the disintegration of ice masses, release of huge amounts of free water and rapid evolution of terrestrial landforms. Paraglacial studies have shown that sediment yield decreases with time following a relaxation curve. The study examines the effects of scaling on rhythms of deglaciation and sediment fluxes in a small catchment. It appears that the paraglacial sequence, known as a morphogenic crisis, could be affected by internal small threshold events which are able to mobilize large quantities of sediment. It means that, at small scale, the curve profile is more irregular than suggested by large-scale models. [ABSTRACT FROM AUTHOR]

The late Early Permian (273 - 271 Ma) Wandrawandian Siltstone in the southern Sydney Basin of New South Wales represents a marine highstand that can be correlated over 2000 km. A mainly fine-grained terrigenous clastic succession, the Wandrawandian Siltstone contains evidence for cold, possibly glacial conditions based on the presence of outsized clasts and glendonites, mineral pseudomorphs after ikaite, a mineral that forms in cold (0 - 7°C) marine sediments. A lithostratigraphic and facies analysis of the unit was conducted, based on extensive coastal outcrops and continuous drillcores. Eight facies associations were identified: (i) siltstone; (ii) siltstone with minor interbedded sandstone; (iii) interbedded tabular sandstone and siltstone; (iv) admixed sandstone and siltstone to medium-grained sandstone; (v) discrete, discontinuous sandstone intervals; (vi) chaotic conglomerate and sandstone in large channel forms; (vii) chaotically bedded and pervasively soft-sediment-deformed intervals; and (viii) tuffaceous siltstone and claystone. Using lithology and ichnology, relative water depths were ascribed to each facies association. Based on these associations, the unit was divided into five informal members that reveal a history of significant relative sea-level fluctuations throughout the formation: member I, interbedded/admixed sandstone and siltstone; member II, siltstone; member III, slumped masses of members I and II; member IV, siltstone and erosionally based lensoid sandstone beds and channel bodies; and member V, interbedded/admixed sandstone and siltstone with abundant tuffs. Member I marks an initial marine transgression from shoreface to offshore depths. Member II records the maximum water depth of the shelf. Member III is interpreted to be a slump sheet; plausible mechanisms for its emplacement include seismicity produced by tectonism or glacio-isostatic rebound, changes in pore-water pressures due to sea-level fluctuations, or an increase in sedimentation rates. Members IV and V record minor fluctuations in depositional environments from offshore to shoreface water depths. Member IV includes regionally extensive, large channel bodies, with composite fills that are interpreted as storm-influenced mass-flow deposits. Member V includes a greater abundance of volcanic ash. Glacial controls (isostasy, eustasy) and tectonic affects may have worked in concert to produce the changes in depositional environments observed in the Wandrawandian Siltstone. [ABSTRACT FROM AUTHOR]

Carbon sequestering in peatlands is believed to be a major climate-regulating mechanism throughout the late Phanerozoic. Since plant life first evolved on land, peatlands have been significant carbon sinks, which could explain significant parts of the large variations in atmospheric carbon dioxide observed in various records. The result is peat in different degrees of metamorphosis, i.e. lignite, hard coal and graphite. During phases of extensive glaciations such as the 330–240 Ma Pangea Ice Age, atmospheric carbon dioxide was critically low. This pattern repeats itself during the Pleistocene when carbon dioxide oscillates with an amplitude of c. 200–300 ppmv. This paper suggests that the ice age cycles during the Pleistocene are generated by the interglacial growth of peatlands and the subsequent sequestering of carbon into this terrestrial pool. The final initiation of ice age pulses towards the end of inter-glacials, on the other hand, is attributed to the cyclic influx of cosmic dust to the Earth surface, which in turn regulates cloud formation and the incoming shortwave radiation. These shorter cycles have a frequency of c. 1000-1250 years and might be connected to sunspot or other low frequency solar variations. In a wider context the ice age cycling could be regarded as an interplay between terrestrial life on the high latitudes of the northern hemisphere and the marine subsurface life in the southeast. If the results presented here are correct, the present global warming might just be the early part of a new warm period such as the Bronze Age and the Roman and Medieval Warm periods. This could be caused by entry into another phase of decreasing influx rates of cosmic dust. The increasing concentrations of atmospheric carbon dioxide might have contributed to this warming but, most important of all, it might temporarily have saved us from a new ice age pulse. [ABSTRACT FROM AUTHOR]

Previous studies of clast macrofabrics in glacigenic deposits have concentrated on A-axis orientations and dips, and a variety of control samples are available based upon such measurements. Like clast A-axes, A/B planes will also tend to rotate to parallelism with the direction of shear and therefore should also provide meaningful data on the direction and cumulative impact of shear by the depositing/deforming medium (i.e. glacier ice). The measurement of A/B plane dip and orientation avoids the potential problem of the transverse orientations observed for clast A-axes and provides poles-to-plane data, thereby strengthening the modality of samples and providing clear visual impressions of stress directions. Such data also enable more significant inter-sample comparisons of fabric strength and clast dip angles, which are significant when assessing the impact of shearing in sediment genesis. We present data on clast A/B plane dip directions and angles from subglacial tills, glacitectonite continuums, subglacially lodged clasts and glacimarine/glacilacustrine deposits using traditional methods of statistical and graphical macrofabric analysis. These sample sets will serve as control data for future macrofabric analyses that utilize A/B planes. The separation of the unequivocally lodged clast component from subglacial till samples allows us to demonstrate the influence of deformation and ploughing in the relative weakening of till fabrics as proposed by some researchers. High angles of A/B plane dip in glacigenic subaqueous deposits appear to be well developed in the glacilacustrine setting investigated here, confirming previous studies based on A-axis dips, but less convincing in the glacimarine sediments of the Canadian Arctic, thereby widening the range of fabric strengths in subaqueous glacigenic deposits. Significant overlaps of A/B plane fabric shape envelopes reflect the strain history of subglacial and subaqueous depositional environments, which is unsurprising given the hybrid nature of glacigenic deposits, but the statistical isolation of the lodgement component from subglacial traction tills strongly suggests that the continuum of sample plots on modality/isotropy graphs reflects the range of strain histories in glacitectonites and subglacial traction till. [ABSTRACT FROM AUTHOR]

Climate change has reduced the extent and thickness of sea ice in the Arctic, making international shipping in the Northwest Passage a virtual certainty in the foreseeable future. Such future shipping raises the question of whether the Passage is or might become an international strait, with the consequent right of transit passage. This article examines the two possible legal bases for Canada's claim that the waters of the Canadian Arctic Archipelago are internal waters: a historic title and straight baselines. It also addresses the issue of the possible internationalization of the Passage, if Canada does not take preventive measures. Some such measures are recommended in the last part of the article. [ABSTRACT FROM AUTHOR]

This paper examines the Little Ice Age in the Scottish Highlands and Islands and uses documentary evidence to show its impact on the farm economy. It has three sections. The first examines how Highland climate may have changed during the Little Ice Age, and notes that increased storminess was probably as much a factor as lower annual mean temperatures. The second takes the most severe phase of the Little Ice Age, the Maunder Minimum. 1645–1715, and uses rests or eases of rent to show how it stressed the farm economy. The third examines evidence for the abandonment of land during the Maunder Minimum. As well as arguing that we need to see abandonment in its social as well as physical setting, it highlights the role played by the temporary abandonment of land and suggests that such abandonment along the western seaboard probably indicates tile impact of increased storminess. [ABSTRACT FROM AUTHOR]

A comparison is made of the bryophyte floras of two small maritime Antarctic islands lying at similar latitudes and with similar climates and glacial topographies, but differing markedly in their origins, geologies and derived soils. Signy Island (South Orkney Islands) is geologically complex with substrata ranging from strongly acidic schist to strongly alkaline marble and amphibolite, while Deception Island (South Shetland Islands) is volcanic with mildly alkaline lava, tuff, basalt and fine ash. Both islands are relatively low and approximately half ice-free. Signy has a long history of glacial fluctuations, allowing a wide range of cryptogamic community types to develop since the mid-Holocene (at least 5500 years ago), while most present substrata on Deception are very recent, following extensive habitat change resulting from eruptions in 1839–1842 and 1967–1970. The unstable nature of Deception's terrain greatly restricts habitat and plant community diversity. Nevertheless, both islands have the same number of bryophyte species and similar numbers that are exclusive to each island. Of the total of 81 moss and 19 liverwort species for both islands, only 36 and six species, respectively, are common to both islands. Much of this difference in species diversity is due to the greater substratum stability, abundance of surface water and the calcareous rocks and soils on Signy, and to geothermal activity at many sites on Deception. [ABSTRACT FROM AUTHOR]

In this paper we describe the dynamic behaviour of Salajekna, a valley glacier, over the last 200 years using terrestrial observations, in situ measurements, remote sensing observations and glacier reconstructions. The response time of the glacier was calculated using analytical models and field measurements. We were subsequently able to attribute specific dynamic responses to climate trends in the available climate record. The glacier's historical maximum extension was reached around 1880–1910 and was the result of a more continental climate with multi-modal airflows in the late 18th and early 19th centuries. A transition to more maritime conditions in the mid-19th century resulted in a near-continuous 20th century retreat before the glacier adjusted to a near-steady state. [ABSTRACT FROM AUTHOR]

Two well dated Holocene sediment records bordering the Denmark Strait region have been used to reconstruct past climate variability. The content of biogenic silica, clastic and organic material and moss in a lacustrine record from Lake N14 has been used to infer past variability in precipitation and temperature in southern Greenland. Sedimentologic and petrologic composition of sand in a shelf sediment record from the Djúpáll trough is used to infer past variability in the northwestern storm activity on northwestern Iceland, which probably also affected the inflow of polar waters from the East Greenland Current. Our evaluation of these records with a number of previous studies from the region documents Holocene climatic optimum conditions peaking between 8000 and 6500 calendar years before present (cal yr BP). Mid-Holocene climate deterioration set in around 5000 cal yr BP followed by a further marked setback around 3500 cal yr BP. A stacking of climate variability on a centennial timescale from previous studies in the area shows a fairly good correspondence to the timing of marked cold and warm events as evidenced from the Lake N14 and the Djúpáll trough records. Cooler periods are explained as the response to marked incursions of ice-laden polar water from the Arctic Ocean to the Denmark Strait region. Cool northerly and northwesterly winds along the East Greenland coast in relation to frequent strong atmospheric low pressure in the Barents Sea, coupled with strong high pressure over Greenland, would have favoured southward export of polar waters. A comparison with the proxy records of nuclide production (14C and 10Be) suggests that solar activity may have had some influence on the atmospheric pressure distribution in the Denmark Strait region. [ABSTRACT FROM AUTHOR]

Norway and New Zealand both experienced recent glacial advances, commencing in the early 1980s and ceasing around 2000, which were more extensive than any other since the end of the Little Ice Age. Common to both countries, the positive glacier balances are associated with an increase in the strength of westerly atmospheric circulation which brought increased precipitation. In Norway, the changes are also associated with lower ablation season temperatures. In New Zealand, where the positive balances were distributed uniformly throughout the Southern Alps, the period of increased mass balance was coincident with a change in the Interdecadal Pacific Oscillation and an associated increase in El Niño/Southern Oscillation events. In Norway, the positive balances occurred across a strong west-east gradient with no balance increases to the continental glaciers of Scandinavia. The Norwegian advances are linked to strongly positive North Atlantic Oscillation events which caused an overall increase of precipitation in the winter accumulation season and a general shift of maximum precipitation from autumn towards winter. These cases both show the influence of atmospheric circulation on maritime glaciers. [ABSTRACT FROM AUTHOR]

The ice block in Scalrişoara Cave, NW Romania, is preserved due to unusual climate and permafrost conditions within the cave. The air temperature in the cave is governed by the winter cold, the cooling effect of the ice block, and only to a minor extent influenced by summer temperatures. At present, the ice block is slowly thinning, but the present-day climate is sufficiently cold to preserve the permafrost conditions caused by the cold air trapped in the cave. In February 2003 a 22.5 m long ice core was recovered from the ice block. Approximately 200 ice layers have been identified by visual examination. Ice crystallographic analyses indicate a steady growth of ice crystals with depth and there is no sign of deformation. Carbon-14 dates on wood-related samples collected from a natural vertical exposure of the ice block indicate that the ice spans more than 1000 years. Observations on the exposure indicate that a basal melting phase may have occurred in the past. [ABSTRACT FROM AUTHOR]

A new high-resolution, alkenone-derived record of sea-surface temperature (SST) change covering the last 26000 years was obtained from the east-equatorial Atlantic off the Congo River. Temperature fluctuations correspond to climate change recorded in other marine and terrestrial archives of the region. The maximum temperature difference between 26000 years BP ago and the Holocene climate optimum around 6000 years Be was 4.3°C, corroborating other SST estimates from the same area. The coldest conditions were followed by a warming that began at 24000 calendar years BP, a time when Northern Hemisphere ice sheets were still at their maximal position. This comparatively early warming is in agreement with previous findings from the east-equatorial South Atlantic. After a relatively stable period between 21500 and 14500 calendar years Be, a second warming began at 14500 calendar years Be which coincides with the onset of the African Humid Period. A cool period at 11500 calendar years 8P halted this warming but the trend of increasing temperatures began again at 10000 calendar years BP, this time through large-scale oscillations. The warmest time, around 6000 calendar years BP, was followed by a modest cooling that coincides with the end of the African Humid Period and the onset of Neoglaciation on the African continent. Following this the record shows two distinct warming-cooling cycles during the late Holocene. [ABSTRACT FROM AUTHOR]

Crusts of white carbonate precipitate occur commonly on the upper surfaces of glacially sculptured Precambrian granites and gneisses in east-central Ellesmere Island. Radiocarbon dating of 21 such carbonate precipitates, from elevations between 50 m and 1050 m a.s.l., has yielded only Holocene ages. Two samples from Ellesmere Island, plus one from Inglefield Land, Greenland, have calibrated ages over 5000 years, the rest are younger. The formation of these deposits, mainly calcite and characterized by unusually heavy δ13C ratios (+3.36 to +15.18‰), has apparently been aided in some cases by the presence of bacteria, and some crusts seem to have developed where Ca-bearing minerals are more prevalent. In the case of Bache Peninsula and Cape Herschel, where the carbonate crusts are particularly abundant, the presence of calcareous till may have played a role as well. The carbonate crusts may be related to the presence of small, thin carapace ice caps, when such features formed at lower elevations than those at which they exist today. The more extensive cover of ice and snow is postulated to have existed during the latter, cooler part of the Holocene, especially during the period from 2500 to 100 years ago, deduced as a period of low melt from ice core studies on the Agassiz Ice Cap, 200 km to the north. The existence of carapace ice caps at lower elevations also agrees with the radiocarbon evidence for outlet glacier advances during the last 2000 years on both east and west margins of the Prince of Wales Icefield. Alternatively, the white carbonate crusts may be, to a large degree, the result of weathering processes. In either case they provide minimum ages for the exposed, ice-sculptured rock surfaces on which they occur. [ABSTRACT FROM AUTHOR]

The morphometry of 432 glacial cirques in the Maritime Alps (Western French-Italian Alps), studied over several years of fieldwork, was analysed with the use of a geographical information system. Some of the parameters automatically evaluated from digital elevation models required an objective and relatively new definition. In particular, cirque length was measured along a line that, from the threshold midpoint, splits the cirque into two equivalent surfaces; cirque width was automatically drawn as the longest line inscribed in the cirque and perpendicular to the length line. Significant correlations were found among the different factors and parameters analysed. In particular, cirque shape analysis showed that cirques develop allometrically in the three dimensions, i.e. more in length and width than in altitudinal range. Nevertheless cirques of the Maritime Alps have a regular, almost circular shape (meanL/Wvalue= 1.07). The correlations among length, width and area are all very high (r2= 0.8–0.9). In terms of size, cirques show a wide range in area from 0.06 to 5.2 km2 with a mean value of 0.4 km2. The largest cirques are found on SSW-facing slopes and at high elevations. Small cirques can be found at all altitudes but all those at high elevation are part of compound cirques at the main head valleys. Most cirques (37%) are characterized by a northern aspect; NE and SW are also frequent directions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Conflicting reports appear in the literature from geomorphic studies describing the colder Late Pleistocene environmental conditions of the Lesotho Highlands in southern Africa. Evidence is given for limited glaciation and/or periglacial conditions, with or without permafrost. An investigation of the distribution, morphometric attributes and surface weathering characteristics of relict openwork block accumulations in the area around Thabana-Ntlenyana, the highest summit in the range, supports the contention for a relatively arid periglacial environment during the Last Glacial period. A phase of enhanced block production is evident from the concentration of blocks in the upper layer of colluvium. Slope mobility on south-facing slopes is shown in the blockfield fabrics and the increase in downslope relative age of block surfaces. Block production and slope creep are attributed to depressed temperature conditions and seasonal freeze. Colluvium, within which blocks have been incorporated and superimposed, indicates that slope mantles predate the onset of the colder period and evidence militates against either deep snow cover or localised glaciation of south-facing slopes. [ABSTRACT FROM AUTHOR]

Well-known from permafrost hydrology, icings (naledorAufeis) are also frequently encountered at the margins of high-latitude glaciers. The morphology of a proglacial icing at Scott Turnerbreen in the Norwegian Arctic archipelago of Svalbard is described, and the process of formation is considered in detail. Ground thermal-regime modelling indicates an equilibrium permafrost depth of at least 200 m in the studied catchment, and it appears unlikely that groundwater contributes to icing formation. Meltwater flow through ice-marginal drainage channels is accompanied by estimated heat fluxes of up to about 190 W m−2, suggesting that stored meltwater may continue to percolate through thawed sub-channel sediments when surface runoff is absent during winter. A hydraulic conductivity of 6.9× 10−3 m s−1 is implied, which is consistent with other studies of glacier drainage systems. The long residence time of winter-draining meltwater, and solute rejection by refreezing water, account for high observed concentrations of solute in interstitial water in the icing. It has often been asserted that the presence of a proglacial icing indicates that a glacier is polythermal. However, as Scott Turnerbeen is entirely non-temperate, the presence of an icing cannot always be treated as a reliable guide to the thermal regime of a glacier. [ABSTRACT FROM AUTHOR]

Recent research has identified problems inherent in the identification and description of landforms. Morphologically similar small-scale glacial and periglacial landforms can be misinterpreted, thus hindering environmental reconstruction. This study reveals that a landform resembling a moraine at Stígárjökull, southern Iceland, is the product of both glacial deposition and mass movement. The landform has two distinct morphological and sedimentological components: a basal, lithologically diverse component, and an upper, lithologically homogenous component. Clast lithological analysis, particle shape and particle size measurements demonstrate that the basal component of the landform consists of sediment whose characteristics match nearby moraines. In contrast, the source of the upper component is a narrow outcrop of rock above the valley floor. Evidence suggests that frost-shattered material was transported across a perennial snow patch to a small moraine, leading to growth of the ‘moraine’. This combination of processes is unlikely to be unique, but the geological peculiarities of the field site permitted their identification. It is possible that many similar ‘moraines’ could be enlarged by subaerial feeding, leading to false reconstruction of glacier form and/or associated rates of erosion and sedimentation. Such polygenetic landform genesis therefore has implications for environmental reconstruction. [ABSTRACT FROM AUTHOR]

abstract A deep ice core drilled at Dome Fuji, East Antarctica was analyzed for the CO2 concentration using a wet extraction method in order to reconstruct its atmospheric variations over the past 320 kyr, which includes three full glacial–interglacial climatic cycles, with a mean time resolution of about 1.1 kyr. The CO2 concentration values derived for the past 65 kyr are very close to those obtained from other Antarctic ice cores using dry extraction methods, although the wet extraction method is generally thought to be inappropriate for the determination of the CO2 concentration. The comparison between the CO2 and Ca2+ concentrations deduced from the Dome Fuji core suggests that calcium carbonate emitted from lands was mostly neutralized in the atmosphere before reaching the central part of Antarctica, or that only a small part of calcium carbonate was involved in CO2 production during the wet extraction process. The CO2 concentration for the past 320 kyr deduced from the Dome Fuji core varies between 190 and 300 ppmv, showing clear glacial–interglacial variations similar to the result of the Vostok ice core. However, for some periods, the concentration values of the Dome Fuji core are higher by up to 20 ppmv than those of the Vostok core. There is no clear indication that such differences are related to variations of chemical components of Ca2+ , microparticle and acidity of the Dome Fuji core. [ABSTRACT FROM AUTHOR]

The bed topography of Jutulstraumen is of interest in connection with glaciological modelling for climatic and geological studies. During the Norwegian Antarctic Research Expedition 1996/97 (NARE 96/97) 971 km of bed topography profiles were mapped using ground-penetrating radar (GPR) and a global positioning system (GPS). As additional information to the GPR data for the map compilation, surface features connected to the bed topography were identified in optical satellite images, and relative velocities derived from interferometric synthetic aperture radar (INSAR) data were interpreted using principles of ice flow related to the bed topography. Grids (250 x 250 m) covering the area 73° to 71°S, 0° to 4°E of bed topography and ice thickness were developed. Several observations are confirmed by the independent data sets. The Jutulstraumen outlet glacier shows extreme topography with subglacial plateaus and deep valleys due to faulting. A previously unmapped valley in connection with the fault system is identified. The data sets provide evidence of a grounding line position 6-20 km further inland than previously expected, and a trough occurs 60 km up-glacier from this position. [ABSTRACT FROM AUTHOR]

Examines the sedimentary and cryogenic features indicating a periglacial aeolian sand sheet in Stuart Shelf, South Australia. Determination of the dominant paleowind direction; Importance of periglacial aeolian activity during the Neoproterozoic glaciation; Generations of periglacial cryogenic structures.

ABSTRACT. The sedimentological characteristics of in situ and paraglacially reworked till are compared at recently deglaciated sites in Norway. Glacigenic deposits reworked by debris flows are shown to retain many of the characteristics of the parent sediments, and cannot readily be distinguished from in situ till in terms of fabric strength or type, clast imbrication, shape, angularity or texture, matrix granulometry or packing. Paraglacially reworked sediments appear to differ from in situ tills only in terms of preferred clast orientation (down flow rather than downvalley) and their structural and lithofacies characteristics. These criteria are employed to differentiate paraglacial sediments from unreworked tills exposed in valley-side sections. The stratigraphic relations between these indicate glacial reworking of earlier paraglacial sediments as well as paraglacial remobilisation of glacigenic deposits, indicating cyclic alternation of glacial and paraglacial sediment transport. [ABSTRACT FROM AUTHOR]

ABSTRACT. We present four glacial geomorphic maps of Llanquihue drift in the region of the southern Lake District, Seno Reloncavi, and the eastern half of northern Isla Grande de Chiloe, Chile. These maps form the basis of an interdisciplinary research project to establish a paleoclimate reconstruction of the last glacial cycle in the middle latitudes of the Southern Hemisphere. Therefore we stressed morphologic rather than lithologic units in our mapping program in order to delineate the glacial geomorphic forms that are surface manifestations of former ice-marginal fluctuations. The resulting maps show the lobate shape and low surface slopes of the former piedmont glaciers that, at the last glacial maximum, spread westward from the Andes into the Valle Central to fill Lago Puyehue, Lago Rupanco, Lago Llanquihue, Seno Reloncavi, Golfo de Ancud, and northern Gulfo Corcovado. These maps are the framework to tie together in this volume the stratigraphic sections and radiocarbon samples from within the Llanquihue moraine belts as well as the pollen cores from surface mires on the belts. [ABSTRACT FROM AUTHOR]

Two Woodfordian glaciated regions in Wisconsin were analyzed to determine the impact of variable loess thickness and contrasting till texture on soil pattern and landscape properties. Each region consisted of a ground moraine/end moraine/outwash plain landform sequence. Data were compiled from soil and topographic maps. In addition to using standard methods of soilscape analysis. I used a natural soil drainage index, calculated from taxonomic data, to determine regional variability and pattern of soil wetness. Results indicate that soilscape variation within each region was large. There were no statistically significant differences, therefore, that could be attributed to known soil- forming processes or to parent material variability. Stratifying the data by geomorphic subregion rather than by region reduced the within-unit soil variability and resulted in numerous significant soilscape differences between subregions. The implication is that soilscape variability is large at the regional scale but converges rapidly with decreasing size of study area. [ABSTRACT FROM AUTHOR]

Measurements of discharge, reach morphology, and cross-section morphology in supraglacial streams on the Juneau Icefield reveal controlling variables that have analogous counterparts in alluvial streams. Downward sky radiation imparts a strong diurnal pattern to supraglacial runoff generated by saturated slush flows, precipitation and melting, channel erosion, and spillover from water-filled moulins, crevasses, and supraglacial lakes. Supraglacial streams are generated when runoff is concentrated on glacier slopes and rates of incision exceed rates of glacier surface ablation. Streams leave the surface via moulins and crevasses where the water becomes part of the englacial and subglacial drainage systems. Meander systems develop and migrate downstream, driven by thermal erosion with heat supplied by climatic and hydrologic sources. Sinuosity attains a maximum value, in the absence of other roughness factors, when high stream power is imposed from an adjacent upstream reach. Form-process relationships for supraglacial meanders are similar to those for alluvial streams in spite of the contrast in time and scale of development. At-a-station hydraulic geometry for supraglacial streams serves to identify channel adjustments to changing discharge not unlike those for narrow-deep, straight alluvial streams. Daily formation of longitudinal grooves in channel walls leaves a record of daily flow and yields critical information regarding channel enlargement ratios. Fluvial adjustment toward equilibrium conditions involves all elements of channel roughness and cannot be analyzed using any single indicator such as channel pattern, cross-sectional shape, or materials involved. [ABSTRACT FROM AUTHOR]

ABSTRACT. Documentary data provide long time series and sometimes high-resolution, detailed data from historical times to the present and can give valuable information about palaeoclimate, and for the prediction of future climates. In this paper, documentary data containing qualitative information on climate, in the form of a diary written by the farmer I.G. Grude, and two newspapers, were used for the reconstruction of the palaeoclimate at Jaeren, in the county of Rogaland, in southwestern Norway, during the period 1821-50. An index method to quantify the qualitative climate data was developed and used for a low-resolution reconstruction of winter, summer and annual temperatures. A high-resolution climate reconstruction of temperature and precipitation for the winter of 1837/38 is also presented, making use of a method that keeps the climate data in a qualitative form. The climate reconstructions are compared to an instrumental temperature series from Bergen, for the same period. The two data sets are in good agreement except for summer temperature (annual temperature: r = 0.75, winter temperature: r = 0.77, summer temperature: r = 0.44). Compared to average temperatures during 1961-90, the instrumental data from Bergen during the 1821-50 period show slightly different temperatures: annual average was 0.3 Celsius lower, winter 0.4 Celsius lower, and summer 0.1 Celsius lower than at present, implying conditions consistent with the "Little Ice Age" climate. [ABSTRACT FROM AUTHOR]

Three drainage intensity regions of the Allegheny Plateau formed on renewed surfaces in response to conditions imposed by glacial and periglacial processes. Because of the severe transformation of an antecedent surface into streamlined form, postglacial stream concentrations are highest in the north and decrease southward as the degree of glacial modification diminishes, permitting the survival of relict landforms better adapted to normal erosional processes. Southward differences in surface mantle characteristics consonantly affect the generation of drainage line. [ABSTRACT FROM AUTHOR]

Colluvial mantles on the mountains of southwestern United States are believed to have formed during colder climates associated with the last glaciation. They imply mean temperatures 10-11°C. lower than those of today and a depression of the timber line by 1,300-1,400 meters. Evaporation rates were about half the present values and by estimating runoff it is possible to reconstruct the full-glacial hydrologic budget of Pleistocene closed lakes. Precipitation was eighty to ninety percent of present values and there was no glacial pluvial. Pollen data can be reconciled with the proposed cold dry climate which has modem homoclimes at higher altitudes and latitudes. [ABSTRACT FROM AUTHOR]

Investigations near some of the icecaps of central Iceland show that pressure and winds are markedly affected by the presence of the icecaps under various synoptic conditions. The main effect is of wave formation and descent of dry air, coming predominantly from Polar or Arctic air masses, and the descent of this air is associated with a belt of severe soil erosion in south and central Iceland. A similar effect can also be detected in northern Iceland.