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High-precision Schmidt-hammer exposure-age dating ( SHD) is applied to ice-cored moraine-ridge complexes at three high-alpine glaciers in Jotunheimen and Breheimen, southern Norway. Local calibration curves were established using moraine ridges dating from the last 50 years and bedrock surfaces deglaciated ∼9700 years ago. SHD ages, with 95% statistical confidence intervals, ranged from 3920 ± 790 years to a negative (futuristic) age of -890 ± 580 years at Gråsubreen, 420 ± 700 to 260 ± 710 years at Vesle-Juvbreen and 2250 ± 450 to 1605 ± 410 years at Østre Tundradalskyrkjabreen. Negatively skewed R-value distributions were interpreted as the result of weathered boulders from reworked surfaces. This leads to the interpretation of these SHD ages as maximum estimates of moraine-ridge age. Østrem's hypothesis (that the proximal ridges are the oldest and survived being overridden many times) is rejected on the basis of our SHD ages. Although ice-cored moraine ridges resemble the flow structures of rock glaciers, Barsch's hypothesis (that these ice-cored moraine complexes are rock glaciers) is also rejected. Instead, the ice-cored moraine-ridge complexes are considered to be glaciotectonic structures produced by the interaction of polythermal glaciers and alpine permafrost over the late Holocene. All the individual ridges were essentially formed during the ' Little Ice Age' glacier advance from material deposited earlier by multiple neoglacial events. The considerable size of the moraine complexes is attributed not only to the accumulation of material from these different events over a long period of time but also to their survival in the landscape during phases of glacier retreat when ice cores do not melt and fluvial and other destructive processes remain ineffective in the permafrost environment. [ABSTRACT FROM AUTHOR]

Chronological studies applying Schmidt-hammer exposure-age dating (SHD) were performed on six glacier forelands in the western part of the Southern Alps, New Zealand. Although lithological heterogeneity prevented a regional age-calibration curve to be established, local age-calibration curves for La Perouse Glacier and Strauchon Glacier could be derived. They show similar linear equations and trends/slopes and enabled a preliminary assessment of the representativeness of individual 10Be terrestrial cosmogenic nuclide dating (TCND)-ages obtained from the other forelands. No mid- and early-Holocene advance periods were detected. Clusters of moraine ages date around 2800, 1850–1450, and 1100–900 years ago, followed by the ‘Little Ice Age’ commencing c. 500 years ago. There is no good agreement with earlier radiocarbon-based studies and recently published TCND-chronologies. As it will be outlined, this partly could be the result of different approaches to the palaeoclimatic interpretation of the dated samples. The results obtained from this recent study do not support an elsewhere proposed general asynchronous glacier behaviour between the mid-latitudinal Northern and Southern hemispheres. [ABSTRACT FROM AUTHOR]

Matthews, J. A. & Winkler, S. 2010: Schmidt-hammer exposure-age dating (SHD): application to early Holocene moraines and a reappraisal of the reliability of terrestrial cosmogenic-nuclide dating (TCND) at Austanbotnbreen, Jotunheimen, Norway. Boreas, 10.1111/j.1502-3885.2010.00178.x. ISSN 0300-9483. Schmidt-hammer exposure-age dating (SHD) and terrestrial cosmogenic-nuclide dating (TCND) are complementary techniques that can be used for mutual testing. SHD is low-cost but requires local control points of known age and may be affected by local geological variation and other environmental factors that influence weathering rates. TCND is vulnerable to the occurrence of anomalous boulders, other geomorphological uncertainties and the effects of snow-shielding at high altitudes. Both techniques are sensitive to post-depositional disturbances if other than solid bedrock is sampled. SHD was applied to two moraine ridges beyond the Little Ice Age limit of Austanbotnbreen in the Hurrungane massif, southern Norway. Independent regional and experimental local age-calibration curves were used to reappraise previous TCND results. Neither the two boulder surfaces nor their proximal bedrock surfaces could be differentiated statistically in terms of SHD exposure ages or their mean R-values (±95% confidence intervals), which ranged from 40.73±1.72 to 43.34±0.69. The best of the independent regional-calibration curves produced SHD exposure ages of 9413±723 and 9304±602 years, which are consistent with moraine formation early ( c. 10.2 ka) and late ( c. 9.7 ka) within the late-Preboreal Erdalen Event. The current precision of SHD, as reflected in 95% confidence intervals of ±500-900 years, enables rejection of a Finse Event ( c. 8.2 ka) age for either moraine. Results are consistent with a retracted Austanbotnbreen between the Erdalen Event and the Little Ice Age, and a modified model of Neoglaciation. [ABSTRACT FROM AUTHOR]

Abstract: The formation of terminal moraines dating from glacier advances during the A.D. 1990s was investigated at six temperate glaciers in the Jostedalsbreen and Jotunheimen regions of southern Norway. Morphological and sedimentological information was analysed and combined with detailed observations, photographic evidence, and length variation measurements. Bulldozing (pushing) of proglacial sediments was the predominant process at the low-lying glacier termini of the debris-free outlets of the Jostedalsbreen ice cap. Evidence for bulldozing includes the relocation and rotation of boulders and the presence of lichen-covered boulders in the distal slopes of moraines. Differences in moraine sedimentology between the individual sites are attributed to variations in the pre-existing material pushed up, rather than to specific processes. In Jotunheimen, several modes of moraine-ridge formation were active: dumping of supraglacial debris and the marginal freezing-on and subsequent melting-out of subglacial sediment slabs were more important than bulldozing at some sites and in some years. Low air temperatures in winter at the higher altitude glacier termini enabled freezing-on to occur. However, the forelands are below the lower limit of discontinuous permafrost and evidence of thrusting is absent. Whereas discrete terminal moraine ridges at Jostedalsbreen are related to (seasonal) advances, the less dynamic glaciers of Jotunheimen allow the accretion of successive ridges during consecutive years. No single regional mode of moraine formation is characteristic for southern Norway: several processes are involved depending on individual glacier morphology and dynamics, the glaciological regime, and environmental conditions (especially climate) on the glacier forelands. The importance of specific processes varies within and between glacier forelands. Thus, spatial and temporal variation and local individuality has to be taken into account in the interpretation of moraine-ridge formation. Similar variability is likely to have been characteristic of terminal moraines deposited during the “Little Ice Age” and earlier in the Quaternary. [Copyright &y& Elsevier]

ABSTRACT. Owing to increased winter balances especially since AD 1988/89, almost all valley outlet glaciers of Jostedalsbreen in western Norway are experiencing the largest advance since that of the early 18th century, the regional "Little Ice Age" maximum. Brigsdalsbreen advanced 441 m between 1987 and 1997. By the end of this period, the glacier had reached the outlet of the proglacial lake Brigsdalsvatnet, ploughing into unfrozen, fine-grained, water-soaked glaciolimnic sediments from the lake bottom and forming frontal moraines. These moraines are characterised by a lack of internal structures and preferred fabric. Owing to the strong advance, the moraine morphology is constantly changing, leaving only temporary moraine ridges. Observations made along the glacier front suggest that the formation of these moraines can best be described as "bulldozed moraines", since the term push moraine, commonly associated with advancing glaciers, should be restricted to permafrost environments. Different processes involved in moraine formation at frontal and lateral glacier margins result from variations in proglacial sediment properties, microrelief and glacier dynamics. Among these processes, large boulders left in the proglacial areas are pushed forward, forming pressure ridges on the distal side. Some of the largest boulders (c. 80-120 m[sup 3]) are overturned or rotated by the glacier. [ABSTRACT FROM AUTHOR]

Surface exposure–age dating was applied to rock surfaces associated with ice‐marginal moraines at elevations of ~1520–1780 m a.s.l. on the slopes of Galdhøpiggen and Glittertinden, the two highest mountains in Scandinavia located in the Jotunheimen mountains of central southern Norway. This is important for understanding the pattern and timing of wastage of the Scandinavian Ice Sheet at the Younger Dryas–Holocene transition. Cosmogenic exposure dating (here 10Be dating) of boulders from the moraine ridges yielded overall mean ages (corrected for glacio‐isostatic uplift, surface erosion and snow shielding) of ~11.6 ka from Galdhøpiggen and ~11.2 ka from Glittertinden. Similar 10Be ages were also obtained from additionally collected proximal and distal erratic boulders and bedrock samples. These enabled age calibration of Schmidt‐hammer R‐values and independent Schmidt‐hammer exposure‐age dating (SHD) of the moraine ridges, which yielded comparable mean SHD ages of ~10.8 and ~10.6 ka from the Galdhøpiggen and Glittertinden sites, respectively. Taking account of the age resolution and other limitations of both dating techniques, the results suggest that the two sets of moraines have approximately the same age but that neither technique can distinguish unambiguously between moraine formation in the late Younger Dryas or Early Holocene. Together with features of moraine‐ridge morphology and estimates of equilibrium‐line altitude depression of ~360–575 m (corrected for land uplift), the results imply moraine formation during short‐lived re‐advances of active glaciers, at least the lower reaches of which were warm‐based. It is concluded that the local glaciers remained active and advanced during deglaciation either very late in the Younger Dryas or very early in the Holocene, possibly in response to the Preboreal Oscillation at ~11.4 ka. The study supports the concept of a thin Younger Dryas ice sheet and places time constraints on the timing of final deglaciation in southern Norway. [ABSTRACT FROM AUTHOR]

Research on mountain glaciations has a long history and in the light of current global change, they are increasingly recognised as highly important palaeoclimatic archives for the immediate and more distant geological past. One of the most important leaps forward with the investigation of mountain glaciations during the past 2 decades was substantial improvement achieved within the field of numerical age dating techniques, in particular progress of surface exposure dating using cosmogenic radionuclides (CRN). This development has definitely given the entire research field new momentum. Unfortunately, this methodological progress is in many cases not matched by the recommended necessary level of precautions regarding the interpretative steps with the reconstruction of Holocene glacier chronologies. Improved precision and accuracy with numerical dating techniques comes often with an increasing lack of attention with the geomorphological analysis of the dated landforms. With recent studies it has subsequently become more popular to outline moraines primarily based on individual CRN boulder age clusters without detailed geomorphological mapping or examination. Such an attempt has also been conducted on Holocene glacier forelands in Aoraki/Mt.Cook National Park where a substantial number of CRN boulders ages have been employed to identify and label numerous "moraines". Subsequently, arithmetic means of CRN ages for these apparent "moraines" were linked to individual glacier advances and palaeoclimatically interpreted accordingly. A sound geomorphological analysis of the studied glacier foreland does, however, reveal that this procedure is actually erroneous. Among the problems identified are (a) inclusion of hugely overprinted moraine remnants that lack proper characterisation, (b) wrong subdivision of moraine segments belonging to one defined individual moraines, and (c) mismatching of apparent CRN ages for moraine segments that morphologically need to correspond for any meaningful reconstruction of former marginal positions. A revision of this particular glacier chronology provides major implications for any subsequent palaeoclimatic interpretation as the number of reliably documented neoglacial events decrease from 9 to 5.The value of geomorphological analysis in the context of investigating mountain glaciations is, however, not primarily restricted to chronological approaches. It may also provide assistance with the conceptual context for mechanisms of deglaciation patterns or long-term landscape evolution. In the upper Waimakariri River catchment following a Late Glacial readvance dated to c. 17.5 ka ago, a lake dammed by the related moraine system and debris-covered dead ice should have existed for many centuries before it subsequently drained. That lake would naturally have influenced both the immediate deglaciation mechanism and landform evolution post-LGM. Despite introduced during the 1950s, the concept of this particular palaeo-lake has never been exposed to any detailed geomorphological analysis yet. Whereas the existence of a post-LGM palaeo-lake itself remains out of question, the proposed link to glacier retreat following a Late Glacial re-advance is unrealistic in light of a logical time sequence for individual elements of the local landform assemblage. The lake needs to be younger and postdate Deglaciation in this section of the Waimakariri River.Summarising, detailed geomorphological analysis is indispensable with any attempt to investigate mountain glaciations. [ABSTRACT FROM AUTHOR]

In southern Norway, early-Holocene climatically induced glacier expansion episodes have been recognised at ~11.1, 10.5, 10.2, 9.7 and 8.2 ka, but the only convincingly dated, single- or doubleridged moraines are those associated with the regional Erdalen Event (i.e., ~10.2-9.7 ka). We applied three numerical-age dating techniques to sequences of up to five moraine ridges deposited by the former Sognefjell ice cap and by Styggedalsbreen, a large cirque glacier in the nearby Hurrungane massif. On inner and outer ridges and relict patterned ground proximal to the moraines, six 10Be and eight Schmidt hammer (SHD) surface exposure ages were obtained. Thirteen radiocarbon dates were obtained from stream-bank mire sediments proximal to the Sognefjell moraines. The basal date is similar to those from cores in an adjacent lake indicating disappearance of the Sognefjell ice-cap immediately following the Erdalen Event. Three of four SHD results, and one of three 10Be surface exposure ages from the Sognefjell moraines support this. At Styggedalsbreen, two of three 10Be surface exposure ages lie between the 8.2 ka (Finse) and Erdalen Event, though 1 s dating uncertainties only overlap with the former: the third is clearly affected by cosmogenic nuclide inheritance. SHD results also suggest the younger event, but this is attributed to lithological differences between the Schmidt-hammer calibration site and the sampled moraine boulders. Considering the chronological evidence as a whole, supported by equilibrium-line altitude (ELA) calculations for Styggedalsbreen, we conclude that the moraines were formed by up to five short but distinct fluctuations of these ice masses during the Erdalen Event. This indicates more complex decadal- to centennial-scale glacier variations and climatic perturbations within the Erdalen Event than previously recognised. The implied exceptional glaciological sensitivity to climate variability is attributed to local topographic factors causing glacial fluctuations in response to relatively small ELA changes. [ABSTRACT FROM AUTHOR]

The article discusses the preservation of periglacial and glacial landforms of South Island (Te Wai Pounamu) of New Zealand (Aotearoa). It cites on the studies using cosmogenic nuclide of moraines to recostruct palaeoclimatic conditions in the country. The article also discusses that the studies are used as basis for climatic analysis and interchemispheric correlations.

Medial moraines form important pathways for sediment transportation in valley glaciers. Despite the existence of well-defined medial moraines on several glaciers in the New Zealand Southern Alps, medial moraines there have hitherto escaped attention. The evolving morphology and debris content of medial moraines on Franz Josef Glacier and Fox Glacier on the western flank of the Southern Alps is the focus of this study. These temperate maritime glaciers exhibit accumulation zones of multiple basins that feed narrow tongues flowing down steep valleys and terminate ~ 400 m above sea level. The medial moraines at both glaciers become very prominent in the lower ablation zones, where the medial moraines widen, and develop steeper flanks coeval with an increase in relative relief. Medial moraine growth appears somewhat self-limiting in that relief and slope angle increase eventually lead to transport of debris away from the medial moraine by mass-movement-related processes. Despite similarities in overall morphologies, a key contrast in medial moraine formation exists between the two glaciers. At Fox Glacier, the medial moraine consists of angular rockfall-derived debris, folded to varying degrees along flow-parallel axes throughout the tongue. The debris originates above the ELA, coalesces at flow-unit boundaries, and takes a medium/high level transport pathway before subsequently emerging at point-sources aligned with gently dipping fold hinges near the snout. In contrast at Franz Josef Glacier, the medial moraine emerges farther down-glacier immediately below a prominent rock knob. Clasts show a mix of angular to rounded shapes representing high level transport and subglacially transported materials, the latter facies possibly also elevated by supraglacial routing of subglacial meltwater. Our observations confirm that a variety of different debris sources, transport pathways, and structural glaciological processes can interact to form medial moraines within New Zealand's Southern Alps. [ABSTRACT FROM AUTHOR]

The inland valleys of New Zealand’s South Island were heavily glaciated during the last glacial cycle. Subsequent fluvial incision has eroded out glacial deposits from the valleys in many locations, making it difficult to reconstruct glacial dynamics and chronology. The Brabazon and Butler Downs lie in a fault-controlled intra-montaine basin that has been largely protected from fluvial erosion and the area contains extensive evidence for multiple glacial margins. This paper presents a detailed glacial geomorphology map of the Brabazon and Butler Downs at a scale of 1:20,000. Glacial landforms have been mapped and subdivided into three main zones: an upper zone distinguished by a flight of kame terraces, a middle zone containing kettles and meltwater channels, and a lower zone of lateral moraines. The new map provides insight into former glacial environments in the region and provides a related framework for future paleoclimate reconstructions. [ABSTRACT FROM PUBLISHER]

Lichenometric evidence and Schmidt hammer R-values are used to date Holocene moraine sequences in front of six high-altitude (> 1500 m) glaciers in Breheimen, central southern Norway. At three glacier forelands with southerly aspects (Høgsetbreen, Vestre Høybre and Østre Høybre), relatively small (≤ 4 m high) discrete boulder moraine ridges are shown to date from the 'Little Ice Age'. The remaining three glaciers (Østre Tundradalskyrkjabre, Nordre Tundradalskyrkjabre and Hestdalshøgdibreen), with northerly or easterly aspects and large, multiridged, rampart-like moraine complexes (15–30 m), thought to be ice-cored and of the 'push-deformation' type, lie above the local altitudinal limit of permafrost. Negatively skewed R-value distributions from these moraine complexes provide critical evidence for pre-'Little Ice Age' glacier expansion as they indicate the survival of long-weathered boulders on moraine surfaces where late-lying snow may reduce or prevent lichen growth. Formation of the moraine complexes appears to have begun in Preboreal times, most likely during the Erdalen Event, but much of their present character was determined by repeated Neoglacial glacier expansion, moraine deformation and ridge formation in the late Holocene, culminating in the 'Little Ice Age' readvance. [ABSTRACT FROM AUTHOR]