Early-Holocene glacier fluctuations of northern Grovabreen, western Norway

The Holocene ◽  
2018 ◽  
Vol 29 (2) ◽  
pp. 187-196 ◽  
Author(s):  
Asbjørn Rune Aa ◽  
Eivind Sønstegaard

Marginal moraines on the northern side of Grovabreen, a plateau glacier in inner Sunnfjord, Western Norway, have been mapped and morphostratigraphically correlated with the Erdalen Event and possibly the Finse Event and the ‘Little Ice Age’. Schmidt-hammer exposure-age dating was used to evaluate the age of the most distinct marginal moraines by measuring the degree of surface weathering on boulders. The lithostratigraphy of lake sediments was analysed in a core from Dalevatnet in order to correlate this stratigraphy with the marginal moraines in the catchment area of the lake and reconstruct the early-Holocene history of Grovabreen. The lake catchment was deglaciated at 10,750 cal. yr BP. Two readvances of an outlet glacier in Fagredalen were dated to between 10,340 and 9960 cal. yr BP, correlated with the two-peaked Erdalen Event. A readvance shortly after 8450 cal. yr BP can most probably be correlated with the 8200 cal. yr BP Finse Event.

Author(s):  
VALENTIN BURKI ◽  
LOUISE HANSEN ◽  
OLA FREDIN ◽  
THORBJØRN A. ANDERSEN ◽  
ACHIM A. BEYLICH ◽  
...  

The Holocene ◽  
2018 ◽  
Vol 28 (10) ◽  
pp. 1609-1622 ◽  
Author(s):  
Helene Løvstrand Svarva ◽  
Terje Thun ◽  
Andreas Joachim Kirchhefer ◽  
Atle Nesje

A ring-width Pinus sylvestris chronology from Sogndal in western Norway was created, covering the period AD 1240–2008 and allowing for reconstruction of monthly mean July temperatures. This reconstruction is the first of its kind from western Norway and it aims to densify the existing network of temperature-sensitive tree-ring proxy series to better understand past temperature variability in the ‘Little Ice Age’ and diminish the spatial uncertainty. Spatial correlation reveals strong agreement with temperatures in southern Norway, especially on the western side of the Scandinavian Mountains. Five prominent cold periods are identified on a decadal timescale, centred on 1480, 1580, 1635, 1709 and 1784 and ‘Little Ice Age’ cooling spanning from 1450 to the early 18th century. High interannual and decadal agreement is found with an independent temperature reconstruction from western Norway, which is based on data from grain harvests and terminal moraines. The reconstructed temperatures also correlate with other tree-ring-based temperature reconstructions from Fennoscandia, most strongly with data from central Sweden. Tree growth in Sogndal is correlated to the Scandinavian teleconnection index in the summer months, at least in the last half of the 20th century, and is positively correlated to the summer expression of the North Atlantic Oscillation in the early half of the 20th century. A significant response to major volcanic forcing in the Northern Hemisphere was found, and extreme years seem to be related to the dominance of high and low geopotential height that in turn represents variability in the path of the storm tracks over Fennoscandia. When compared with the variation in frontal positions with time of Nigardsbreen, an eastern outlet glacier from the Jostedalsbreen glacier in western Norway, cold summers in the early 18th century relates to the culmination of a rapid glacial advance that lead up to the 1748 ‘Little Ice Age’ maximum extent.


The Holocene ◽  
2010 ◽  
Vol 20 (6) ◽  
pp. 849-861 ◽  
Author(s):  
Catalina González ◽  
Ligia Estela Urrego ◽  
José Ignacio Martínez ◽  
Jaime Polanía ◽  
Yusuke Yokoyama

2017 ◽  
Vol 54 (11) ◽  
pp. 1153-1164 ◽  
Author(s):  
B.H. Luckman ◽  
M.H. Masiokas ◽  
K. Nicolussi

As glaciers in the Canadian Rockies recede, glacier forefields continue to yield subfossil wood from sites overridden by these glaciers during the Holocene. Robson Glacier in British Columbia formerly extended below tree line, and recession over the last century has progressively revealed a number of buried forest sites that are providing one of the more complete records of glacier history in the Canadian Rockies during the latter half of the Holocene. The glacier was advancing ca. 5.5 km upvalley of the Little Ice Age terminus ca. 5.26 cal ka BP, at sites ca. 2 km upvalley ca. 4.02 cal ka BP and ca. 3.55 cal ka BP, and 0.5–1 km upvalley between 1140 and 1350 A.D. There is also limited evidence based on detrital wood of an additional period of glacier advance ca. 3.24 cal ka BP. This record is more similar to glacier histories further west in British Columbia than elsewhere in the Rockies and provides the first evidence for a post-Hypsithermal glacier advance at ca. 5.26 cal ka BP in the Rockies. The utilization of the wiggle-matching approach using multiple 14C dates from sample locations determined by dendrochronological analyses enabled the recognition of 14C outliers and an increase in the precision and accuracy of the dating of glacier advances.


2014 ◽  
Vol 8 (4) ◽  
pp. 1497-1507 ◽  
Author(s):  
S. A. Khan ◽  
K. K. Kjeldsen ◽  
K. H. Kjær ◽  
S. Bevan ◽  
A. Luckman ◽  
...  

Abstract. Observations over the past decade show significant ice loss associated with the speed-up of glaciers in southeast Greenland from 2003, followed by a deceleration from 2006. These short-term, episodic, dynamic perturbations have a major impact on the mass balance on the decadal scale. To improve the projection of future sea level rise, a long-term data record that reveals the mass balance beyond such episodic events is required. Here, we extend the observational record of marginal thinning of Helheim and Kangerdlugssuaq glaciers from 10 to more than 80 years. We show that, although the frontal portion of Helheim Glacier thinned by more than 100 m between 2003 and 2006, it thickened by more than 50 m during the previous two decades. In contrast, Kangerdlugssuaq Glacier underwent minor thinning of 40–50 m from 1981 to 1998 and major thinning of more than 100 m after 2003. Extending the record back to the end of the Little Ice Age (prior to 1930) shows no thinning of Helheim Glacier from its maximum extent during the Little Ice Age to 1981, while Kangerdlugssuaq Glacier underwent substantial thinning of 230 to 265 m. Comparison of sub-surface water temperature anomalies and variations in air temperature to records of thickness and velocity change suggest that both glaciers are highly sensitive to short-term atmospheric and ocean forcing, and respond very quickly to small fluctuations. On century timescales, however, multiple external parameters (e.g. outlet glacier shape) may dominate the mass change. These findings suggest that special care must be taken in the projection of future dynamic ice loss.


2017 ◽  
Vol 21 (4) ◽  
pp. 190-196
Author(s):  
Jan Czempiński ◽  
Maciej Dąbski

AbstractThe aim of this article is to show the results of the lichenometrical and Schmidt hammer measurements performed in 2015 during the AMADEE-15 Mars Mission Simulation in the Ötztal Alps in order to test the capabilities of analogue astronauts and collect information on the geomorphic history of the study area since the Little Ice Age (LIA). The results obtained differ significantly from our expectations, which we attribute to differences in the field experience of participants and the astronauts’ technical limitations in terms of mobility. However, the experiments proved that these methods are within the range of the astronauts’ capabilities. Environmental factors, such as i) varied petrography, ii) varied number of thalli in test polygons, and iii) differences in topoclimatic conditions between the LIA moraine and the glacier front, further inhibited simple interpretation. The LIA maximum of the Kaunertal glacier occurred in AD 1850, and relative stabilization of the frontal part of the rock glacier occurred in AD 1711.


2018 ◽  
Vol 12 (7) ◽  
pp. 2249-2266 ◽  
Author(s):  
Nadine Steiger ◽  
Kerim H. Nisancioglu ◽  
Henning Åkesson ◽  
Basile de Fleurian ◽  
Faezeh M. Nick

Abstract. Rapid retreat of Greenland's marine-terminating glaciers coincides with regional warming trends, which have broadly been used to explain these rapid changes. However, outlet glaciers within similar climate regimes experience widely contrasting retreat patterns, suggesting that the local fjord geometry could be an important additional factor. To assess the relative role of climate and fjord geometry, we use the retreat history of Jakobshavn Isbræ, West Greenland, since the Little Ice Age (LIA) maximum in 1850 as a baseline for the parameterization of a depth- and width-integrated ice flow model. The impact of fjord geometry is isolated by using a linearly increasing climate forcing since the LIA and testing a range of simplified geometries. We find that the total length of retreat is determined by external factors – such as hydrofracturing, submarine melt and buttressing by sea ice – whereas the retreat pattern is governed by the fjord geometry. Narrow and shallow areas provide pinning points and cause delayed but rapid retreat without additional climate warming, after decades of grounding line stability. We suggest that these geometric pinning points may be used to locate potential sites for moraine formation and to predict the long-term response of the glacier. As a consequence, to assess the impact of climate on the retreat history of a glacier, each system has to be analyzed with knowledge of its historic retreat and the local fjord geometry.


2006 ◽  
Vol 65 (1) ◽  
pp. 70-77 ◽  
Author(s):  
Neil F. Glasser ◽  
Stephan Harrison ◽  
Susan Ivy-Ochs ◽  
Geoffrey A.T. Duller ◽  
Peter W. Kubik

AbstractThis paper presents data on the extent of the North Patagonian Icefield during the Late Pleistocene–Holocene transition using cosmogenic nuclide exposure age and optically stimulated luminescence dating. We describe geomorphological and geochronological evidence for glacier extent in one of the major valleys surrounding the North Patagonian Icefield, the Rio Bayo valley. Geomorphological mapping provides evidence for the existence of two types of former ice masses in this area: (i) a large outlet glacier of the North Patagonian Icefield, which occupied the main Rio Bayo valley, and (ii) a number of small glaciers that developed in cirques on the slopes of the mountains surrounding the valley. Cosmogenic nuclide exposure-age dating of two erratic boulders on the floor of the Rio Bayo valley indicate that the outlet glacier of the icefield withdrew from the Rio Bayo valley after 10,900 ± 1000 yr (the mean of two boulders dated to 11,400 ± 900 yr and 10,500 ± 800 yr). Single-grain optically stimulated luminescence (OSL) dating of an ice-contact landform constructed against this glacier indicates that this ice mass remained in the valley until at least 9700 ± 700 yr. The agreement between the two independent dating techniques (OSL and cosmogenic nuclide exposure age dating) increases our confidence in these age estimates. A date obtained from a boulder on a cirque moraine above the main valley indicates that glaciers advanced in cirques surrounding the icefield some time around 12,500 ± 900 yr. This evidence for an expanded North Patagonian Icefield between 10,900 ± 1000 yr and 9700 ± 700 yr implies cold climatic conditions dominated at this time.


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