A revised chronology of key Vatnajökull (Iceland) outlet glaciers during the Little Ice Age

Mckinzey, Krista M.; Orwin, John F.; Bradwell, Tom

doi:10.3189/172756405781812817

Cited by 14 publications

(20 citation statements)

References 31 publications

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“…Overall, there is good concordance between the spatial pattern of tephra data collected by McKinzey et al (2005) and the spatial pattern of surfaces with similar histories revealed by the U 2 clustering approach. This success suggests that the lichen size distributions present on moraine surfaces that were deposited during specific depositional periods do have a common lichen signature and that the U 2 clustering approach can identify these surfaces.…”

Section: Results and Interpretationsupporting

confidence: 66%

“…We use lichen size data previously collected by the first two authors from the complex, fragmented Little Ice Age moraine suites of two adjacent southeastern Icelandic glaciers, Skálafellsjökull and Heinabergsjökull (McKinzey et al 2004). A known history of ice-margin oscillations derived from tephra ages exists for this location, providing an independent means for testing the U 2 clustering results (McKinzey et al 2005).…”

Section: Watson's U 2 Statisticmentioning

confidence: 99%

“…The prime objective of the McKinzey et al (2004McKinzey et al ( , 2005) study was to date fluctuations of these two glaciers over the last c. 500 years, so encom-passing the whole of the 'Little Ice Age' variation (Grove 2001). Dates were obtained using a combination of age-gradient lichenometry and tephrochronology (see McKinzey et al (2004McKinzey et al ( , 2005 for a more detailed description). McKinzey et al (2005) were able to present a map for the two glaciers of the lichenometric maximum and minimum ages of the Little Ice Age (LIA) moraine surfaces, bracketed by tephra ages (Fig.…”

Section: Applicationmentioning

confidence: 99%

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Identifying moraine surfaces with similar histories using lichen size distributions and the u2 statistic, southeast iceland

Orwin

Mckinzey

Stephens

et al. 2008

Geografiska Annaler: Series A, Physical Geography

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Identifying moraine surfaces with similar histories using lichen size distributions and the U 2 statistic, southeast Iceland. Geogr. Ann., 90 A (2): 151-164.ABSTRACT. Moraine ridges are commonly used to identify past glacier ice margins and so infer glacier mass balance changes in response to climatic variability. However, differences in the form of past ice margins and post-depositional modification of moraine surfaces can complicate these geomorphic records. As a result, simple relationships, such as distance from current ice margin, or linear alignments, may not necessarily indicate moraines deposited contemporaneously. These disturbances can also modify the size distribution of lichen populations, providing a distinctive signature for surfaces with similar histories and a means of identifying contemporaneous moraine surfaces. In this paper, statistical analysis of lichen size distributions is used to identify moraine surfaces with similar histories from complex suites of Little Ice Age moraine fragments in the proglacial areas of Skálafellsjökull (including Sultartungnajökull) and Heinabergsjökull, southeast Iceland. The analysis is based on a novel use of the goodness-of-fit statistic, Watson's U 2 , which provides a measure of 'closeness' between two sample distributions. Moraine fragments with similar histories are identified using cluster analysis of the U 2 closeness values. The spatial pattern of the clustered moraines suggests three distinct phases of moraine deposition at Skálafellsjökull and Heinabergsjökull, four phases at Sultartungnajökull and a digitate planform margin at Heinabergsjökull. These spatial patterns are corroborated with tephrochronology. The success of the U 2 statistical analysis in identifying surfaces with similar histories using lichen size distributions suggests that the technique may be useful in augmenting lichenometric surface dating as well as differentiating between other surfaces that support lichen populations, such as rock avalanche deposits.

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Section: Results and Interpretationsupporting

confidence: 66%

Section: Watson's U 2 Statisticmentioning

confidence: 99%

Section: Applicationmentioning

confidence: 99%

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Identifying moraine surfaces with similar histories using lichen size distributions and the u2 statistic, southeast iceland

Orwin

Mckinzey

Stephens

et al. 2008

Geografiska Annaler: Series A, Physical Geography

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“…The age-size approach adopted by Evans et al (1999), together with their acceptance of historical documentation of an 1887 AD maximum age for the outermost Little Ice Age moraine and associated glacial lake shorelines (Thorarinsson 1939), yields a post 1887 AD recession pattern, during which the proglacial outwash migrated from an unconfined easterly flowing incised fan to a southerly draining, topographically confined and terraced, linear sandur that was channelled between the receding glacier snouts and their long-term outwash heads (Figure 3). The use of the size-frequency method, together with the employment of tephras recovered from the outermost moraines on the foreland, prompted McKinzey et al (2004McKinzey et al ( , 2005 to propose a longer chronology in which the Little Ice Age limit appears to date to either 1850 -1887 AD, Figure 2. Aerial photograph extracts (Landmaelingar Islands) from 1947, 1957, 1969and 1989, showing the extent of glacier ice in each year and the sequential development of the proglacial landforms.…”

Section: Historical Evolution Of Heinabergsjökull and Skalafellsjökullmentioning

confidence: 99%

Heinabergsjökull and Skalafellsjökull, Iceland: active temperate piedmont lobe and outwash head glacial landsystem

Evans

Orton

2014

Journal of Maps

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A 1:15,000 scale map of the glacial geomorphology and surficial geology of the Heinabergsjökull and Skalafellsjökull glacier forelands in southeast Iceland depicts a landsystem imprint of actively receding temperate glaciers in a mountain terrain with a high glacifluvial sediment yield. The landsystem is characterised by the three diagnostic depositional domains for active temperate glacier systems (marginal morainic; subglacial; glacifluvial/glacilacustrine) together with site-specific landform-sediment assemblages indicative of jökulhlaup drainage from ice-dammed lakes. Other features are overridden moraines and fluted kame terraces, indicative of ice-marginal and glacifluvial palimpsests preserved beneath temperate glacier ice. A significant outwash head in front of Heinabergsjökull records the long-term accumulation of proglacial outwash and was responsible for a radical change in proglacial drainage patterns (topographically unrestricted to restricted) once the glacier snout had receded from the ice-contact face of the landform. The Heinabergsjökull/ Skalafellsjökull foreland constitutes a modern analogue for active temperate piedmont lobes associated with the construction of large outwash heads fed by high glacifluvial sediment yields. This is one of the most common glacial depositional scenarios associated with the more restricted, mountain-based, average glaciation style during a typical cold stage.

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“…Temperatures continued to decrease during the Little Ice Age, which reached its maximum in Iceland around 1800 AD (e.g. McKinzey et al 2005; Bradwell et al 2006). Studies of Icelandic outlet glaciers (Thórarinsson 1943; Björnsson 1979) indicate that although their extent fluctuated somewhat, on average glacier volumes did not change significantly between 1750 and 1890.…”

Section: Glacial Isostatic Adjustmentmentioning

confidence: 99%

Glacial rebound and plate spreading: results from the first countrywide GPS observations in Iceland

Árnadóttir¹,

Lund

Jiang³

et al. 2009

Geophysical Journal International

133

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S U M M A R YIceland is one of the few places on Earth where a divergent plate boundary can be observed on land. Direct observations of crustal deformation for the whole country are available for the first time from nationwide Global Positioning System (GPS) campaigns in 1993 and 2004. The plate spreading across the island is imaged by the horizontal velocity field and high uplift rates (≥10 mm yr −1 ) are observed over a large part of central and southeastern Iceland. Several earthquakes, volcanic intrusions and eruptions occurred during the time spanned by the measurements, causing local disturbances of the deformation field. After correcting for the largest earthquakes during the observation period, we calculate the strain rate field and find that the main feature of the field is the extension across the rift zones, subparallel to the direction of plate motion. Kinematic models of the horizontal plate spreading signal indicate a slightly elevated rate of spreading in the Northern Volcanic Zone (NVZ) (23 ± 2 mm yr −1 ), while the rates at the other plate boundary segments agree fairly well with the predicted rate of plate spreading (∼20 mm yr −1 ) across Iceland. The horizontal ISNET velocities across north Iceland therefore indicate that the excessive spreading rate (>30 mm yr −1 ) observed by GPS in 1987-1992 following the 1975-1984 Krafla rifting episode was significantly slower during 1993-2004. We model the vertical velocities using glacial isostatic adjustment (GIA) due to the recent thinning of the largest glaciers in Iceland. A layered earth model with a 10-km thick elastic layer, underlain by a 30-km thick viscoelastic layer with viscosity 1 × 10 20 Pa s, over a half-space with viscosity ∼1 × 10 19 Pa s can explain the broad area of uplift in central and southeastern Iceland. A wide area of significant residual uplift (up to 8 mm yr −1 ) is evident in north Iceland after we subtract the rebound signal from the observed rates, whereas the Reykjanes Peninsula and the Western Volcanic Zone (WVZ) appear to be subsiding at a rate of 4-8 mm yr −1 . We observe a coherent pattern of small but significant residual horizontal motion (up to 3 mm yr −1 ) away from Vatnajökull and the smaller glaciers that is most likely caused by glacial rebound. Our study demonstrates that the velocity field over a large part of Iceland is affected by deglaciation and that this effect needs to be considered when interpreting deformation data to monitor subglacial volcanoes in Iceland.

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A revised chronology of key Vatnajökull (Iceland) outlet glaciers during the Little Ice Age

Cited by 14 publications

References 31 publications

Identifying moraine surfaces with similar histories using lichen size distributions and the u2 statistic, southeast iceland

Identifying moraine surfaces with similar histories using lichen size distributions and the u2 statistic, southeast iceland

Heinabergsjökull and Skalafellsjökull, Iceland: active temperate piedmont lobe and outwash head glacial landsystem

Glacial rebound and plate spreading: results from the first countrywide GPS observations in Iceland

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