MODERN GLACIATED

Modern Glaciated Valley Study

Table of Contents

Introduction3

Discussion3

Conclusion7

References9

Modern Glaciated Valley Study

Introduction

Krundalen, a valley occupied by three glaciers of the ice layer Jostedalsbreen, contains three groups of brown, two of which are out of date Neoglacial ('Little Ice Age ", LIA) limits. Exhibitions at the top of the brown outer display three sedimentary units. There is much dispute over when southern Norwegian glaciers attained their Neoglacial maximum. Traditionally, a 'Little Ice Age' glacier maximum has been assumed (Liestol, 2000: 45). This view was based largely on the well-established historical evidence for the mid-eighteenth century advance of Jostedalsbreen, combined with a lack of evidence for earlier Neoglacial advances. The existence of mature landscapes with well-developed soils beyond outermost moraine ridges, and an absence of evidence for older moraine ridges strengthened this conclusion. However, with the recognition in northern Scandinavia of an increasing number of pre 'Little Ice Age' glacier expansion episodes, some of which exceeded 'Little Ice Age' glacier limits (Karldn, 2003:48; 2006: 59; 2009: 65; 2001:88; Alexander and Worsley, 2003: 155; Griffey, 2006: 245; Worsley and Alexander, 2006a: 102; 2006b: 123; Griffey and Worsley, 2008: 166), the traditional view has increasingly come under scrutiny.

Discussion

Evidence from southern Norway for the age of the Neoglacial maximum is of six main types. First, there is the historical evidence referred to above. Although Worsley (2003: 139) pointed out that the historical evidence refers to glacier advances rather than to moraine age, there can be little doubt, particularly at Nigardsbreen (Figure 1), that the outermost moraines of several outlets of Jostedalsbreen date from the mid-eighteenth century (Karldn, 2001: 245; Matthews, 2002: 111; Grove, 2005: 85).

Second, lichenometric data from outermost moraines indicate that a much larger number of glaciers in Jotunheimen, Jostedalsbreen and Nordvestlandet (Figure 1) attained their Neoglacial maximum limits in the 'Little Ice Age', mostly at approximately the same time (Matthews and Shakesby, 2004: 147; Erikstad and Sollid, 2006: 56; Matthews, 2007a: 287). Along with the third type of evidence - Schmidt hammer 'R-values' - employed as a relative-age index (Matthews and Shakesby, 2004: 122; McCarroll, 2009a: 65, 2009b and in press), lichenometry has led to the recognition of a small number of pre-'Little Ice Age' Neoglacial moraines in eastern Jotunheimen. Such older moraines have been identified at only a very small minority of the glaciers examined, and there remains great uncertainty as to their age. The remaining types of evidence rely on stratigraphic approaches. The fourth and fifth types utilize distal sites characterized by glacio-fluvial and glacio-lacustrine sediments, respectively. In Bevringsdalen (west of Jostedals- breen) and at Blaisen (Hardangerjokulen) (Figure 1), stratigraphic evidence from alternating peat and glacio-fluvial sediments has permitted the recognition and dating of several Neoglacial expansion episodes that were smaller than the 'Little Ice Age' advances (Nesje and Dahl, 2001a: 104; 2001b: 155). At Vanndalsvatnet, the onset of glacio-lacustrine sedimentation indicates that Sporteggbteen (Figure 1) expanded after about 1400 BP (possibly as late as 500 BP). The age of the underlying non-glacial sediments shows that the glacier attained an appreciably greater ...