Investigating Holocene mountain glaciations: a plea for the supremacy of glacial geomorphology when reconstructing glacier chronologies

Winkler, Stefan

doi:10.3112/erdkunde.2018.03.04

Cited by 10 publications

(8 citation statements)

References 26 publications

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“…T A B L E 1 Geomorphic disturbance intensity classification based on process magnitude and frequency following Eichel et al (2016) with indicative landforms/field observations. To assign a maximum terrain age to each plot, we used dated moraines in Mueller glacier foreland (Winkler, 2004(Winkler, , 2018, a glacier position map (Tscherrig, 1965; see Figure 1b), and aerial imagery in Turtmann glacier foreland.…”

Section: Vegetation and Environmental Plot Surveysmentioning

confidence: 99%

Similar vegetation‐geomorphic disturbance feedbacks shape unstable glacier forelands across mountain regions

et al. 2023

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Glacier forelands are among the most rapidly changing landscapes on Earth.Stable ground is rare as geomorphic processes move sediments across large areas of glacier forelands for decades to centuries following glacier retreat. Yet, most ecological studies sample exclusively on stable terrain to fulfill chronosequence criteria, thus missing potential feedbacks between geomorphic disturbances and vegetation colonization. By influencing vegetation and soil development, such vegetation-geomorphic disturbance feedbacks could be crucial to understand glacier foreland ecosystem development in a changing climate. We surveyed vegetation and environmental properties, including geomorphic disturbance intensities, in 105 plots located on both stable and unstable moraine terrain in two geomorphologically active glacier forelands in New Zealand and Switzerland. Our plot data showed that geomorphic disturbance intensities permanently changed from high/moderate to low/stable when vegetation reached cover values of around 40%. Around this cover value, species with response and effect traits adapted to geomorphic disturbances dominated.This suggests that such species can act as "biogeomorphic" ecosystem engineers that stabilize ground through positive feedback loops. Across floristic regions, biogeomorphic ecosystem engineer traits creating ground stabilization, such as mat growth and association with mycorrhiza, are remarkably similar. Nonmetric multidimensional scaling revealed a linked sequence of decreasing geomorphic disturbance intensities and changing species composition from pioneer to late successional species. We interpret this linked geomorphic disturbance-vegetation succession sequence as "biogeomorphic succession," a common successional pathway in unstable river and coastal ecosystems across the world. Soil and vegetation development were related to this sequence and only advanced once biogeomorphic ecosystem engineer species covered 40%-45% of a plot, indicating a crucial role of biogeomorphic ecosystem engineer stabilization. Different topoclimatic conditions could explain variance in biogeomorphic succession timescales and ecosystem engineer root traits between the glacier forelands. As glacier foreland ground is widely unstable, we

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Section: Vegetation and Environmental Plot Surveysmentioning

confidence: 99%

Similar vegetation‐geomorphic disturbance feedbacks shape unstable glacier forelands across mountain regions

et al. 2023

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“…Interpretation of exposure ages requires conformity with independent field evidence and the calculation of a mean age from all data may not be justified in all cases, as has been discussed in detail for moraine dating (cf. Ivy-Ochs et al 2007;Winkler 2018). The Bonaduz formation sediments, which overlie Tamins deposits, were deposited as a consequence of the Flims rock avalanche.…”

Section: Geomorphology and Age Of The Tamins Rock Avalanchementioning

confidence: 99%

The Tamins rock avalanche (eastern Switzerland): timing and emplacement processes

et al. 2022

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The Tamins rock avalanche lies adjacent to the Flims rock avalanche, the largest in the Alps. Its deposit forms a ridge across the Rhine Valley just downstream of the confluence of the Vorderrhein and Hinterrhein rivers. The deposit is dominated by a 1.6-km-long longitudinal ridge, Ils Aults, and two roughly 600-m-long transverse ridges. Several extensional scarps bear witness to spreading of the deposit. A breach through the deposit, where the Rhine River presently flows, reveals a carapace and intense fragmentation. Exposure dating using cosmogenic 36Cl yields an age of 9420 ± 880 years. This suggests that the Tamins event occurred in a time frame similar to the Flims event but was slightly earlier than the Flims rock avalanche, as also required by stratigraphic relationships. 3D volume modeling reveals bulking of only 14%. The motion of the rock avalanche seems to have occurred first as a flexible block, which underwent fragmentation and simple shearing where the top moved faster than the bottom. The ensuing spreading led to the formation of extensional scarps. There is no identified weak layer along the sliding surface; nevertheless, modeling suggests a friction angle of 10°.

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“…The establishment of such a chronological framework first requires detailed geomorphological investigations. This step is important, as careful geomorphological analyses are often overlooked when establishing glacier chronologies (Winkler, 2018). As high-resolution remote sensing data have hitherto not been used in this context, glacial landforms at key sites in the southern Black Forest were mapped by utilising these data and performing geomorphological field mapping.…”

Section: Introductionmentioning

confidence: 99%

Revisiting Late Pleistocene glacier dynamics north-west of the Feldberg, southern Black Forest, Germany

Hofmann

Rauscher

McCreary

et al. 2020

E&G Quaternary Sci. J.

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Abstract. The southern Black Forest was temporarily covered by a ∼1000 km2 large ice cap during the Late Pleistocene. However, during the last glaciation maximum in the Alps the atmospheric circulation over Europe was presumably characterised by the advection of humid air masses from the Mediterranean Sea. As a consequence, the ice cap of the Black Forest was likely in a leeward position due to its location north of the Alps. This raises the question of whether it reached its last maximum extent simultaneously with the glaciers in the Alps. As modern dating techniques have hitherto not been applied to the southern Black Forest, the timing of the last local glaciation maximum remains poorly constrained. As a first step towards an independent regional glacier chronology, we present a critical re-examination of glacial landforms in the area north-west of the highest summit of the Black Forest (Feldberg, 1493 m a.s.l.). It relies on both the analysis of remote sensing data and field mapping. The review of previous studies highlights important disagreements regarding the location of ice-marginal positions and their correlation. In addition, our findings challenge earlier studies on the glaciation of the Black Forest: some previously described ice-marginal positions could not be confirmed, whereas some of the newly identified moraines are described for the first time. This highlights the need for detailed geomorphological investigations prior to the application of geochronological methods. A multi-ridged series of terminal moraines in one of the studied valleys, Sankt Wilhelmer Tal, is proposed as the main target for future dating. Due to discrepancies with earlier studies, future efforts should reinvestigate other key areas related to the last glaciation of the southern Black Forest.

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Investigating Holocene mountain glaciations: a plea for the supremacy of glacial geomorphology when reconstructing glacier chronologies

Cited by 10 publications

References 26 publications

Similar vegetation‐geomorphic disturbance feedbacks shape unstable glacier forelands across mountain regions

Similar vegetation‐geomorphic disturbance feedbacks shape unstable glacier forelands across mountain regions

The Tamins rock avalanche (eastern Switzerland): timing and emplacement processes

Revisiting Late Pleistocene glacier dynamics north-west of the Feldberg, southern Black Forest, Germany

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