Morphometric analysis of solifluction lobes and rock glaciers in the Swiss Alps
Abstract Solifluction lobes and rock glaciers show similar geometry with a wide range of sizes. Morphometric analysis classifies these lobate landforms in the eastern Swiss Alps into five subgroups. A bouldery rock glacier has an active layer composed of matrix‐free boulders, whereas a pebbly rock g...
| Published in: | Permafrost and Periglacial Processes |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Wiley
2005
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1002/ppp.517 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fppp.517 https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.517 |
| Summary: | Abstract Solifluction lobes and rock glaciers show similar geometry with a wide range of sizes. Morphometric analysis classifies these lobate landforms in the eastern Swiss Alps into five subgroups. A bouldery rock glacier has an active layer composed of matrix‐free boulders, whereas a pebbly rock glacier consists of matrix‐supported debris derived from less resistant rocks. Both move by permafrost creep at 5–30 m depth, but the former tends to have a longer tread. A high solifluction lobe , having a riser 0.2–3 m high, originates mainly from annual gelifluction operating within the top 0.5 m of sediment, and its variation, a mudflow‐affected high solifluction lobe , occurs where prolonged snowmelt triggers a rapid flow of the thawed surficial layer. A low solifluction lobe has a riser up to 0.2 m high and occurs where thin fine‐grained debris responds mainly to diurnal frost creep. These lobes show, on the whole, positive relations between the tread length ( L ), width ( W ) and the riser height ( H ). However, a regression analysis separates the rock glaciers from the solifluction lobes by a distinct gap at W (or L )=30 m and H =3 m and provides different regression lines for the two populations. The morphometry primarily determined by the transport process is H , which approximates or slightly exceeds the maximum depth of movement. The depth of movement also affects the horizontal extent of a moving mass, which defines W . A lobe appears where horizontal homogeneity exceeds 3 H , and advances with time until reaching a maximum L controlled by climatic or dynamic conditions. Lobe morphometry can be used as an environmental indicator. Copyright © 2005 John Wiley & Sons, Ltd. |
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