Slope hummock development, Fosheim Peninsula, Ellesmere Island, Nunavut, Canada
Abstract Slope hummocks, a type of nonsorted patterned ground, are composed of stratified, organic, silty sand, and develop through the interaction of niveo-eolian deposition, solifluction, slopewash, and vegetation growth. Fields of hummocks show consistent patterns: forms on convex slopes increase...
| Published in: | Quaternary Research |
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| Format: | Article in Journal/Newspaper |
| Language: | English |
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Cambridge University Press (CUP)
2011
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| Online Access: | http://dx.doi.org/10.1016/j.yqres.2010.12.013 http://api.elsevier.com/content/article/PII:S0033589410001572?httpAccept=text/xml http://api.elsevier.com/content/article/PII:S0033589410001572?httpAccept=text/plain https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589400007158 |
| Summary: | Abstract Slope hummocks, a type of nonsorted patterned ground, are composed of stratified, organic, silty sand, and develop through the interaction of niveo-eolian deposition, solifluction, slopewash, and vegetation growth. Fields of hummocks show consistent patterns: forms on convex slopes increase in height downslope until the channel is reached, whereas those on convexo-concave slopes increase on the upper convexity but are buried by niveo-eolian deposition downslope of the snowbank remnant. These trends can be reproduced using a simple numerical model based on measured slope and snow depth profiles, sediment concentrations in the snow and solifluction rates. The model indicates that hummocks transit slopes of 20–40 m in about 2–4 ka, a time-frame that is plausible given site emergence, measured rates of solifluction, and published dates for organic horizons within hummocks on northern Ellesmere Island. Sensitivity analyses show that long-term effect of climate warming on hummock heights may differ depending on whether it is accompanied by precipitation increase or decrease. The required combination of two-sided freezing to promote plug-like movement, incomplete vegetation cover and thin snow that enable eolian erosion during winter and spring, and vegetation growth in snow-bed sites to stabilize niveo-eolian deposits may explain why these forms are important regionally but apparently are not present throughout the Arctic. |
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