Implications of present ground temperatures and relict stone stripes in the Ethiopian Highlands for the palaeoclimate of the tropics
Large sorted patterned grounds are the most prominent features of periglacial and permafrost environments of the mid and high latitudes, but have not yet been verified for the tropics. Here, we report on relict large sorted polygons (up to 8 m in diameter) and large sorted stone stripes (up to 1000...
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ftunivbern:oai:boris.unibe.ch:146117 2023-08-20T04:07:09+02:00 Implications of present ground temperatures and relict stone stripes in the Ethiopian Highlands for the palaeoclimate of the tropics Groos, Alexander R. Niederhauser, Janik Wraase, Luise Hänsel, Falk Nauss, Thomas Akçar, Naki Veit, Heinz 2020-06-29 application/pdf https://boris.unibe.ch/146117/1/esurf-2020-53-manuscript-version1.pdf https://boris.unibe.ch/146117/ eng eng Copernicus Publications https://boris.unibe.ch/146117/ info:eu-repo/semantics/openAccess Groos, Alexander R.; Niederhauser, Janik; Wraase, Luise; Hänsel, Falk; Nauss, Thomas; Akçar, Naki; Veit, Heinz (2020). Implications of present ground temperatures and relict stone stripes in the Ethiopian Highlands for the palaeoclimate of the tropics. Earth Surface Dynamics Discussions, pp. 1-37. Copernicus Publications 10.5194/esurf-2020-53 <http://dx.doi.org/10.5194/esurf-2020-53> 910 Geography & travel 550 Earth sciences & geology info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion NonPeerReviewed 2020 ftunivbern https://doi.org/10.5194/esurf-2020-53 2023-07-31T22:01:18Z Large sorted patterned grounds are the most prominent features of periglacial and permafrost environments of the mid and high latitudes, but have not yet been verified for the tropics. Here, we report on relict large sorted polygons (up to 8 m in diameter) and large sorted stone stripes (up to 1000 m long, 15 m wide, and 2 m deep) on the ~ 4000 m high Sanetti Plateau in the Bale Mountains, southern Ethiopian Highlands. For a systematic investigation of past and present frost-related processes and landforms in the Bale Mountains, we conducted geomorphological mapping both in the field and on satellite images. The sorted stone stripes were studied in more detail by applying aerial photogrammetry, ground-penetrating radar measurements, and 36Cl surface exposure dating. In addition, we installed 29 ground temperature data loggers between 3493 and 4377 m to analyse present frost occurrence and seasonal temperature variations from 2017 to 2020. Finally, we ran a simple experiment and combined recent ground temperature measurements with meteorological data in a statistical model to assess the air temperature depression needed for the past formation of deep seasonal frost and cyclic freezing and thawing on the plateau. Our results show that relict and modern periglacial landforms are common in the Bale Mountains. Nocturnal superficial ground frost on the plateau occurs at 35–90 days per year, but the mean annual ground temperature (~ 11 °C) is far off from seasonal or permanent frost conditions. The modelling experiment suggests a minimum air temperature depression on the plateau of 7.6 ± 1.3 °C for the emergence of several decimetre deep seasonal frost. The stone stripes probably formed under periglacial conditions in proximity of a palaeo ice cap on the plateau during the coldest period(s) of the last glacial cycle. We hypothesise that the slightly inclined and unglaciated areas of the plateau, the coexistence of regolith and large blocks, the occurrence of deep seasonal frost, as well as relatively dry conditions ... Article in Journal/Newspaper Ice Ice cap permafrost BORIS (Bern Open Repository and Information System, University of Bern) |
institution |
Open Polar |
collection |
BORIS (Bern Open Repository and Information System, University of Bern) |
op_collection_id |
ftunivbern |
language |
English |
topic |
910 Geography & travel 550 Earth sciences & geology |
spellingShingle |
910 Geography & travel 550 Earth sciences & geology Groos, Alexander R. Niederhauser, Janik Wraase, Luise Hänsel, Falk Nauss, Thomas Akçar, Naki Veit, Heinz Implications of present ground temperatures and relict stone stripes in the Ethiopian Highlands for the palaeoclimate of the tropics |
topic_facet |
910 Geography & travel 550 Earth sciences & geology |
description |
Large sorted patterned grounds are the most prominent features of periglacial and permafrost environments of the mid and high latitudes, but have not yet been verified for the tropics. Here, we report on relict large sorted polygons (up to 8 m in diameter) and large sorted stone stripes (up to 1000 m long, 15 m wide, and 2 m deep) on the ~ 4000 m high Sanetti Plateau in the Bale Mountains, southern Ethiopian Highlands. For a systematic investigation of past and present frost-related processes and landforms in the Bale Mountains, we conducted geomorphological mapping both in the field and on satellite images. The sorted stone stripes were studied in more detail by applying aerial photogrammetry, ground-penetrating radar measurements, and 36Cl surface exposure dating. In addition, we installed 29 ground temperature data loggers between 3493 and 4377 m to analyse present frost occurrence and seasonal temperature variations from 2017 to 2020. Finally, we ran a simple experiment and combined recent ground temperature measurements with meteorological data in a statistical model to assess the air temperature depression needed for the past formation of deep seasonal frost and cyclic freezing and thawing on the plateau. Our results show that relict and modern periglacial landforms are common in the Bale Mountains. Nocturnal superficial ground frost on the plateau occurs at 35–90 days per year, but the mean annual ground temperature (~ 11 °C) is far off from seasonal or permanent frost conditions. The modelling experiment suggests a minimum air temperature depression on the plateau of 7.6 ± 1.3 °C for the emergence of several decimetre deep seasonal frost. The stone stripes probably formed under periglacial conditions in proximity of a palaeo ice cap on the plateau during the coldest period(s) of the last glacial cycle. We hypothesise that the slightly inclined and unglaciated areas of the plateau, the coexistence of regolith and large blocks, the occurrence of deep seasonal frost, as well as relatively dry conditions ... |
format |
Article in Journal/Newspaper |
author |
Groos, Alexander R. Niederhauser, Janik Wraase, Luise Hänsel, Falk Nauss, Thomas Akçar, Naki Veit, Heinz |
author_facet |
Groos, Alexander R. Niederhauser, Janik Wraase, Luise Hänsel, Falk Nauss, Thomas Akçar, Naki Veit, Heinz |
author_sort |
Groos, Alexander R. |
title |
Implications of present ground temperatures and relict stone stripes in the Ethiopian Highlands for the palaeoclimate of the tropics |
title_short |
Implications of present ground temperatures and relict stone stripes in the Ethiopian Highlands for the palaeoclimate of the tropics |
title_full |
Implications of present ground temperatures and relict stone stripes in the Ethiopian Highlands for the palaeoclimate of the tropics |
title_fullStr |
Implications of present ground temperatures and relict stone stripes in the Ethiopian Highlands for the palaeoclimate of the tropics |
title_full_unstemmed |
Implications of present ground temperatures and relict stone stripes in the Ethiopian Highlands for the palaeoclimate of the tropics |
title_sort |
implications of present ground temperatures and relict stone stripes in the ethiopian highlands for the palaeoclimate of the tropics |
publisher |
Copernicus Publications |
publishDate |
2020 |
url |
https://boris.unibe.ch/146117/1/esurf-2020-53-manuscript-version1.pdf https://boris.unibe.ch/146117/ |
genre |
Ice Ice cap permafrost |
genre_facet |
Ice Ice cap permafrost |
op_source |
Groos, Alexander R.; Niederhauser, Janik; Wraase, Luise; Hänsel, Falk; Nauss, Thomas; Akçar, Naki; Veit, Heinz (2020). Implications of present ground temperatures and relict stone stripes in the Ethiopian Highlands for the palaeoclimate of the tropics. Earth Surface Dynamics Discussions, pp. 1-37. Copernicus Publications 10.5194/esurf-2020-53 <http://dx.doi.org/10.5194/esurf-2020-53> |
op_relation |
https://boris.unibe.ch/146117/ |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/esurf-2020-53 |
_version_ |
1774718611366084608 |