Évolution postglaciaire de la sédimentation éolienne au sommet de deux parois rocheuses du nord de la Gaspésie, Québec (Canada)
The analysis of two aeolian cliff-top deposits in northern Gaspésie (Québec, Canada) allowed us to trace its postglacial evolution in relation to concomitant environmental changes. The aeolian sediments come from the rock walls below. They are blown up on the summit plateau by the very powerful asce...
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| Format: | Article |
| Language: | English |
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Physio-Géo
2020-06-01
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| Series: | Physio-Géo |
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| Online Access: | https://journals.openedition.org/physio-geo/11507 |
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| Summary: | The analysis of two aeolian cliff-top deposits in northern Gaspésie (Québec, Canada) allowed us to trace its postglacial evolution in relation to concomitant environmental changes. The aeolian sediments come from the rock walls below. They are blown up on the summit plateau by the very powerful ascending air flows generated by storm winds. The deposits mainly consist of poorly sorted coarse sand with a significant amount of gravel, and contain clasts up to 193 mm in length, making it one of the coarsest aeolian deposits described to date. At the top of Mount Saint-Pierre (425 m), the onset of aeolian sedimentation coincides with the installation of the first postglacial vegetation around 13600 years ago (sediment trap). It continued with a relatively constant sedimentation rate of 0.1 mm/year up to 2300 cal. BP. After that date, the rate of sedimentation was multiplied by 10 under the combined effect of a forest fire and possibly an intensification of storm winds. At Grande-Vallée, wind sedimentation was controlled by relative sea level fluctuations that alternately flooded or exposed the rock face, thus varying the extent of the face exposed to wind action. |
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| ISSN: | 1958-573X |