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Abstract |
Rock slopes failures (RSF) are numerous in Iceland, especially in the eastern, northern and northwestern regions, which correspond to Tertiary basaltic formations. Five sites have been specifically studied in the Westfjords around Bolungarvík: Óshólar, Minni-Hlið, Sunddalur, Vatnadalur and Meira-Hraun. The aim is to obtain dating of RSF to better understand the chronosequence of post-glacial events. The use of Schmidt-hammer on RSF deposits, consisting in measuring the hardness of the deposited blocks, made it possible to establish relative dating between the different elements of the RSF, and to calibrate datings of the different RSF taking into account carbon-14 dates obtained onto and in the close vicinity of the same landforms, taking benefits of the landform superimposition. For this purpose, macroremains of Betula sp. and paleo-soils were sampled from pits dug in peaty depressions. The SHED results (Schmidt-hammer exposure age dating) thus date the oldest of Óshólar’s RSF to 11,000 cal BP, the Minni-Hlið’s RSF to 9,500 cal BP, that of Sunddalur at 8,700 cal BP, the Vatnadalur one to 8,200 cal BP and finally that of Meira-Hraun at 8,700 cal BP. The chronology of the RSFs dated to the beginning of the deglaciation or the first times of the Holocene therefore fits a paraglacial logic of the emplacement of these deposits. |
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