Weathering Rind Age Assignment of Neoglacial Deposits in the Okstindan Mountains, Northern Norway

Abstract

AbstractPrevious soil stratigraphic analysis of soil morphogenesis in the Okstindan Mountains established a Late Neoglacial soil evolutionary sequence based on historically monitored and radio carbon-dated moraine positions over the last ~3.0 cal yr BP. Thus pedon evolution ranged from C/Cu→Ah/Cox/Cu→pedostratigraphic succession of Ah/C/Cu/Lb/ Cub/Ahb/Coxb/Cub pro files with a max i mum rind weathering time of ~1.0 kyr. Following successive re treat phases of Neoglacial ice, weathering rind development continued apace on moraines, each rind population recording weathering time fol lowing successive glacier still stands. The age of the youngest deposits falls within the period 1900-1910 AD, or the last 100 yrs, with variable moraine positions all documented by historical depictions of the position of the Austre Okstindan glacial lobe prior re treating to its present position. The next older group of deposits is considered to have been emplaced near the end of the LIA or around ~1800 AD, with time of rind development set at 200 yr, possibly older. The old est moraine set within the late Neoglacial sequence lies atop a pedostratigraphic column, the upper-most soil radio carbon dated at ~1.0 yr BP. Given the range of mean rind development across this thresh old of deposits, from 0.22 ±0.03 mm in the inner group, 0.66 ±0.07mm in the middle group, to 1.38 ±0.15 mm in the outer, older group, it is clear that finite measurements at several sites within a suite of deposits, some dated by radio carbon, can evenly discriminate be tween deposits in a glacial succession.