Grain-Size Analysis of Loess Deposits of the Last Glacial Period, NW France

Sammanfattning: Loess is an unique record of the paleoclimate of the Quaternary. Because it is directly deposited from the atmosphere, it can be used as a proxy for wind speed and circulation patterns. It can also be directly dated using luminescence. The site of the loess being investigated for this paper is PrimelTrégastel (Brittany), which lies in north-western France of the shore to the English Channel. The English Channel may be one of the sources for loess of the last glaciation, the Wichselian, and is the reason for choosing Primel-Trégastel to investigate. It is the purpose of this paper to investigate the climate of the time the loess was formed at Primel-Trégastel using grain-size distribution analysis, as well as comparing its properties to other loess sites in north-western Europe. The results show that the loess of Primel-Trégastel is coarse and have a relatively high sand content. That may imply that the loess was deposited during cold and arid conditions by high wind speeds, and at that it may have had a relatively close source. The results also exhibit cycles in the coarseness of the grain-size, indicative of the climate varying between cold and relatively warmer, resulting in relatively higher and lower wind speeds respectively. The loess of Nantois and Pegwell Bay are also relatively coarse, and the loess of Pegwell Bay also have a high sand content. The loess of Nussloch was in comparison more unlike the one of Primel-Trégastel, possibly due to the lack of a local source of sand at Nussloch.