Geophysical Centre in Dourbes

We are particularly interested in loess sediments. Loess is a semi-consolidated material that consists mainly of fine sand, clay and carbonates and contains only a few magnetic minerals. The thickest loess deposits are found in China, where they are up to 180 metres thick and thus represent the last 2.58 million years.

Loess layers are mainly formed during glacial periods (dry, cold climate), and in a loess deposit they alternate with soil layers formed during interglacial periods (warm, humid climate). The geochemical processes during soil formation cause the uppermost loess layer to slowly transform into soil. Tiny, nanometre-sized magnetic minerals   are formed from the non-magnetic loess minerals. Soils formed on loess contain a variable proportion of newly formed magnetic minerals, which reflects the intensity of soil formation and in turn the development of the Earth's climate.