Samples taken in February and October 2010. Analysis performed at the Institute of Earth Sciences, University of Lausanne, Swizerland, on an ARL Thermo X'tra diffractometer. The intensities of the identified minerals are measured for a semi-quantitative estimate of the proportion of clay minerals, which is therefore given in relative percent without correction factors for both fractions, following the procedures of Kübler (1987) and Adatte et al. (1996).