For measurements of the mean sortable silt size of the detrital faction, biogenic carbonates were dissolved using acetic acid (20 %) and the organic matter was removed using hydrogen peroxide (33%) at 85°C. The samples were sieved through a 63 μm mesh and mixed in Sodium hexametaphosphate solution (0,2 %) in an ultrasonic bath for 2 minutes before analysis. The measurement was made using a Beckman Coulter Counter Multisizer 3 with a 100µm aperture tube valid for the 2-63µm. Two runs were performed with a total of 500,000 to 600,000 particles passing through the aperture. The number of particles counted in the 10-63µm range exceeds 10,000 and the reproducibility between these replicates is of the order of 1.5 to 2%.