Abstract: In accordance with an illustrative embodiment of the present invention, a technique is provided for automatically processing measurements of the total natural gamma radioactivity and the thorium, uranium, potassium contents of formations surrounding a borehole to obtain a representation of the clay content of said formations in a zone of the borehole where the presence of one of said elements, called a disturbing element, is not related to clay. First, reference values of the total radioactivity and the thorium, uranium, potassium contents in the zone are determined. Then, at least two of these measurements are combined in accordance with a function determined from the reference values to produce a representation of the clay content of the formations corrected for the effect of the disturbing element.