1. A method of predicting the facies of a geological formation traversed by a borehole comprising: (a) moving a sonde through a plurality of predetermined levels in a borehole traversing a geological formation and recording the log measurements taken by the sonde at each of the predetermined levels; (b) selecting the recorded log measurements which are stable over consecutive levels; (c) assigning the selected log measurements to points in an n dimensional space in which n is equal to the number of log measurements recorded at each of the levels; (d) selecting pairs of modes which are furthest apart from each other in the n dimensional space, each of the modes corresponding to a point of maximum density of the points in the n dimensional space; (e) assigning each point in the n dimensional space to the respective closest mode, thereby defining classes of log measurements, each class characterizing an electro-facie; (f) correlating the electro-facies with the facies traversed by the borehole; and (g) comparing a recorded log measurement not selected in step (b) to the classes of log measurements to predict the facie of the geological formation traversed by the borehole associated with the level of the log measurement not selected in step (b).