We have measured an anomalous iridium concentration in the clays of the Cretaceous/Tertiary boundary in the Bidard section, thus confirming the planetary character of this anomaly. The iridium anomaly is synchronous with a very sharp minimum of the 13C/12C ratio and there is no evidence of any other iridium enrichment in marly concentrations away from the boundary. The integrated iridium content is of the same order of magnitude as that calculated from deep sea cores in the Pacific Ocean. In spite of a careful search, we have found no evidence of any exotic material.