Les etages français et leur stratotypes: C. Cavelier and J. Roger (Editors), 1980. Me´moir No. 109. B.R.G.M., Orlea´ns, 295 pp., FF. 260.00. A collection of 44 articles, prepared under the auspices of the Comite´Français de Stratigraphie, defining and describing all stages and sub-stages as originally defined in France and now actually used in the international literature