The papers published in the present Memoir were presented at the International Symposium on Triassic stratigraphy held in Lausanne from October 20 to 25, 1991.
This symposium was organized under the auspices of the Subcommission on Triassic Stratigraphy (STS, Chairman A.Baud). About 60 scientists attended the meeting: Angiolini, L., Balini, M., Baud, A., Belhadj, Z., Benchabla, M., Besse, J., Beutler, G., Braek, P., Brandner, R., Budurov, K., Carter, E. S., Ciarapica, G., Cirilli, S., Courel, L., Dagys, A. S., Dagys, A. A., De Graciansky, P.-C., Demathieu, G., De Zanche, V., Dobruskina, 1., Durand, M., Egorov, A., Frechengues, M., Furrer, H., Gaetani, M., Gazdzicki, A., Gianolla, P., Goczan, F., Gradinaru, E., Guex, J., Haas, J., Hagdom, H., Hirsch, F., Jacobshagen, V., Jadoul, F., Kolar-Jurkovsek, T., Kotlyar, G., Kovacs, S., Krystyn, L., Laghi, G., Lepper, J., Martini, R., Mastandrea, A., Mertmann, D., Mork, A., Nakazawa, K., Oravecz-Scheffer, A., Palfy, J., Posenato, R., Remane, J., Rettori, R., Rieber, H., Russo, F., Siblik, M., Sishkin, M. A., Sobolev, E. S., Sudar, M., Tiwari, R.S., Tozer, E.T., Trifonova, E., Van Veen, P. M., Vijaya, V., Virgili, C., Voros, A., Warrington, G., Weitschat, W., Zakharov, Y., Zamparelli, R., Zaninetti, L. Several scientists from the Eastern Countries and from India had the opportunity to attend the symposium thanks to a generous support from the Swiss Academy of Sciences and from the Swiss National Research Foundation.
The technical organization of the meeting was greatly eased by the Geological Museum of Lausanne (Mr E. Thibault), the University and the Institute of Geology (Mrs A.M. Magnenat and L. Dufresne). Several collaborators which are warmly acknowledged contributed to the preparation of the present Memoir:
Mr M.Jaboyedoff (lnstitute of Mineralogy, Lausanne) for redrawing most of the text­figures.
Mrs R. Cosca (lnstitute of Mineralogy, Lausanne) for improving the english text of several papers.
Mrs N. Ghazinouri (Geological Museum, Lausanne) for retyping all the original manuscripts which were submitted on hard copies or unusable floppies.
We thank the "Fondation Herbette" and the Publications Commission of the University of Lausanne for supporting the financial cost of this memoir.