The 16 reports that make up this volume constitute the final report of Project 203 of the International Geological Correlation Programme, which dealt with Permo-Triassic events of the East Tethys and their intercontinental correlation. During the five-year life of Project 203, participants met twice in Beijing, and once each in Columbus, Ohio (USA) and Brescia (Italy), to exchange views, consider new data, and examine pertinent sections in the field. These conferences have provided new insight into the stratigraphy, classification, and relations of strata within the Permo-Triassic boundary interval, and a wider appreciation of the problems involved in the correlation and interpretation of these rocks, which document an unusually significant period in Earth history.

It will be clear to the reader that the 40 contributors to this volume are in substantial agreement in their interpretation of many features of the Permo-Triassic boundary interval, but disagree, at least by implication, in their evaluation of others. Although as editors we have strived to achieve readability and uniformity in basic terminology, we have also attempted to avoid interference with strongly held individual views, even though they run contrary to those of other contributors. In brief, it would be inappropriate to suggest that in five short years participants in Project 203 solved all problems with respect to the Permo-Triassic boundary interval – for many of these are likely to persist as long as vigorous study continues. We do suggest, however, that data and ideas gathered and expressed during the five-year life of Project 203 and summarized in this volume are important contributions toward understanding and interpreting the rock and fossil record of the late Permian and early Triassic.