Eugster was active professionally attending conferences where he often delivered papers and lecturing at other universities or professional groups. The files in this series include correspondence regarding the event, material on travel arrangements, and often a copy of the paper or lecture presented. The paper presented, however, is not always in this series especially if it was later published. The files of published papers are in Series 5.

Slides were often the main part of Eugster's lectures, and this series includes many. Slides produced for a specific lecture are filed with other material concerning the lecture. There are, however, many slide files on general topics with no indication in which lecture they were used. These slides have been filed topically at the end of the series. The topics include: fossil syncline, geothermal brine, brine evolution, Great Salt Lake, closed basin, experimental petrology, supercritical fluids, PEIF, metamorphic sol., granite talk, sea water, oil-shale talk, and Magadi.

Information concerning travel arrangements for post-conference field trips are in this series.