These days, the questions I'm asked most often about the Glossary of Geology are when the fourth edition will be available and how it differs from the third. The new Glossary should be at the printer by the time you read this and available in a few weeks. It contains more than 3,000 new terms, and nearly 9,000 of the definitions from the old edition have been updated. The 1997 edition contains just over 37,000 terms; it is about 100 pages longer than the 1987 edition.
The practice, technology, and terminology of the earth sciences have changed a lot in 10 years. Geoscientists use geographic information systems (GIS) and global positioning systems (GPS) as well as new tools and techniques for analysis, modeling, exploration, and communication. Words from GIS, GPS, sequence stratigraphy, and environmental geophysics are some of the new terms in this edition. Updated definitions reflect changes in meaning and in scientific thought. The concept of geosynclines, for example, has lost favor and much of that terminology is considered to be obsolete. The new edition retains terms of historical significance, however, with modified definitions.
To see changes in usage–what's "in" and what's "out"–has been interesting. "Event" is "in" in several disciplines. Nonetheless, eruption event, snow event, flood event, storm event, and rain event did not make it into the new edition. Some of the terms that have slipped "out" in the past decade are listed below. The "in" column gives their favored replacements, at least in the context of certain definitions.
| OUT | IN |
| algal | microbial |
| biologic | biogenic |
| fossil fragment | bioclast |
| micron | micrometer |
| oolith | ooid |
| pellet | pelloid |
| zone of aeration | aeration zone |
| zone of saturation | saturated zone |
To produce the new edition, the American Geological Institute followed the process used for earlier editions. Experts from various geoscience disciplines reviewed and updated sets of terms and definitions from the Glossary. They also proposed candidate terms and definitions to be added. Other sources of new terms included AGI's GeoRef database and contributions from Glossary users. My role has been to work with the reviewers, edit their contributions, and manage the revision.
Just as new technologies have affected the practice of geology, they have affected the process of revising the Glossary. E-mail has been such a help and time saver that I wonder how I managed earlier revisions without it. My favorite example of quick turnaround occurred when I e-mailed a question about meteorites to a scientist whose address was in Ohio. He e-mailed the answer a few hours later from his field site in Antarctica. Using the computer to identify and correct problems and inconsistencies in the data has been another time saver. It helped me quickly identify the "see" references that led nowhere. The computer also found all the microns and changed them to micrometers in a flash. The fourth edition of the Glossary is the first to be typeset at AGI. Ventura Publisher met my need for flexibility in proof formats. Having special characters and superscripts and subscripts appear in printouts as they should instead of as mnemonics simplified editing and proofreading.
As with earlier editions, the accuracy and authority of the Glossary of Geology comes from the scholarship and expertise of the reviewers. More than 100 helped with this revision. It speaks well for the earth sciences that so many outstanding geoscientists willingly make time as volunteers to work on each new edition. They, like former Glossary editor Robert L. Bates, have been committed to maintaining the quality of the Glossary of Geology. Bob and I began planning for the new edition three years ago–just a few months before his death. It is fitting that AGI has dedicated the fourth edition to him.