Consists of references to geologic field trip guidebooks of North America. Most of the guidebooks cited are from the period 1940-1988. A few are from earlier years. Geoscience Information Society (GSIS) volunteers have added many post-1988 guidebooks to the database. Beginning in 2002, new guidebooks will be added to GeoRef as part of the regular database production, and then added to the guidebook database from the GeoRef records.