"HISTORICAL GEOLOGY" - A FREE, ONLINE TEXT FOR EARTH SYSTEM HISTORY SURVEY COURSES

We have written a free, online text“book” for undergraduate Historical Geology courses, available at https://opengeology.org/historicalgeology alongside three other OER geology texts. “Historical Geology” is Creative Commons licensed, so users can either read/assign as is, or rework content to their own specific needs. The text has numerous subdivisions, including 15 chapters on major themes in the discipline (rocks, stratigraphy, geologic time, plate tectonics, mass extinctions, paleoclimate, etc.) and 25 case studies reviewing particular places, events, taxa, or phenomena. The length and format of case studies vary–some are videos, while others are mainly graphical, or traditional text-based explorations. There are also 6 pages that we classify as “tools of the trade,” emphasizing skills such as mineral ID, reading geologic maps, and identifying and interpreting paleo-up indicators in sedimentary rocks. Finally, we feature 12 virtual field experiences (e.g., Siccar Point, the Massanutten Synclinorium, and Glacier National Park) and 14 virtual sample sets (e.g., igneous rocks, sediment samples, relative dating, and deformational structures). Each page is rich with interactive imagery, such as embedded virtual globes, 3D models, GIGAmacro and GigaPan images, Google Maps, image galleries, animated GIFs, and self-test quizzes. Feedback from students and adopting instructors is overwhelmingly positive, and they cite the interactive elements and free access as favorite features. None of the chapters is numbered; none is a prerequisite for any other. Instructors can mix and match to create a curriculum that matches their idiosyncrasies and needs. Pages are extensively interlinked and also include links to outside resources (For instance, vocabulary terms are linked to relevant Wikipedia pages). In 2022, we had 2900 to 3900 visitors per week to the site. We are currently revising the site for a 2nd edition and developing accompanying lab exercises.