https://geodil.dperkins.org/h/898.html

The Geoscience Digital Image Library (GeoDIL) is a collection of Earth science images primarily intended as a teaching and learning resource for K-16 educators and students. This project was initiated at the University of North Dakota (UND) in fall 2000. Dexter Perkins and Joseph Hartman, of UND's Department of Geology and Geological Engineering, are the Library Directors. Most of the images in GeoDIL have been released into the public domain under a Creative Commons Zero dedication. A handful of images were produced by government employees and have always been in the Public Domain. All of these images have an icon detailing this at the bottom of their pages.