non-free are here ...
Introduction to Physical Geology by Shulman.
Fundamentals of Geology by Schulte.
Introduction to Earth Science, 2nd edition (from Virginia Tech) by Neser.
An Introduction to Geology, by Johnson, Affolter, Inkenbrandt, and Mosher.
Metamorphic rocks lineation and foliation.
Physical Geology "H5P" edition by Panchuk.
Based on Physical Geology, 2nd ed by Earle.
The Story of Earth - An Observational Guide.
Homepage of Dexter Perkins with links. But also linked below ↓.
Opticalmin - an image library of minerals in thin section.
GeoDIL - a library of geological photos.
Rocks and Minerals - a library of hundreds of 3-d rotatable and scalable models of fossils, rocks and minerals.
Geological Structures - A Practical Introduction by Waldron and Snyder.
Samizdat Press at Colorado School of Mines. Geophysics books.
Some google drive out there has a lot of books/references: Geology Textbooks - Google Drive. I don't know the origin of it, but it's there.