Earth sciences - reading
https://nerc.ukri.org/latest/publications/planetearth/
For maps, e.g. tectonic plates
http://www.worldatlas.com
http://ngm.nationalgeographic.com
Z.B.: http://science.nationalgeographic.com/science/earth/inside-the-earth/rocks-article/
Z.B.: http://science.nationalgeographic.com/science/earth/inside-the-earth/minerals-gems/
Z.B.: http://science.nationalgeographic.com/science/earth/the-dynamic-earth/plate-tectonics-article/
Z.B.: http://science.nationalgeographic.com/science/earth/the-dynamic-earth/weathering-erosion-article/
http://environment.nationalgeographic.com/environment/natural-disasters/earthquake-profile/
http://environment.nationalgeographic.com/environment/natural-disasters/volcano-profile/
https://quatr.us/geology (easy to medium)