The April 1971 edition of the Geological Society of Minnesota (GSM) newsletter included an updated map of the location of bronze geologic markers, an article on how agates form, and a story on the early history of society.
Map showing locations of bedrock outcrops (rock exposed at the land surface), scale 1:125,000. Electronic file available at: ftp://mgsftp2.mngs.umn.edu/map_catalog/pdf/umn22390.pdf
Students study the Mississippi River's riverbed. View of six men and women, wearing casual attire, standing and kneeling on the banks of the Mississippi River.