A large rounded granitic glacial erratic from the Iowa State College campus has several granitic dikes up to a few inches in width crisscrossing it. They project from the surface of the dike as much as three inches and have smooth surfaces. The surface of the granite country rock is pitted but quite sound. It is believed probably that the boulder has been etched by wind action.
Proceedings of the Iowa Academy of Science
©1941 Iowa Academy of Science, Inc.
Gwynne, C. S.
"Etched Boulder at Ames, Iowa (Abstract),"
Proceedings of the Iowa Academy of Science, 48(1), 296-296.
Available at: https://scholarworks.uni.edu/pias/vol48/iss1/70