Geology is the study of the earth and its life, especially by looking at rocks. It might seem an unusual subject for a girl in 1894, but remember that Lou Henry had always loved the outdoors because of her father's love of nature.

She never had a regular paying job as a geologist after her graduation from Stanford University, but geology continued to be a passion throughout her life. During all of her travels, she gathered geological samples from many countries and sent them back to California. This collection became one of the most complete of any university. What would Lou Henry Hoover have thought about the Sojourner's trip to the surface of Mars about a hundred years after her graduation from Stanford?

Lou Henry Hoover also helped her husband translate an old book about mining and metals from Latin to English. The book, De Re Metallica, took them several years to complete and was received with great interest by geologists, colleges, and libraries.