First and second annual report of progress by the state geologist and the assistant and chemist on the Geological survey of the state of Iowa, together with the substance of popular letters contributed to the newspapers of the state during the years 1866 and 1867, in accordance with law; also extracts originally contributed to scientific journals as a part of the work of the survey
Iowa Geological Survey; White, Charles A. (Charles Abiathar), 1826-1910; Hinrichs, Gustavus Detlef, 1836-1923; St. John, Orestes Henry