Barbour gave his time free for the next 25 summers to manage field parties throughout the state, surveying the geological and paleontological resources of the State of Nebraska.[2] These trips were known as the Morrill Geological Expeditions, as they were funded by private donations from Charles Henry Morrill, regent of the University.[3] Their reports were published in the volumes of the Nebraska Geological Survey, as well as the Report of the State Geologist. The specimens that were found were added to the collections of the University museum.