G. N. Allen, 1812-1877
"Another of [Hayden's] selections was the other diarist, George Allen, who had been Hayden's professor of geology at Oberlin College back in the late 1840s. Hayden had a very personal interest in both Peale and Allen and it is because of this interest that the two men provide such close personal looks at Hayden in their diaries." 
"Prof. G. N. Allen acted as botanist with great success, as far as Fort Ellis, and was assisted by Robert Adams. After Prof. Allen's departure, Mr. Adams took charge of the botanical collections." --F. V. Hayden 
"George Allen was a gentle and unassuming professor. Although highly competent he was not distinguished in his field, and certainly he was without powerful political influence. Wanting to see the Rockies and to work with Hayden, Allen had two strikes against him: his age 9he was 58 in 1871) and his lack of prolonged, physically demanding fieldwork. Hayden gave him every assurance that 'younger members of my party [will] gladly take upon themselves. . . whatever hardships there are, as standing guard at night, etc.' In April, Hayden assigned Allen the job of mineralogist and geologist, writing that 'there will be no one along but you and myself who make any pretensions to a knowledge of these subjects.'" 
- Merrill, Marlene. With Hayden in the Field : a Case Study Based on Unpublished Letters and Diaries from the 1871 Yellowstone Survey. 1993. Yellowstone Research Center Archives.
- Robert Samuel Fletcher, A History of Oberlin College from Its Foundation through the Civil War, (Oberlin, O.: Oberlin College, 1943).
- F. V. Hayden, Preliminary Report of The United States Geological Survey of Montana and Portions of Adjacent Territories; Being A Fifth Annual Report of Progress (Washington: Government Printing Office, 1872), pg. 4.