Thursday, July 27, 1871, from Albert Peale's journal: "This morning Elliott and I started for the Lower Falls with the intention of descending to the bottom of the cañon, a thing which all the hunters and trappers say cannot be done. . . we reached the bottom. . . . We took measurements with the aneroid barometer and found that the canyon was 1,000 feet deep where we descended." 
"The stream drops into a gorge with its already steeply inclined sides so covered with a thick growth of spruce, cedar, and alders that it was impossible to get an unobstructed view without going down to the very bottom of the gorge--a descent of some 200 feet. Rather than undertake to carry the dark box outfis down into the grove, I located it on the brink above. After placing the damp, sensitized plate in the plate holder it was backed with wet blotting paper and the holder itself wrapped in a wet towel--all these precautions being taken to preserve teh right degree of moisture up to the time of development. Then it was a quick descent through tangled brush and slide rock; selecting the point of view and making the exposure. The return trip was slower but more breath exhausting and I was in wringing perspiration by the time I was wrapped up in the dark box. With care a plate could be kept at least half an hour before development and at the same time be free from the blemishes due to a drying coating. Half a dozen such trips up and down made an arduous day's work." -- W. H. Jackson 
- "Thomas Moran," Smithsonian American Art Museum, accessed February 25, 2013, http://americanart.si.edu.
- Marlene Merrill, ed., Yellowstone and the Great West: Journals, Letters, and Images from the 1871 Hayden Expedition (Lincoln: University of Nebraska Press, 1999), 136.
- Yellowstone's Photo Collection, Yellowstone National Park Archives, Yellowstone National Park, accessed February 7, 2013, http://www.nps.gov/features/yell/slidefile/index.htm.
- Jackson, William Henry, 1843-1942. [Diaries of William Henry Jackson]. 1871, 1878. Yellowstone Research Center Archives.
- 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. #85.