In the 1800's! Here is Hayden Pass' namesake, Ferdinand Vanderveer Hayden, sitting there in the flesh! Here's the description from
http://www.huh.harvard.edu/libraries/fieldwork_exhibit/photographs/photographs.htm
"July 1877 Pictures of the United States Geological Survey of the Territories under the direction of Ferdinand Vanderveer Hayden [1829-1887]. Photograph taken by William Henry Jackson [1843-1942] at La Veta Pass, Colorado.
"Three stragglers" in background and from left to right (mostly seated): Sir Joseph Dalton Hooker [1817-1911], Asa Gray [1810-1888], Mrs. Strachey, Jane Loring Gray [1821-1909], Captain Stevenson, Dr. Lanborn, General Strachey, Ferdinand Vanderveer Hayden [1829-1887]
From the archives of the Gray Herbarium
^..^ Julie