After 9/11, two arborists joined the grim task of collecting evidence in the woods of Shanksville
The boulder which marks the general location of the impact site where the hijacked United Airlines Flight 93 plane crashed is pictured at the base of the hemlock grove at the Flight 93 National Memorial near Shanksville, in Stoystown, Pennsylvania, U.S., September 2, 2021. Picture taken September 2, 2021. REUTERS/Hannah Beier
