Soil sample from flying saucer depression — Wright-Patterson AFB (Project SIGN), September 1948
On September 9, 1948, Project SIGN at Wright-Patterson AFB submitted a soil sample to the FBI Laboratory for analysis. The sample was taken from a depression approximately 2 ft in diameter and 1 ft thick, allegedly made by a flying saucer that settled gently and then rebounded to approximately 20 ft altitude. The FBI Laboratory was asked to test for unusual elements, heat effects, and radioactivity. No comparison soil sample from the surrounding area was included.
“Project 'SIGN' soil sample: depression approximately 2 ft diameter, 1 ft thick, made by object that 'settled gently, rebounded to 20 ft'; submitted to FBI Lab for analysis for unusual elements, heat, and radioactivity.”
Physical evidence case. FBI Lab analysis results appear in Section 4 (soil determined to be ordinary sand). No geographic location of the original depression is provided in the available text. The same incident appears in Section 4 with additional detail including the FBI Lab response.