The following is from a mirrored web of CUFOS:
Renato Nicolai, a 52-year-old technician, was working on an upper-level terraced portion of his property at about 5:00 p.m. when he heard a whistling sound to the east. Turning, he observed an object resembling "a somewhat bulging disk like two plates glued to each other by the rim, with a central ring some 20 cm [8 inches] wide." The disc passed over two trees adjacent to his garden, descended and landed about 50 meters away.
After a few seconds on the ground, the object ascended, kicking up some dust, and retraced its incoming flight path, once again emitting a low whistle, and disappeared in the east. As it flew away, Nicolai saw two round protrusions on the underside like landing gear, and two circular areas that looked like "trap doors." The total elapsed time was 30-40 seconds.
Nicolai went to inspect the landing site, and found a circle about two meters in diameter with tracks or traces at certain spots on the circumference of the circle. Investigators described finding two concentric circles about 10 cm wide, one 2.2 meters in diameter and the other 2.4 meters in diameter.
Next day, the Gendarmerie arrived at the scene and gathered samples of the traces and control samples from outside the traces. Ultimately, GEPAN (Groupe d'Etude des Phenomenes Aerospatiaux Non-Identifies)--a unit of the French space agency organized to investigate UFO reports--was called in by the Gendarmerie, and 39 days after the landing they examined the site, collecting soil and vegetation samples for analysis. Their investigation also encompassed an appraisal of the witness, a check of atmospheric conditions at the time of the UFO encounter, and air traffic on the day in question. GEPAN, in conjunction with the Gendarmerie, continued their investigation over the course of the next two years.
The GEPAN final report, entitled Technical Note 16, came to the following conclusions:
1. Evidence indicates a strong mechanical pressure, probably due to a heavy weight, on the ground surface.
2. At the same time or immediately after this pressure, the soil was heated up to between 300 and 600 degrees C.
3. Trace quantities were found of phosphate and zinc.
4. The chlorophyll content of the wild alfalfa leaves in the immediate vicinity of the ground traces was reduced 30% to 50%, inversely proportional to distance.
5. Young alfalfa leaves experienced the highest loss of chlorophyll, and moreover exhibited "signs of premature senescence."
6. Biochemical analysis showed numerous differences between vegetation samples obtained close to the site and those more distant.
7. "It was possible to qualitatively show the occurrence of an important event which brought with it deformations of the terrain caused by mass, mechanics, a heating effect, and perhaps certain transformations and deposits of trace minerals."
8. Nuclear irradiation does not seem to account for the observed effects, but some type of electrical energy field might account for the chlorophyll reductions.
No single case is likely to provide absolute proof. Although some French researchers have criticized the methodology used at Trans-en-Provence, the case remains provocative and contains strong evidence suggestive of a real, unexplained, physical event.
(GEPAN, Note Technique No. 16, Enquete 81/01, Analyse d'une Trace; March 1, 1983; Jean-Jacques Velasco, MUFON 1987 International UFO Symposium Proceedings, Seguin, Texas, 1987, pp. 51-67; Jerome Clark, The UFO Encyclopedia, Detroit, Apogee Books, 1990, pp. 205-207; Eric Maillot and Jacques Scornaux, in Hilary Evans and Dennis Stacy, UFOs: 1947-1997: Fifty Years of Flying Saucers, London, England, John Brown Publishing, 1997, pp. 151-159.)