Case file · Close encounter

Trans-en-Provence

A physical ground trace was studied by France's official GEPAN.

1981 CE · 43.50, 6.48 · status: unexplained

The account

Soil analysis found compression and heat effects on vegetation — one of the best-documented trace cases.

The researched reading

A real trace, examined by a state agency, beneath a few seconds of sighting by one man. The lab results are suggestive but contested, so the case splits between an ordinary trace, a hoax and a genuine unknown.

Explanation	Weight	Why
Genuinely anomalous	32%	GEPAN found compression, heating and chlorophyll loss in plants, and gendarmes sampled within a day; it is among the best-documented physical trace cases.
Something known, misidentified	15%	Sceptics argue the ring was tyre or vehicle marks (the witness used a cement mixer and a car on the terrace), reproduced in a later experiment, which would make the trace ordinary.
A hoax or fabrication	15%	Critics such as Éric Maillot noted inconsistencies and the witness’s earlier joking about a UFO; the analyses, especially Michel Bounias’s, were never independently replicated.
Undetermined	15%	The share the reading had given to fabrication on doubt rather than evidence: the record does not settle it either way.
A poorly understood natural phenomenon	8%	If the plant and soil changes are real, an unusual energetic natural event is conceivable.
Secret human technology	6%	A test device landing in a Provençal garden is improbable but not impossible.
Perception, memory or mind	5%	The sighting lasted seconds; perception errors are possible but do not create the trace.
A known natural phenomenon	4%	Natural ground or fungal processes do not explain a fresh ring seen right after a sighting.

Official position: France’s GEPAN (now GEIPAN) studied the trace and classed the case as unexplained.

How the account grew

A retired mason's 1981 report of a lead-coloured double-saucer landing in his garden was investigated by the gendarmerie and the French space agency's GEPAN, whose report of compressed, heated soil and damaged alfalfa made it a showcase case; skeptics later argued the marks were tyre skids from the building work.

Year	Who	Added
1981	Renato Nicolaï (Niccolaï)	On 8 January a craft like two inverted plates, lead-coloured, about 2.5 m across, lands with a slight whistle and leaves within 30–40 seconds; a neighbour alerts the gendarmes.
1981	Local gendarmerie brigade	Two concentric circles about 2.2 and 2.4 m across, with black striations 'similar to tyre skid marks'; an outside investigator's claim that all vegetation vanished is called inaccurate.
1983	GEPAN (CNES), with INRA biochemist Michel Bounias	Ground compressed by 4–5 tonnes and heated below 600 °C; alfalfa pigments reduced, perhaps by pulsed microwaves; 'an event of great magnitude' with no explanation found after two years. (dropped: The tyre-mark observation in the police report.)
1995	Michel Figuet, SERPAN	The earliest debunking: tyre marks used to lend weight to a single witness's account.
2007	Rossoni, Maillot and Déguillaume, Les ovnis du CNES; L'Express	Argue for a hoax, perhaps a cement mixer's skid, and quote the witness on TV calling it 'a tale'; the same year L'Express calls it famous for its exemplary scientific inquiry.

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Sources

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