Trapezoidal light in pine forest in 1981

Summary

In September 1981, near Pontvallain, four people observed a very intense trapezoidal light in a pine forest. The phenomenon lasted about 10 minutes and disappeared suddenly without making any noise. The gendarmerie arrived at the location shortly after but found nothing. The next day, a circle of ferns all lying in the same direction was discovered, hinting at a possible explanation. However, it was later determined that the light was moonlight refracting through the trees and the ground marks were caused by a forestry machine. Despite investigations, the case remains classified as unexplained by the GEIPAN.