In 2001, a previous IGN expedition carrying a gravimeter was stopped by weather at the Vallot shelter before reaching the summit of Mont Blanc.
Notes on verification
Verbatim confirmed in original IGN source; core fact independently corroborated by a separate outlet referencing the 2001 failed attempt, though the Vallot shelter detail specifically comes only from the primary source. [tier=silver indep_score=0.75 clusters=2 claim_tier=notable | kind=attributed eligibility=high (extractor: attributed/medium)]
Sources
- Une expédition pour mesurer la pesanteur sur le mont Blanc - Portail IGN - IGN (seed:geography_and_travel)
- https://ski-nordique.net/?cat=72348&id=6753180 (corroboration)
- https://www.msn.com/fr-fr/actualite/other/mesure-du-mont-blanc-2026-cest-parti/ar-AA2cfOQM (corroboration)