From 1989 to 1992, the joint European Greenland Ice-core Project (GRIP) drilled through 3,029 metres (9,935 feet) of ice at Summit station in east-central Greenland before reaching bedrock.
Notes on verification
Multiple independent sources including the official GRIP final report, PANGAEA dataset, and peer-reviewed ESSD paper confirm the 1989-1992 timeframe and 3028.8 m depth at Summit, Greenland. Minor nuance: drilling stopped just short of true bedrock in silty basal ice, but this does not materially contradict the claim. [cascade flags: wikipedia_dropped_other_sources_exist | tier=unverified indep_score=0.3 clusters=4 claim_tier=notable] [rescored 2026-09-15: curated origin-host map (PR #65); unclassified hosts no longer scored as aggregators]
Sources
- Greenland Ice-core Project/Greenland Ice Sheet Project 2 | geochronology | Britannica (seed:history_and_archaeology)
- https://essd.copernicus.org/articles/15/3351/2023/ (corroboration)
- http://pratclif.com/climatechange/grip-final-report.htm (corroboration)
- https://doi.pangaea.de/10.1594/PANGAEA.55084 (corroboration)
- http://www.nerc-bas.ac.uk/icd/grip/griplist.html (corroboration)