Ancient ice trapped within an ice cap in Northwestern Tibet appears to preserve fragments from the last ice age, extending Earth’s glacial record by over 100,000 years and making them the oldest ice cores ever recovered from the region, according to a new study.

The analysis, comparing ice cores drilled from the Guliya Plateau in 1992 and 2015, shows that both samples contained similar oxygen isotope patterns, suggesting that the environmental signals they contain are consistent and reproducible.