Researchers found glass spherules in sediment from Yvonne Malinowski's backyard in Melrose, Pennsylvania, containing flecks of pure iron indicating formation at temperatures above 2,000°C (about 3,600°F).
Notes on verification
Confirmed by original National Geographic reporting and cross-checked against the peer-reviewed PNAS study (Wittke et al., 2013), which independently documents the same site, spherule composition, and high-temperature formation mineralogy. The specific factual detail is well corroborated, though the broader Younger Dryas impact hypothesis remains scientifically debated.
Sources
- Did a Comet Really Kill the Mammoths 12,900 Years Ago? (nationalgeographic.com)
- https://www.pnas.org/doi/10.1073/pnas.1304059110 (pnas.org)
- https://pmc.ncbi.nlm.nih.gov/articles/PMC3780899/ (pmc.ncbi.nlm.nih.gov)