From Halopedia, the Halo wiki
The Ross-Ziegler Blip was a stratigraphic event on Earth and a number of other planets named for two Earth geologists who discovered it in 2332, dating back approximately 100,000 years ago during the Late Pleistocene, coinciding with the activation of the Halo Array by the Forerunners that wiped the galaxy of sentient life. Since such a massive simultaneous extinction event seemed logically impossible, especially with the unexplainable absence of any fossil evidence, the anomaly was eventually dismissed as evidence of spatial distortion until the discovery of the Array by the United Nations Space Command in 2552. Given these new discoveries, the Blip was re-explained to be the result of the sudden destruction of bio-mass and sentient life at the conclusion of the Forerunner-Flood war.
After further research was conducted by Doctor William Iqbal and his team in Kenya, the remains of what was thought to be the Librarian's Catalog was discovered seven meters down in the Ross-Ziegler Blip.
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