What we are looking for [...] is an agent capable--simultaneously and almost instantaneously--of bringing about all of the following: -a global flood -wildfires across an area of 10 million km2 -6 months of icy darkness followed by more than 1,000 years of glacially cold weather -a stratum of soil across more than 50 million km2 dated to the Younger Dryas Boundary (YDB) and infused with a cocktail of nanodiamonds, high-temperature iron-rich spherules, glassy silica-rich spherules, meltglass, platinum, iridium, osmium, and other exotic materials -a mass extinction of megafauna Wolfbach and her coauthors are forthright in their conclusion: 'Multiple lines of ice-core evidence appear synchronous, and this synchroneity of multiple events makes the YD interval one of the most unusual climate episodes in the entire Quaternary record. ... A cosmic impact is the only known event capable of simultaneously producing the collective evidence.