Post-Younger Dryas warming collapsed ice sheets ~11,700 years ago, flooding coasts. Pre-Clovis sites survived inland — coastal evidence sits on ocean floor.
Key facts:
- During the last ice age ~20,000 years ago, sea level was roughly 400 feet lower and coastlines extended far further offshore
- The Aucilla River sinkhole where stone tools were found was dry land at that time, on a landscape now completely underwater
- The Younger Dryas (12,900–11,700 years ago) was a cold period that temporarily halted deglaciation; ice sheets collapsed after it ended, causing sea levels to rise and submerge any settlements built along coastlines
- All known pre-Clovis sites (San Diego, Pennsylvania, South Carolina, Texas, Florida) were inland sites that survived because they were above the waterline
- Coastal evidence from the ~117,000-year gap between the Cerutti Mastodon site (~130,000 BP) and the Clovis era (~13,000 BP) is now on the ocean floor, much of it unexplored
Sources
Younger Dryasen.wikipedia.orgThe Younger Dryas (YD, Greenland was the final climatic phase of the Last Glacial Period that occurred from around 12,900 to 11,700 years Before Present
The Younger Dryas impact hypothesis: a cosmic catastropheresearchgate.netIn this paper we review the evidence for the Younger Dryas impact hypothesis (YDIH), which proposes that at ∼12.9k cal a BP North America, South America, ...
The case of the Younger Dryas Impact Hypothesis - PMCpmc.ncbi.nlm.nih.govby JL Powell · 2022 · Cited by 49 — The hypothesis proposes that the airburst or impact of a comet ∼12,850 years ago caused the ensuing ∼1200-year-long Younger Dryas (YD) cool period
The Younger Dryas Impact: A Failed Hypothesisskepticalinquirer.orgby CR Chapman · Cited by 2 — The favored hypothesis is that YD cooling resulted from a reduction in the North Atlantic system of ocean currents (such as the Gulf Stream)
The Younger Dryas impact hypothesis: A requiemsciencedirect.comby N Pinter · 2011 · Cited by 179 — The Younger Dryas (YD) impact hypothesis is a recent theory that suggests that a cometary or meteoritic body or bodies hit and/or exploded over North America ...
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