An independent evaluation of the Younger Dryas extraterrestrial impact hypothesis.
نویسندگان
چکیده
Based on elevated concentrations of a set of "impact markers" at the onset of the Younger Dryas stadial from sedimentary contexts across North America, Firestone, Kennett, West, and others have argued that 12.9 ka the Earth experienced an impact by an extraterrestrial body, an event that had devastating ecological consequences for humans, plants, and animals in the New World [Firestone RB, et al. (2007) Proc. Natl. Acad. Sci. USA 104:16016-16021]. Herein, we report the results of an independent analysis of magnetic minerals and microspherules from seven sites of similar age, including two examined by Firestone et al. We were unable to reproduce any results of the Firestone et al. study and find no support for Younger Dryas extraterrestrial impact.
منابع مشابه
Chronological evidence fails to support claim of an isochronous widespread layer of cosmic impact indicators dated to 12,800 years ago.
According to the Younger Dryas Impact Hypothesis (YDIH), ∼ 12,800 calendar years before present, North America experienced an extraterrestrial impact that triggered the Younger Dryas and devastated human populations and biotic communities on this continent and elsewhere. This supposed event is reportedly marked by multiple impact indicators, but critics have challenged this evidence, and consid...
متن کاملThe 12.9-ka ET Impact Hypothesis and North American Paleoindians
A hypothesized extraterrestrial impact in North America at ∼12,900 calendar years BP (12.9 ka) has been proposed as the cause of Younger Dryas climate changes, terminal Pleistocene mammalian extinctions, and a supposed “termination” of the Clovis archaeological culture. In regard to the latter, however, an examination of archaeological, geochronological, and stratigraphic evidence fails to prov...
متن کاملEvidence from central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis.
We report the discovery in Lake Cuitzeo in central Mexico of a black, carbon-rich, lacustrine layer, containing nanodiamonds, microspherules, and other unusual materials that date to the early Younger Dryas and are interpreted to result from an extraterrestrial impact. These proxies were found in a 27-m-long core as part of an interdisciplinary effort to extract a paleoclimate record back throu...
متن کاملPaleoindian demography and the extraterrestrial impact hypothesis.
Recently it has been suggested that one or more large extraterrestrial (ET) objects struck northern North America 12,900 +/- 100 calendar years before present (calBP) [Firestone RB, et al. (2007) Proc Natl Acad Sci USA 104: 16016-16021]. This impact is claimed to have triggered the Younger Dryas major cooling event and resulted in the extinction of the North American megafauna. The impact is al...
متن کاملLarge Pt anomaly in the Greenland ice core points to a cataclysm at the onset of Younger Dryas.
One explanation of the abrupt cooling episode known as the Younger Dryas (YD) is a cosmic impact or airburst at the YD boundary (YDB) that triggered cooling and resulted in other calamities, including the disappearance of the Clovis culture and the extinction of many large mammal species. We tested the YDB impact hypothesis by analyzing ice samples from the Greenland Ice Sheet Project 2 (GISP2)...
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ورودعنوان ژورنال:
- Proceedings of the National Academy of Sciences of the United States of America
دوره 106 43 شماره
صفحات -
تاریخ انتشار 2009