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The cold period known as the Younger Dryas (YD)
climate oscillation occurred between c. 12.9 ka
BP and c. 11.7 ka BP (e.g. Berger 1990; Peteet
1995; Bj¨orck 2007; Lowe et al. 2008). This sudden
climate change is generally thought to result from
an abrupt change of atmospheric and oceanic
circulations (e.g. Teller et al. 2002; McManus
et al. 2004; Brauer et al. 2008). The beginning
of the YD in North America can at times be
stratigraphically marked by the so-called black mat,
a thin dark layer of organic-rich material (e.g.
Firestone et al. 2007; Haynes 2007, 2008; Pigati
et al. 2009, 2012). The black mat, however, is a
general term that includes, in addition to the dark
organic-rich deposits, some marls and diatomites
that are light grey in color (e.g. Ballenger et al.
2011). A lot of attention was lately paid to the
black mat because of a widespread discussion on
the possibility of the extraterrestrial impact shortly
before the onset of the YD climate oscillation
(e.g. Firestone et al. 2007; Haynes et al. 2010;
Pigati et al. 2009, 2012; Andronikov et al. 2011,
2014; Fayek et al. 2012; Kennett et al. 2015).
There are reports about findings of unusual objects
such as carbon spherules, nanodiamonds, glasslike
carbon, melt-glass, as well as enhanced
amounts of platinum group elements in sediments
corresponding to the lower YD boundary (LYDB) in
support of the hypothesis (e.g. Firestone et al. 2007;
Kennett et al. 2009; Mahaney et al. 2010, 2013;
Bunch et al. 2012; Petaev et al. 2013; Wu et al.
© 2016 Swedish Society for Anthropology and Geography 1
DOI:10.1111/geoa.121222013). One such characteristic object reported is
magnetic microspherules (e.g. Firestone et al. 2007;
Israde-Alc´antara et al. 2012; LeCompte et al. 2012;
Wittke et al. 2013).
Strongly elevated concentrations of the magnetic
microspherules in a thin sandy layer corresponding
to the LYDB are revealed for the BWD-1
sedimentary sequence. Sharp increase of the
number of microspherules in sediments located
along the LYDB is in agreement with observations
made by Firestone et al. (2007, 2010) and
LeCompte et al. (2012). Because overall close
chemical, mineralogical, and structural similarity
of the BWD-1 hollow microspherules to those
directly related to known meteorite occurrences
and/or meteoritic events, the cosmic origin of the
former seems to be a credible hypothesis. If we
accept such origin of the BWD-1 microspherules,
then ablation of iron or stony meteorites during their
passage through the Earth’s atmosphere seems to be
the most plausible mechanism for their formation.
However, the exact mechanism of the formation
of the magnetic microspherules is not completely
clear. In addition to the formation during ablation
of the meteoritic body in the Earth’s atmosphere
(as in the case of the microspherules studied), they
could be produced during the airburst of such a
body, or could result from the impact of the ET
body. When meteorite influx increases, it results,
in particular, in elevated concentration of the
hollow magnetic microspherules in discrete layers
of terrestrial sediments. The elevated concentration
of microspherules of the BWD-1 type is a
known phenomenon for multiple LYDB locales
across North America (e.g. Firestone et al. 2007;
LeCompte et al. 2012; Pigati et al. 2012; Wittke
et al. 2013). The presence of the high number of
such microspherules in the sediments can serve
as a local stratigraphic marker in identification
of the LYDB there where dark variety of the
black mat is absent. If one applies methods of
microstratigraphy to paleosols of the suggested
(LYDB) age, the strongly elevated concentrations
of magnetic microspherules would mark precisely
the time of around 12.9 ka BP. The data from
the present study along with observations made
on sediments around the LYDB elsewhere suggest
that some unusual event took place just before the
onset of the YD climate oscillation. However, an
understanding of what happened at c. 12.9 ka BP
and how it is related (if at all) to the onset of the
YD climate oscillation requires further search.
that is in fact blatantly untrue.
No skeletal remains of horse, camel, mammoth, mastodon, dire wolf, American lion, short-faced bear, sloth, tapir, etc:, or Clovis artifacts have ever been found in situ within the YD age black mat,
and what bearing does that have on the question.
and no post-Clovis Paleoindian artifacts have ever been found in situ stratigraphically below it.
originally posted by: punkinworks10
The skeptics are cherry picking the data every bit as bad as the stichinites and all their ilk do.