A
Guest Document
INTRODUCTION
by The
M+G+R
Foundation
We have come across this highly scientific study which further confirms
our position regarding the timing for the last Reset of Creation which
we published elsewhere
- thus we wish to share it with our readers.
The less technical reader can skip over the details and read the logic
behind their conclusions.
Terrestrial
Evidence of a Nuclear Catastrophe in Paleoindian Times
by Richard B. Firestone & William
Topping
Mammoth Trumpet
Volume 16, Number 2 March 2001
from Center First Americans Website (0)
CONTENTS
The Paleoindian
occupation
of North America, theoretically the point of entry of the first
people to the Americas, is traditionally assumed to have occurred
within a short time span beginning at about 12,000 yr B.P.
This is inconsistent with much older South American dates of around
32,000 yr B.P. (1)
and the similarity of the Paleoindian toolkit to
Mousterian traditions that disappeared about 30,000 years ago. (2)
A pattern of unusually young radiocarbon dates in the Northeast has
been noted by Bonnichsen and Will. (3)(4)
Our research indicates that the entire Great Lakes region (and beyond)
was subjected to particle bombardment and a catastrophic nuclear
irradiation that produced secondary thermal neutrons from cosmic ray
interactions.
The neutrons produced unusually large quantities of 239Pu
and
substantially altered the natural uranium abundance ratios (235U/238U)
in artifacts and in other exposed materials including cherts,
sediments, and the entire landscape.
These neutrons necessarily transmuted residual nitrogen (14N)
in the
dated charcoals to radiocarbon, thus explaining anomalous dates.
The evidence
from dated materials
We investigated a cluster of especially young radiocarbon dates
concentrated in the north-central area of North America.
For example, at the Gainey site in Michigan a 2880 yr B.P. radiocarbon
date was reported, while the thermoluminescence date for that site is
12,400 yr B.P. (5)
Other anomalous dates found at Leavitt in Michigan, (6)
Zander and Thedford in Ontario, (7)
Potts in New York, (8)
Alton in Indiana, (9)
and Grant Lake in Nunavut (10)
are summarized in Table 1.
The Grant Lake Paleoindian site is most remarkable because its 160 [rc]
yr B.P. age is nearly contemporary, while adjacent and deeper samples
give ages of 1480-3620 [rc] yr B.P.
Stratigraphic associations place Paleoindian occupations at depth on
the prehistoric North American landscape on sediments that form the old
C horizon composed of parent material, Wisconsinan deposits that
predate Holocene sediment buildup. (11)(12)(13) The young
Paleoindian dates
cannot be correct, particularly since there are no patterned anomalies
noted in later-period prehistoric assemblages relating to higher
stratigraphic positions.
In a pioneering study of the Paleoindian site at Barnes, Michigan,
Wright and Roosa observed that Paleoindian artifacts were deposited
before the formation of spodosols ceased in this area about 10,000 yr
B.P. (14)
This conclusion was based on observing that cemented sediments on
artifacts, found outside their original context, defines their original
stratigraphic position.
The evidence
from particle
bombardment
Sediment profiles were taken at Paleoindian sites and at numerous
widely separated control locations in Michigan.
The C sediment horizon is clearly recognized by its transitional color
and confirmed by elevated concentrations of potassium and other
isotopes. Color and chemistry are key indicators of this very old
soil (11)(12)(13)(14)
derived from parent materials and associated
postglacial runoff. (15)
At Gainey, large quantities of
micrometeorite-like particles appear to be concentrated near the
boundary between the B and C sediment horizons.
They can be separated with a magnet and are identified by the presence
of chondrules and by visual evidence of sintering and partial melting.
These particles, dissimilar to common magnetites, are found in
association with a high frequency of "spherules." The depth profiles
for potassium and particles at the Gainey site are compared in Fig. 1.
Minor vertical sorting of particles is apparent, with a shallow spike
of particles near the surface probably resulting from modern
agricultural or industrial activity. Total gamma-ray counting of
sediment profiles in the various locations invariably showed increased
radioactivity at the B-C boundary consistent with enhanced potassium
(40K) and possibly other activities.
Microscopic examination of chert artifacts from several widely
separated Paleoindian locations in North America revealed a high
density of entrance wounds and particles at depths that are evidence of
high-velocity particle bombardment. Chondrules were identified
visually; their presence necessarily indicates heating during
high-speed entry into the atmosphere.
The depth of penetration into the artifacts implies that the particles
entered with substantial energy. (16) Field simulations with
control
cherts for large particles (100-200 microns) suggest an entrance
velocity greater than 0.4 km/s, and experiments at the National
Superconducting Cyclotron Laboratory indicate that the smaller
particles left tracks comparable to about 526 MeV iron ions (56Fe)
in
Gainey artifacts.
Similar features are not observed in later-period prehistoric artifacts
or in bedrock chert sources. Track angles were estimated visually;
track densities were measured with a stage micrometer; track depths
were found by adjusting the microscope focus through the track.
These data are summarized in Table 1.
Track and particle data in Table 1 suggest that the total track volume
(density times depth) is highest at the Michigan, Illinois, and Indiana
sites and decreases in all directions from this region, consistent with
a widespread catastrophe concentrated over the Great Lakes region.
The nearly vertical direction of the tracks left by particle impacts at
most sites suggests they came from a distant source.
A barn is a unit of area equal to 10-24 cm2, used
in nuclear physics.
The fraction of isotopes that are transformed by a nuclear reaction is
given by s x I, where s is the cross section in cm2
of the target
presented by an atom, and I is the neutron flux per cm2
impinging on
the target. Most neutron-induced reactions involve the capture of a
neutron to produce a heavier isotope of the same element.
Exceptions include 14N, which captures a neutron and emits
a proton to
produce 14C; and 235U, which mainly fissions
into two lighter elements.
The relative size of isotopes in chert is shown in figure "A neutron's
view of chert."
The evidence
from uranium and
plutonium
Natural uranium, which is ubiquitous in cherts, has a 235U/238U
isotopic ratio of 0.72 percent, which varies by less than 0.1 percent
in natural sources. (17)
Significant variations in the isotopic ratio do not occur because of
chemical processes; however, a thermal neutron bombardment depletes 235U
and thus alters the ratio. Solar or galactic cosmic rays
interacting with matter produce fast secondary neutrons that become
thermalized by scattering from surrounding materials.
Thermal neutrons see a target of large cross section (681 barns) A for
destroying 235U, compared with a target of only 2.68 barns
for neutron
capture on 238U. Therefore, despite the low abundance of 235U,
about
1.8 times as many 235U atoms are destroyed as 238U
atoms by thermal
neutrons.
If a large cosmic-ray bombardment impacted the earth and irradiated the
prehistoric landscape with thermal neutrons, the 235U/238U
ratio would
be changed; 239Pu would be produced from neutron capture on
238U,
followed by the decay of 239U. Neutrons colliding with
nitrogen (1.83
barns) would create 14C in exactly the same way 14C
is normally
produced in the upper atmosphere, necessarily resetting the radiocarbon
dates of any organic materials lying near the surface on the North
American prehistoric landscape--including charcoals at Paleoindian
sites--to younger values.
239Pu produced during the bombardment will also be partly
destroyed by
thermal neutrons with 1017 barn cross section.
Assuming 239Pu doesn't mobilize, it will decay back to 235U
(half-life
24,110 yr), partially restoring the normal abundance.
Paleoindian artifacts
from Gainey, Leavitt, and Butler, and two
later-period artifacts from the same geographic area of Michigan were
analyzed for 235U content by gamma-ray counting at the
Phoenix Memorial
Laboratory, University of Michigan.
They were compared with identical chert types representative of the
source materials for the artifacts. Control samples were extracted from
the inner core of the purest chert known to be utilized by prehistoric
people.
The Paleoindian artifacts contained about 78 percent as much
235U as
the controls and later-period artifacts, suggesting substantial
depletion. Depletion of 235U necessarily indicates that
thermal
neutrons impacted these artifacts and the surrounding prehistoric
landscape.
Various artifacts, cherts, sediments, and a control sample containing
about 0.2 percent uranium obtained from uraninite were sent to the
McMaster University Centre for Neutron Activation Analysis to determine
235U concentration by delayed neutron counting and 238U
concentration
by activation analysis. These results are shown in Table 2. The 235U/238U
ratios for all samples except the control deviated
substantially from the expected ratio.
McMaster ran additional calibration standards and has considerable
expertise analyzing low-level uranium.
This analysis was sensitive to a few ppb for 235U and
0.1-0.3 ppm for 238U, more than sufficient to precisely
analyze the uranium-rich chert
samples (0.7-163.5 ppm).
Most samples were depleted in 235U, depletion increasing
geographically
from the southwest (Baker, Chuska chert, 17 percent) to the northeast
(Upper Mercer, 77 percent), as shown in Table 2.
This is consistent with cosmic rays focused towards northern latitudes
by Earth's magnetic field. Only a very large thermal neutron flux,
greater than 1020 n/cm2, could have depleted 235U
at all locations.
Samples of unaltered flakes from Taylor and sediment originally
adjacent to Gainey artifacts showed 235U enriched by 30
percent.
Both samples were closely associated with the particles described
above. The position of these samples appears to be related to the
enrichment, which cannot be explained by thermal neutrons from the
bombardment. To test this, we bathed another Taylor flake in 48-percent
HF at 60°F for ten minutes to remove the outer 70 percent of the
sample and the attached particles. Analysis showed the "inner" flake
depleted in 235U by 20 percent, consistent with the other
depleted
cherts.
Samples of Gainey sediment and Taylor flakes were analyzed for
plutonium by Nuclear Technology Services, Inc., of Roswell, Georgia,
which specializes in radiochemistry using standard methodology. The
plutonium, with an aliquot of NIST-traceable 242Pu added, was
chemically separated on an anion exchange resin column and counted on
an alpha-particle spectrometer. The 239Pu/238U
ratios in both samples
were approximately 10 ppb, vastly exceeding the expected ratio of 0.003
ppb. (18) The
results of this analysis are shown in Table 2.
Chert is a glass-like material highly impervious to penetration by any
nuclear fallout that might also contribute 239Pu. We
analyzed a
long-exposed piece of Bayport chert by gamma-ray counting at the LBNL
low-background facility for the presence of cesium-137 (137Cs), a key
indicator of fallout (from nuclear testing), and found none. The B-C
interface typically lies sufficiently deep that contamination by
fallout is improbable. It is important to note that fallout cannot
explain the depletion of 235U.
Since the depletion of 235U must have resulted from
bombardment by
thermal neutrons, the presence of 239Pu from irradiation of
238U is
expected. The total thermal neutron flux required to produce the
observed 239Pu concentration can be calculated from the
relative
concentrations of 239Pu (corrected for the decay) and 238U,
and the
thermal neutron-capture cross section for 238U.
This neutron flux can then be used to estimate the amount of additional
14C that would have been produced in charcoal by neutrons
colliding
with 14N (14N cross section = 1.83 barns).
The corrected radiocarbon age can then be estimated by comparing the
current amount of 14C in the dated charcoals, determined
from their
measured radiocarbon age, with the amount of 14C that would
have been
produced by the bombardment. For these calculations we assume that
charcoal contains 0.05 percent residual nitrogen (19) and that initial 14C
concentrations were the same as today (one 14C atom for
1012 12C atoms).
We derive a thermal neutron flux of c. 1017 n/cm2
at Gainey,
which
corresponds to an approximate date of 39,000 yr B.P. No radiocarbon
date is available for the more southerly Taylor site, but for the
conventional range of accepted Paleoindian dates the neutron flux would
be c. 1016 n/cm2, giving a date of about 40,000
yr B.P.
These
calculations necessarily neglect differences in the neutron flux
experienced by the dated charcoal and the artifacts, the effects of
residual 239Pu from previous bombardments, and loss of 239Pu
due to
leaching from chert over time.
The neutron flux calculated from the 235U/238U
ratio is more than 1000
times that implied by the level of 239Pu. Since 239Pu
decays to 235U,
partly restoring the natural abundance, it appears that substantial
quantities of 239Pu have migrated out of the chert.
This mobility is demonstrated at the Nevada Test Site, where plutonium,
produced in nuclear tests conducted by the U.S. between 1956 and 1992,
migrated 1.3 km. (20)
It has also been shown that atoms produced by radioactive decay or
nuclear reaction become weakly bound to the parent material and pass
more readily into solution than isotopes not affected. (21) Both 239Pu
and 235U are thus expected to be mobile, complicating any
analysis. This is
consistent with the enrichment of 235U in the two external
samples
where migrating 239Pu or 235U may have been
trapped, thus enriching the
relatively uranium-poor outer regions. Alternatively, excess 235U
may
have been carried in by the particles. Radiocarbon produced in situ by
irradiation should also be mobile.
If 14C is more mobile than 239Pu, then the
dates calculated above
should be decreased accordingly.
Redating North
American sites
The 39,000 yr B.P. date proposed for the Gainey site is consistent with
the prevailing opinion among many archaeologists about when the
Americas were populated. It is also commensurate with dates for South
American sites and with a Mousterian toolkit tradition that many see as
the Paleoindian precursor.
The proposed date for the Gainey site also falls closer in line with
the radiocarbon date for a Lewisville, Texas, Paleoindian site of
26,610 ± 300 yr B.P. (22)(23)(24) and radiocarbon dates
as early as c. 20,000
yr B.P. for Meadowcroft Rockshelter. Since the Lewisville and
Meadowcroft sites were likely exposed at the same time to thermal
neutrons, we estimate that their dates should be reset to c. 55,000 yr
B.P. and c. 45,000 yr B.P., respectively.
It is likely that Paleoindians
occupied low latitudes during the full
glacial and migrated to more northerly areas as the ice front
retreated. Therefore the pattern of dates makes sense from the
archaeologist's point of view. Dates for North American sites should
generally be reset by up to 40,000 years, depending on latitude and
overburden.
Geologists believe that before c. 15,000 yr B.P. the Wisconsinan
glaciation covered the more northerly locations where Paleoindian sites
have been found. (25)
The ice sheet would have shielded the landscape and
any artifacts from an irradiation.
(The Gainey thermoluminescence date of 12,400 yr B.P. is probably a
result of the heat generated by the nuclear bombardment at that time,
which would have reset the TL index to zero.)
The modified dates for Paleoindian settlements suggest that the
timetable for glacial advance sequences, strongly driven by
conventional radiocarbon dates, should be revisited in light of the
evidence presented here of much older occupations than previously
thought."
The alignment of magnetic particles in sediment indicates that the
Earth's magnetic poles have repeatedly reversed their polarity in the
past. Complete magnetic excursions occurred about 10 times in 4.5
million years; the last reversal occurred about 700,000 years ago.
Magnetic excursions occur every 10,000-20,000 years when the Earth's
magnetic field becomes weak, and the poles may even reverse for a short
time.
The evidence
from tree rings and
marine sediments
A large nuclear bombardment
should have left evidence elsewhere in the
radiocarbon record. It is well known that radiocarbon dates are
increasingly too young as we go back in time.
The global Carbon Cycle suggests that 14C produced by
cosmic rays would
be rapidly dispersed in the large carbon reservoirs in the atmosphere,
land, and oceans. (26)
We would expect to see a sudden increase in radiocarbon in the
atmosphere that would be incorporated into plants and animals soon
after the irradiation; after only a few years, most of the radiocarbon
would move into the ocean reservoirs. The 14C level in the
fossil
record would reset to a higher value.
The excess global radiocarbon would then decay with a half-life of 5730
years, which should be seen in the radiocarbon analysis of varved
systems.
Fig. 2 plots 14C from the INTCAL98 radiocarbon age
calibration data of
Stuiver et al. for 15,000-0 yr B.P. (27) and Icelandic marine
sediment 14C
data measured by Voelker et
al. for 50,000-11,000 yr B.P. (28)
Excess 14C is indicated by the difference between the
reported
radiocarbon dates and actual dates. Sharp increases in 14C
are apparent
in the marine data at 40,000-43,000, 32,000-34,000 and c. 12,000 yr B.P
These increases are coincident with geomagnetic excursions B that
occurred at about 12,000 (Gothenburg), 32,000 (Mono Lake), and 43,000
yr B.P. (Laschamp), (29)
when the reduced magnetic field would have made
Earth especially vulnerable to cosmic ray bombardment. The interstitial
radiocarbon data following the three excursions were numerically fit,
assuming exponential decay plus a constant cosmic ray-produced
component. The fitted half-lives of 5750 yr (37,000-34,000 yr B.P.),
6020 yr (32,000-16,000 yr B.P.), and 6120 yr (12,000-0 yr B.P.) are in
good agreement with the expected value.
We also determined that contemporary radiocarbon contains about 7
percent residual 14C left over from the catastrophe. The
constant
cosmic ray production rate was about 34 percent higher for the
Icelandic sediment than the INTCAL98 samples, perhaps implying higher
cosmic ray rates farther north. Disregarding fluctuations in the data
from variations in ocean temperatures and currents, the results are
clearly consistent with the decay of radiocarbon following the three
geomagnetic excursions.
In Fig. 2, the sharp drop in 14C activity before 41,000 yr
B.P.
suggests that global radiocarbon increased by about 45 percent at that
time and by about 20 percent at 33,000 and 12,000 yr B.P The results
are remarkably consistent with Vogel's comparison of 14C
and U-Th dates
of a stalagmite that indicates global radiocarbon increased about 75
percent from 30,000 to 40,000 yr B.P. and about 30 percent around
18,000 yr B.P. (30)
McHargue et al. found high
levels of 10Be in Gulf of California marine
sediments at 32,000 and 43,000 yr B.P.C that could not be explained by
magnetic reversal alone and were attributed to cosmic rays, possibly
from a supernova. (29)
The geomagnetic excursion at 12,500 yr B.P.
coincides with the thermoluminescence date from Gainey, and additional
evidence for a cosmic ray bombardment at that time is found in the
increases of 10Be, (31)
Ca, (32) and Mg32
in Greenland ice cores around
12,500 yr B.P. Similar increases are also seen in the data for NO3-,
SO4-, Mg+, Cl-, K+, and Na+ ions in Greenland ice cores. (33)
This occurrence can be dated precisely to 12,500 ± 500 yr B.P., an
average of the remarkably consistent concentration peak centroids in
the Greenland ice core data. Significant increases at that time are not
found in comparable data for the Antarctic, which indicates that the
cosmic ray irradiation was centered in the Northern Hemisphere. Weak
evidence of an occurrence at 12,500 yr B.P. is seen in the radiocarbon
record for marine sediments near Venezuela, (34) confirming that the
cosmic ray bombardment was most severe in northern latitudes.
Lunar cosmogenic data also show evidence of increased solar cosmic ray
activity at or before 20,000 yr B.P. (35)(36) although these data
are not
sensitive to earlier irradiation.
Beryllium occurs naturally as 9Be. 10Be is
produced by cosmic rays,
mostly protons, striking the atmosphere and breaking apart nitrogen and
oxygen. It has a half-life of 1.5 million years. Unlike 14C,
which is
caught up in the global Carbon Cycle, 10Be is inert and
falls as dust. 10Be is produced almost entirely by galactic
cosmic rays, which are
much higher in energy than solar cosmic rays.
Thus any increase in 10Be would be cosmic in origin; and
the cosmic ray
rate could only change if there were a nearby supernova. During the
last Ice Age the 10Be deposition rate in ice at both poles
was much
higher than today. Gulf of California marine sediments clearly show
strong (10).
Be peaks at 32,000 and 43,000 yr B.P.
McHargue argues that these peaks
can only be explained by a supernova.
The effect of a
supernova on Earth
Sonett suggests that a single
supernova would produce two or three
shock waves, an initial forward shock and a pair of reverse shocks from
the initial expansion and a reflected wave from the shell boundary of a
more ancient supernova.39,40
Fig. 2 shows that each episode in a series produced a similar amount of
atmospheric radiocarbon.
The sun lies almost exactly in the center (41) of the Local Bubble,
believed to be the result of a past nearby supernova event. A candidate
for the reverse shock wave is the supernova remnant North Polar Spur,
with an estimated age of 75,000 years and a distance of 130 ± 75
parsecs (424 light years), (42)
conveniently located in the north sky from
where it would have preferentially irradiated the Northern Hemisphere.
Assuming the Taylor flux is
average and 1,000 neutrons are produced per
erg of gamma-ray energy, (43)
the catastrophe would have released about
1016 erg/cm2 (2 x 108 cal/cm2),
corresponding to
a solar flare of 1043
ergs or a gamma-flash of 1054 ergs from a supernova about 1
parsec away.
The geographical distribution of particle tracks, 235U
depletion, and 239Pu concentration shown in Fig. 3 are
quite consistent, although the
particle tracks seem to be confined to a smaller geographic area.
They indicate energy released over the northeastern sector of the U.S.,
with maximum energy at about 43° N, 85° W, the Michigan area of the
Great Lakes region.
A history of
suspected cosmic
cataclysms over the ages
Wdowczyk and Wolfendale (44)
and Zook (36)
propose, based on the existing
record of solar flare intensities, that solar flares as large as 3 x
1038 ergs should be expected every 100,000 years.
Clark et al. estimate that supernovas release 1047-1050
ergs within 10
parsecs of Earth every 100 million years. (45) Brackenridge suggests
that
a supernova impacted the earth in Paleoindian times. (46)
Damon et al. report evidence
from the 14C tree ring record that SN1006,
which occurred at a distance of 1300 parsecs, produced a neutron shower
of 2 x 108 n/cm2. (47)
Castagnoli et al. report
evidence of the past six
nearby supernovae from the thermoluminescence record of Tyrrhenian sea
sediments. (48)
Dar et al. suggest that a cosmic ray jet within 1000 parsec would
produce 1012 muons/cm2 (greater than 3 x 109
eV) and 1010
protons and
neutrons/cm 2 (greater than 106 eV) and deposit over 1012
erg/cm2
in
the atmosphere every 100 million years. (49) A cosmic ray jet is
also
predicted to produce heavy elements via the r-process and could be a
source of 235U enriched up to 60 percent in uranium.
The Paleoindian catastrophe
was large by standards of all suspected
cosmic occurrences. Normal geomagnetic conditions would focus cosmic
rays towards the magnetic poles, concentrating their severity in those
regions. However, low magnetic field intensity during a geomagnetic
excursion may have allowed excessive cosmic rays to strike northeastern
North America. (Whether the geomagnetic excursion admitted cosmic
radiation, or the radiation caused the excursion, is uncertain. Given
our present state of knowledge, cause and effect in this instance are
unclear.)
The presence of a nearby small and dense interstellar cloud may explain
the origin of the particle bombardment. (50) The size of the initial
catastrophe may be too large for a solar flare, but a sufficiently
powerful nearby supernova or cosmic ray jet could account for it.
It appears that the catastrophe initiated a sequence of events that may
have included solar flares, impacts, and secondary cosmic ray
bombardments.
A devastating
effect on Earth
The enormous energy released by the
catastrophe at 12,500 yr B.P. could
have heated the atmosphere to over 1000°C over Michigan, and the
neutron flux at more northern locations would have melted considerable
glacial ice. Radiation effects on plants and animals exposed to the
cosmic rays would have been lethal, comparable to being irradiated in a
5-megawatt reactor more than 100 seconds.
The overall pattern of the catastrophe matches the pattern of mass
extinction before Holocene times. The Western Hemisphere was more
affected than the Eastern, North America more than South America, and
eastern North America more than western North America. (51)(52)(53)
Extinction in the Great Lakes area was more rapid and pronounced than
elsewhere.
Larger animals were more affected than smaller ones, a pattern that
conforms to the expectation that radiation exposure affects large
bodies more than smaller ones. (54)(55)
Sharp fluctuations of 14C in the Icelandic marine sediments
at each
geomagnetic excursion are interesting; because global carbon deposits
in the ocean sediments at a rate of only about 0.0005 percent a year, a
sudden increase in sediment 14C may reflect the rapid
die-off of
organisms that incorporated radiocarbon shortly after bombardment.
Massive radiation would be expected to cause major mutations in plant
life. Maize probably evolved by macro-mutation at that time, (55)(56) and
plant domestication of possibly mutated forms appears worldwide after
the Late Glacial period.
For example, there was a rapid transition from wild to domesticated
grains in the Near East after the catastrophe. (57)
Implications
for future study
Much of what we assume about the Paleoindian period and the peopling of
the Americas has been inferred from conventional radiocarbon
chronology, which often conflicts with archaeological evidence.
This work mandates that conventional radiocarbon
dates be reinterpreted
in light of hard terrestrial evidence of exposure of the
radiocarbon
samples to a cosmological catastrophe that affected vast areas of North
America and beyond.
A nuclear catastrophe can reset a group of unrelated artifacts to a
common younger date, creating gaps and false episodes in the fossil
record. Geographical variation and complicated overburdens may further
confuse the interpretation.
Scrutiny of Paleoindian artifacts and the North American
paleolandscape, associated stratigraphic sediments, coupled with
continued radiological investigations, may provide more evidence for
the cosmic catastrophe and new clues to the origin of Paleoindians.
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