Holliday et al.'s Gish gallop: The end of Clovis
In fact, the YDIH doesn't claim the YD impact ended Clovis culture instantly. It merely proposes it affected the Clovis culture significantly, i.e. it was the beginning of the end for Clovis.
5.7. Improved Dating of Clovis Sites and Clovis Archaeology
Clovis is a term given to the oldest well-dated, widespread, and recognizable archaeological technocomplex in
North America (Haynes, 2002; Smallwood and Jennings, 2015; Meltzer, 2021). Proponents of the YDIH use their
perceived connection between the disappearance of the Clovis lithic tool style and the onset of the YD/GS-1 stadial
at ~12.9 ka BP as evidence for an environmental catastrophe (Sections 1, 3.1 and 3.2) (e.g., Firestone et al., 2006,
2007; Anderson et al., 2011; Wolbach et al., 2018b).
This is misleading as the date of the “YD/GS-1 stadial at 12.9 BP” is provided by Holliday et al. and is not
a date YDIH proponents adopt.
Powell (2020) repeats the notion of a non-existent mystery regarding the disappearance of Clovis archaeology
(Section 3.1). Subsequently, Powell (2022) is quite emphatic on this point. He refers to “the fall of Clovis” (p 35)
and claims (p 36) “just at its prime [~13 ka], Clovis suddenly fell” and “No Clovis artifacts have ever been found in
place above the YD” (presumably referring to the YDB). These claims are false.
This is also misleading. The most precise dating of the “fall of Clovis” is provided
by Waters et al. (2020). Powell’s comments above are consistent with their conclusions (see below).
The YDC is a time interval spanning ≈ 1200 calendar years. A broad variety of artifacts styles appeared and
disappeared during and after the span of the YD/GS-1 in North America. For example, most of the data used by
Anderson et al. (2011) are undated (and undatable) artifacts found on the surface. Radiocarbon dating of Clovis
sites (below) shows that Clovis persisted beyond the YDB.
This is, once again, misleading. Clovis artefacts might have persisted for a brief while after the YD onset,
but this is uncertain and does not contradict the YDIH. To my knowledge, no Clovis artefacts have ever been found
found above the YDB. See below.
Powell (2022, p 36) offers other unsubstantiated and factually incorrect claims regarding Clovis archaeology. “At
the Topper site, LeCompte et al. [2012] found impact microspherules touching Clovis artifacts, but no
microspherules below the artifact layer.” He apparently is unaware that the archaeologist who excavated the Clovis
and younger components at Topper documents the mixing of the assemblages (Miller, 2010). The context of
spherules in a single sample column is meaningless.
The spherules are thought to indicate the position of the YDB and are therefore not meaningless. In any
case, these observations are not inconsistent with the YDIH.
Powell (2022, p 36) further claims “In the Southeastern US, near the onset of the YD, the Clovis suddenly
abandoned a dozen Paleo-Indian chert quarries” with no citation. Topper was a quarry but also a primary habitation.
No Clovis quarries with firm age control are reported.
Again, these observations are not inconsistent with the YDIH.
More generally he notes “In the eastern US, Clovis artifacts have been found from Maine to Florida, where average
yearly temperatures differ by much more than the ~10◦C change at the beginning of the YD. Could such a relatively
small temperature change, even one that occurred rapidly, by itself have destroyed such a well-adjusted and
widespread culture?” Leaving aside the bizarre comment about a “well-adjusted” culture, the quote reveals a
misunderstanding of the difference between the annual cycle of temperature and changes in long-term mean global
annual temperatures. In any case, no data are provided to support these assertions.
No arguments or data are presented by Holliday et al. to refute the YDIH here either. Considering their
claim is to refute the YDIH, they are required to present dispositive evidence that contradicts the YDIH,
and so far they have failed to do so.
But Fastovich et al. (2020) and Griggs et al. (2022) show that environmental conditions across eastern North
America before, during, and after the YDC varied significantly in space and time. But the point is essentially moot.
Clovis populations survived across North America in highly varied and changing environments from before and into
the YDC (e.g., Haynes, 2002; Smallwood and Jennings, 2015).
While this might be true, it is not shown to be true and does not contradict the YDIH. See below.
Radiocarbon dating shows that there is no correlation between the YDB and the end of the Clovis archaeological
style.
This is false. See below.
The work of Waters and Stafford (2007) was accepted as a standard for the dating of the Clovis occupation of North
America by the YDIH proponents (e.g., Firestone et al., 2010a; Wittke et al., 2013a; Kennett et al., 2015a) although
their dating did not quite support the YDIH claims. Waters and Stafford (2007) suggest that Clovis occupied a
narrow time window between ~13.0 ka and ~ 12.6 ka. That age range was revised/updated and now indicates that
Clovis largely post-dates 12.9 ka by up to several centuries (Waters et al., 2020).
This is misleading. Age comparisons should be made with raw uncalibrated radiocarbon data. As
we shall see, the uncalibrated data provided by Waters et al. (2020) is consistent with the YDIH.
That paper (published before Sweatman, 2021, was submitted) …
Sweatman (2021) was focussed on the impact itself, not its secondary effects.
… proposes a maximum calibrated age range for Clovis of ~13,050 to ~12,750 cal yr BP. Their fig. 2 shows that
most of their dated sites post-date the YDB. Only one is clearly older.
Figure 2 from Waters et al. (2020) above clearly shows that they infer that a megafaunal extinction
coincides with the end of Clovis within dating uncertainties. It is important to note that the date of the
Younger Dryas onset depicted in this Figure is not the one adopted by proponents of the YDIH and is
shown without any uncertainty. In fact, Waters et al. (2020) conclude;
“Clovis — the technology — abruptly ends at ~12,750 cal yr B.P. and coincides temporally with the
beginning of the Younger Dryas cooling event and paleontologically, with the extinction of Mammut,
Mammuthus, and Cuvieronius. Archaeologically, Clovis terminates immediately before the emergence of
Folsom technology on the Plains (27, 46) and the eastern Fluted Point Tradition in the eastern United
States (47). In contrast, the production of stemmed points in the western United States continues after
Clovis ends (48).”
So it is clear that the view of Waters et al. (2020) is that the end of Clovis, a megafaunal extinction
event and the YD onset are essentially synchronous within dating uncertainty.
Figure 2 from Waters et al. (2020) shown above compares the onset of the Younger Dryas, a megafaunal
extinction and the end of Clovis on a calibrated age timescale. However, this comparison is best made with
uncalibrated ages to avoid confounding the issue with calibration uncertainty. Taking the
estimated age of the YDB from Kennett et al. (2015) of 12,735 - 12,835 +- 50 cal BP (2 sigma), we can
back-calculate the radiocarbon age using the same 2013 calibration curve to find the age of the YDB is
10,965 +- 1 C14 yr BP. Note, the uncertainty in the calibrated age is almost entirely due to the calibration
curve. If we compare this uncalibrated age with the uncalibrated average age for each Clovis group
investigated by Waters et al. (2020), we find that 8 out of 10 groups are consistent with an older age than the
YDB (at 2 sigma). The only groups with apparently younger average ages are those at Jake
Bluff (10,820 +- 10 C14 yr BP) and Cactus Hill (10,860 +- 20 C14 yr BP). Therefore, if we take these
radiocarbon results at face value, they are consistent with the YDIH which predicts that the YD impact
significantly affected the Clovis culture. It should be emphasized that the YDIH
does not predict that the impact wiped out Clovis entirely in an instant.
However, Waters et al. (2020) do not compare any of the archaeology or palaeontology to the YDB because
they do not locate the YDB at any site. Therefore, there remains some doubt about their results in terms of
synchroneity with the YD impact. As already emphasized several times, the archaeology, palaeontology and
paleoenvironmental indicators should always be related to the position of the YDB when assessing the
YDIH. To my knowledge, no Clovis artefacts have ever been found above the YDB.
Further, Buchanan et al. (2022), using recent dating of Folsom archaeology (Buchanan et al., 2021) along with the
work of Waters et al. (2020) demonstrate an overlap of the two artifact traditions by as much as 200 years,
discrediting the notion of an abrupt cultural termination at the YDB (and the notion of some sort of occupation
hiatus after the Clovis occupation, Section 1) (see also Barlow and Miller, 2022).
Here, Holliday et al. criticize observations that are not part of the YDIH. This is known as a ‘strawman’
fallacy. The YDIH makes no claims about other cultures.
In any case, HEA’s statement is at odds with Waters et al. (2020) who state that,
“Archaeologically, Clovis terminates immediately before the emergence of Folsom technology on the
Plains (27, 46) and the eastern Fluted Point Tradition in the eastern United States (47).”
One notable example of flawed dating ignored by the YDIH proponents is from the Gainey archaeological site in
Michigan (Table 4). This badly mixed Clovis site was repeatedly presented as a key locality supporting the YDIH
(Firestone et al., 2007; Bunch et al., 2012; LeCompte et al., 2012; Wittke et al., 2013a; Kennett et al., 2015a, 2015b)
although the absence of intact context at the site was emphatically stated by the archaeologists that investigated it
and repeatedly stated by YDIH critics (Holliday and Meltzer, 2010; Boslough et al., 2012; Holliday et al., 2014;
Meltzer et al., 2014). Significantly, the site is the only YDIH locality where purported impact indicators are directly
dated, yielding ages of ~200 and - 135 14C yr BP (Table 4). They are clearly not YDB age and one, from R.
Firestone, must be from a modern sample that included “bomb carbon” (from atmospheric testing of nuclear
weapons) which yields radiocarbon dates from the future, a well known problem in radiocarbon dating of young s
amples (Taylor and Bar-Yosef, 2014, p 23). Despite the obvious damning data on the context and age of the site,
some years after it was published, YDIH proponents continued to maintain that it is a YDB site (Kennett et al.,
2015a, SI pS34; Powell, 2022).
These dates are so obviously inconsistent with the YDB that they can be disregarded. Probably, these
samples have been mishandled and contaminated.
Summary
Holliday et al., consistently misrepresent the YDIH and consistently misunderstand how to analyse radiocarbon data. The best evidence to date for the end of Clovis by Waters et al. (2020) is completely in accordance with the YDIH. One possibility, if we take the radiocarbon dates at face value, is that Clovis culture survived in pockets after the impact event for perhaps one or two more centuries, but eventually the catastrophic changes in their environment forced them to change and adapt. However, the YD boundary was not located by Waters et al. (2020) in their work and errors with the radiocarbon dates are entirely feasible, so synchroneity of the end of Clovis with the YD impact cannot be ruled out by this evidence alone. To my knowledge, Clovis artefacts have never been found above the YDB.
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