Site importance
Meadowcroft Rockshelter in Pennsylvania
has become one of the most celebrated archaeological sites in the Americas. The
now accepted date of initial occupation of approximately 16000 years BP is the
oldest in North America.
Meadowcroft holds the distinction of demonstrating the longest occupational
sequence of humans in the Americas1&2. The numerous occupation
layers contained over 2,000 stone flakes and tools, 150 fire pits and 1 million
animal and plant remains. A heavily cut and burnt deer antler base, dated to
16,175±975 years BP was the oldest bone found at the site3. Additional finds included basketry, the area's earliest corn
maize dating to the 300's B.C.E., the area's earliest squash and pottery, dating
back to about 1000 B.C.E.. Brian Fagan former lecturer at both the Smithsonian
Institution, and the Getty Conservation Institute says “Meadowcroft is the
single most complex archaeological excavation I have ever seen,” said
world-renowned author and New World habitation expert Brian Fagan. “It’s a
classic example of the very best in stratigraphic observation and meticulous
recording in the field. The superb excavation methods give one great confidence
in the important evidence for the first Americans found in the bottom layers of
the site.”4
View of rockshelter during
excavation
Photo credit: Simon Fraser
University Museum of Archaeology & Ethnology
View of Meadowcroft seen from the
opposite side of Cross Creek April 1975
Photo credit: Mark McConaughy14
Discovery
The story of the discovery of the
site’s significance is an interesting one. Albert Miller, a native of
Washington County whose family have owned the area around the cave since 1795
was an amateur archaeologist, naturalist, local historian and farmer.
Born in 1911 he witnessed
first-hand the revolution in mechanised farming which swept through the United
States in those years, it was these huge changes and the loss of traditional
ways of life that inspired him to begin documenting rural life. He wrote later
that he “…became enamored of the idea of how old rural
and farm building[s], farm machines, tools and methods might be preserved. I
felt that the day would come when demonstrations of the past would fascinate
people of all ages.”5
The idea set in motion the
creation of the future museum at Meadowcroft and the non-profit Meadowcroft
Foundation, of which Delvin and Albert were president and vice president
respectively. Incidentally Meadowcroft was conceived of as a name by Albert and
his brother, Delvin from a contraction of their two adjacent farm names:
Meadowlands and Bancroft.
In 1955 whilst out with his dogs
Miller noted that a large groundhog hole in the vicinity of what would later
become known as Meadowcroft Rockshelter had what appeared to be prehistoric
debris in the excavated earth, reaching further in he retrieved a pre-historic
flint knife. Further evidence came to light in 1967 when Miller enlarged a
Badger hole and found lithic flakes, shells and animal bones. To him this
proved the pre-historic occupation of the shelter. He thus reported his find to
local archaeologists. Five years later, in 1973, a young University of
Pittsburgh anthropology professor named Dr. James Adovasio, visited the farm
and was shown the original pre-historic flint knife. Astonished by the find,
and realising its significance, Adovasio made an application to the Meadowcroft
Foundation (essentially Albert and his brother Delvin) to begin excavations.
These begun in the summer of 1973 and continued for six years.
Site description and
finds
The Meadowcroft Rockshelter is a
cave site c. 48km southwest of Pittsburgh near the village of Avella in
Washington County, Pennsylvania. The cave itself is on the north bank of Cross
Creek, a tributary of the Ohio River.
The surface rocks of this region
are layered sedimentary rocks of Middle to Upper Pennsylvanian Age (Casselman
Formation). The predominant lithologies are shale, quartz sandstone, limestone,
and coal in decreasing order of abundance.
Geologically, Meadowcroft is
located in the unglaciated portion of the Appalachian or Allegheny Plateau, west
of the valley and ridge province of the Appalachian Mountains, and northwest of
the Appalachian Basin.
Present topography was probably
generated during the Pleistocene when increased precipitation and runoff caused
extensive downcutting. Since the Wisconsin Glacial boundary only extends
southward to northern Beaver County (some 40 odd km north), the Cross Creek
Valley and Meadowcroft Rockshelter probably existed in nearly their present
configuration well before the close of the Wisconsin, ca. 11,000 B.P11.
It is notable that the area was
not a glaciated one but within close proximity to it lay the Laurentide Ice
Sheet. This undoubtedly affected the paleoclimate to a lesser or greater
extent.
Location of Meadowcroft
Rockshelter with respect to the maximum extent of the Laurentide Ice Sheet c.
20000ya. Credit: Adovasio 20026.
The excavation slowly uncovered
11 stratigraphic levels with stratum XI being at the top, or current ground
surface, whilst stratum I was found to be the lowest. Finds were made in all
levels, including level I. From Adovasio 1975:
“Extent: This, the basal stratum at the site, has been exposed thus far
only outside the drip line in a limited section of "deep-hole." It
lies directly beneath Stratum II and is presumed to be continuous across the
site. The large roof fall on the western edge of the site rests on the surface
of this stratum.
Composition: Stratum I consists of badly decomposed, foliated
sandstones (possibly roof fall?) interbedded with lenses of charcoal.
Compositional analysis of this unit is presently incomplete.
Associations: The upper 1,0 cm of this unit contains 5 lithic artifacts
which may represent intrusions from Stratum IIb, otherwise this unit is
sterile.”
Crucially sufficient charcoal was
discovered for radiocarbon dating. Lithic artifacts (stone flakes) were also
found. In this context ‘lithic artifacts’ means the excavator believes that the
flakes recovered are of human manufacture. Charcoal lenses can be read as
hearths or fires.
Of stratum II the report says:
“Stratum II Extent: Thickness of this unit varies from 40-120 cm. The
upper 50 cm are distinguished as Stratum Ha which is continuous across the
site. IIa is separated from the lower deposits (lIb) by massive roof fall. IIb
has been exposed thus far only outside the drip line in the
"deep-hole," Stratum II lies above Stratum I and directly beneath
Stratum III. Associations: Lithe materials, bone, firepits and fire floors,
floral remains, shell.”
The lithics and other artifacts excavated
contained some fine specimens:
Selected Bifaces from Paleoindian
levels. Mungai Knife is the centre biface.
Photo source: Mark McConaughy14
Lamellar Blades from Paleoindian
levels.
Photo source: Mark McConaughy14
Lithic Assemblage from
Meadowcroft Rockshelter.
The now famous Miller Lanceolate
point, named for Albert Miller, is at left.
Photo source: Mark McConaughy14
(Original source: Heinz History Centre)
Large Basketry Fragment
photographed in situ at Meadowcroft Rockshelter.
Photo source : Meadowcroft a
pre-Clovis site15 (Original source Meadowcroft Rockshelter and
Historic Village Collection. Heinz History Centre)
Corn Cob Fragments from Meadowcroft
Rockshelter
Photo source : Meadowcroft a
pre-Clovis site15 (Original source Meadowcroft Rockshelter and
Historic Village Collection. Heinz History Centre).
Bone Artifacts from Meadowcroft
Rockshelter
A good number of bone artifacts
were recovered at Meadowcroft. These were made from the bones of animals the
occupants killed for food. The awl far left has been grooved at one end to
accept a cord, so that it could be placed around the neck, ready for use in
sewing tasks.
Photo source : Meadowcroft a
pre-Clovis site15 (Original source Meadowcroft Rockshelter and
Historic Village Collection. Heinz History Centre).
A summary of the finds per
stratum were included in Adovasio’s table 21:
Note the reference to
Ash/Charcoal lenses (2) AND Lithic Concentrations (1) for stratum I
Later in the report Adovasio
produces a table (table 3) showing the radiocarbon dates obtained from the
Charcoal for most of the early (lower) strata:
The shocking part was that FIVE
of the radiocarbon ages pre-dated the accepted age for Clovis of about 11500BC!
At first reaction was muted, but as Adovasio continued to publish on
Meadowcroft7,8 serious objections began to be raised about the
site’s dating. The main objections raised were by Vance Haynes7 and
centred around the possible contamination of the charcoal samples
used to date the site by lignite or coal. Adovasio calmly and consistently
rebutted these claims of contamination9 and published greater deatil10.
However the attacks just kept on coming. Particularly prominent were the
criticisms by Dincauze (1981)11, Kelly (1987)12 and Tankersley,
Munson and Smith (1987)13 to name but three. In fact the situation
became so bad and relations within the archaeological community so fraught that
Adovasio coined the phrase ‘Clovis Mafia’ to describe those constantly making, what
he saw as, unwarranted and baseless criticisms. In 1990, Adovasio2 attempted to firmly and finally quash
the contamination, paleoenvironmental and stratigraphic issues raise by his
critics by publishing new AMS radiometric dates obtained by four different laboratories.
The dates are shown in his 1990 figure 1 below:
Original caption reads:
Plot of 52 Meadowcroft
Rockshelter radiocarbon dates showing one standard deviation. Four reversals
(asterisks) are noted: SI-2056 is actually from the lowest one-third of stratum
IIb; SI-2363 is from the upper one-third of stratum IV; SI-2363 is from the
upper one-third of stratum IX. Both SI-1681 and 2056 respectively were small
heavily diluted samples. Adapted and and expanded from Stuckenrath et al.
(1982: Figure 2).
Of particular note are that the
dates for the lowest stratum, stratum I are confirmed and retained.
Having dealt with the
stratigraphic and paleoenvironmental objections in separate publications16-18
he turned his attention to the contamination of the radiocarbon samples issue.
Adovasio has this to say:
“With regard to particulate contamination, we repeat that there is no
coal seam in or near the rockshelter. ..There are small, isolated,
discontinuous fragments of vitrinized Pennsylvania-age wood west of the back (north)
wall of the rockshelter, but these in situ fragments are circumscribed
occurrences and are not represented en bloc within 7m of the hearths that
produced the earlies Meadowcroft dates. ..Every radiometric sample from the
Pleistocene-age levels was examined for coal particles using both optical and
scanning-electron microscopy. No coal particles were ever identified by four
radiocarbon laboratories or by independent researchers.. We forcefully
reiterate that during these scrutinies, selected lower and middle stratum IIa
samples underwent not only reflectance analysis but also paleobotanical examination
for Densosporites and other commonly occurring spores of Pennsylvanian-age coal.
In all cases, the results were negative..”
Adovasio goes on, acidly, at
length about the absurdness of the claims of particulate coal contamination.
Given all he had put up with it is worth seeing what he had to say:
“For criticisms about particulate contamination (or stratigraphic perturbation)
to beto be credible, the mechanical introduction of vitrinized
Pennsylvanian-age wood into earlier Meadowcroft fire pits would have required
some unknown (and unspecified) mechanism so precise and of such duration that
it nevertheless resulted in consistent stratigraphic order among the early
dates. Then about 12,800 years ago, any mechanism that was making the early dates
too early would have to have discontinued so that all the successive younger
(more recent) dates were valid.. The absence ofany objective evidence for the
lack of particulate contamination and lack of any mechanism for the selective
injection of contaminants solely into the pre-12,800-year-old samples renders
the argument for particulate contamination unconvincing.”
In other words, to his critics “You
are making fools of yourselves making weak criticisms. Shut up!”.
With regard to non-particulate
contamination of the charcoal samples, Adovasio says this:
“1. Vitrinized wood cannot be dissolved in ground water..
2. If vitrinite is not the source of any dissolved contaminent, there
are no other candidates as the underlying shale (stratum I) that is the basal
unit is not carbonaceous.”
Here Adovasio is making a direct
jibe at Vance Haynes who famously kept a piece of vitrinized wood in a beaker
of water on his desk for months.. nothing happened!
Adovasio continues:
“3. Assuming the presence of an as-yet-undiscovered potential source of
contamination, there is no viable mechanism for its transport as the present
water table lies nearly 5m below the deepest occupation surface at the site and
it was never higher prehistorically..
4. Most basic to all questions of nonparticulate contamination is a
misreading of the available data..”
Adovasio explains his detractor’s
confusion to them. Tellingly, this matter is never raised again.
Adovasio disavows his earliest 32000 year old cultural materials
Now we come to an extremely
important passage regarding the charcoal with associated lithic assemblage,
dated to 32000 year ago, obtained from stratum I. Regarding this Adovasio says:
“The last, diminutive sample from the pre-cultural levels at the site was sent for processing in the
Oxford AMS system. The sample already had been scrutinized for particulates and
Densosporites spores, but the Oxford lab also examined it and detected no contaminants.
The solid fraction was extracted with no need to arrest the reaction and
subsequently date, as was the soluble fraction. The results for the solid
fraction was 31,400 +/- 1.200 years, 29450 BC (OxA-363). The soluble fraction
was dated at 30,900 +/- 1,100 years, 28,950 (OxA-364) (see Gillespie et al.
1985:241). These dates conform very closely to the previously calculated
Smithsonian lab date of 30,710 +/- 1,140 years 28,760 B.C. for this level,
which to repeat, is not associated with any artifacts and apparently dates to
well before the initial occupation of the site by humans (Adovasio 1975: 16,
Table 3).” See below for more on this issue.
Adovasio, then sets out his preferred
date for the site, rather tentatively, thus:
“The Meadowcroft dates suggest, rather conservatively, that humans were
present at the site perhaps 2,000-3,00 years earlier than the well-established
11,500-year horizon marker”
In other words: My site is proven pre-Clovis beyond reasonable doubt!
He continues:
“The frequently cited eighteenth millennium B>C> dates (SI-2060
and SI-2062) were both very small, diluted samples, one of which, SI-2060, has
a very high standard deviation of 2,400 years. If the younger range of both of
these dates is averaged, then the earliest possible occupation of the site may
have occurred ca. 16,770 years ago.”
This date has become the accepted
date for site. It seems that the weight of continued criticism had finally worn
Adovasio down. He was prepared to be conservative to silence his critics.
Unfortunately it wasn’t to be
criticisms were STILL raised throughout the 1990’s19.
It wasn’t until 1999 that an
independent study20 finally laid to rest the sceptics last shreds of
dissent. Meadowcroft WAS inhabited by pre-Clovis humans 16,770 years ago.
Dissent of a different kind
Mark McConaughy, a member of the
field crew that carried out the excavations during 1974 on the earliest levels
and who personally collected many of the samples that produced the earliest
dates has made some extremely persuasive comments to the effect that
Meadowcroft is most likely older than
current accepted age14.
Archaeologist Mark McConaughey
excavates on the Rockshelter’s east wall, July 1974.
Photo source : Meadowcroft a pre-Clovis site15 (Original source Meadowcroft Rockshelter and Historic
Village Collection. Heinz History Centre)
Here is what he had to say:
“The early radiocarbon dates from Meadowcroft have been criticized by
Haynes (1980, 1991), Kelly (1987), Mead (1980), Tankersley, Munson and Smith
(1987), Tankersley and Munson (1992) and others as being the result of various
types of coal contamination or incongruities concerning floral and faunal
associations. According to these people, either particulate coal or soluable
humates and carbon ions from coal percolated through the clays in ground water
at the shelter and were embedded in the charcoal collected and radiocarbon dated.
This contamination supposedly resulted in the samples producing anomalous
dates. These criticisms have also been addressed by Adovasio et al. (1980),
Adovasio, Donahue and Stuckenrath (1990) and Adovasio, Donahue and Stuckenrath
(1992). Generally, they disagree with the view that coal contamination of the
samples resulted in dates that are too old or that the floral and faunal
associations do not indicate a Pleistocene occupation at the site.
I personally do not believe any of the radiocarbon dates from the early
levels at Meadowcroft are erroneous. I think they properly date the samples
submitted and are not contaminated by coal. However, I am hardly an unbiased
observer.
The earliest remains from Meadowcroft did not come from excavations
within the drip-line of the rockshelter. Most came from an area excavated
beside the Old Roof Fall (an immense rock that fell from the top of the shelter
prior to anyone living at the site).
Two samples I recovered were dated to ca. 19,000 years ago.
Unfortunately, the two 19,000 B.P. samples were not directly associated with
stone tools. ..It is for this reason that the bark was only tentatively
identified as a basket fragment in Meadowcroft reports, and the dates
questioned as being associated with a Paleoindian occupation.”
With regard to the very
oldest materials recovered from stratum I McConaughy says this:
“Most other charcoal samples taken and dated from the earliest levels,
(and dated as 33000 years old) or the "Deep Hole" as it was named by
the crew, consisted of pieces of charcoal found with ash and burned earth.
These were interpreted as surface hearths that had been put out (i.e., kicked
out, spreading some of the ash and charcoal around). Stone tools were found in
association with these samples lending support to the interpretation of them
being extinguished hearths.”
This directly contradicts
Adovasio 1990, but is supported by Adovasio 1975. One can only, therefore,
conclude that Meadowcroft is probably older than ca. 16,000 years old as
currently quoted and most probably 33000
years old.
One can only assume that Adovasio
chose in 1990 to take the road more travelled by at last, just to get
Meadowcroft within the mainstream of accepted sites.
One final thought from Adovasio
19751: Stratum I consists of badly decomposed, foliated sandstones
(possibly roof fall?) - perhaps this indicates that the bedrock was not
actually reached and further unexcavated levels remain below…
References
1. Excavations at Meadowcroft Rockshelter, 1973-1974: A
Progress Report
By J. M. Adovasio, J. D. Gunn, J. Donahue, and R.
Stuckenrath
1975. Archaeologist 45(3), pp.1-30.
2. The
Meadowcroft Rockshelter Radiocarbon Chronology 1975-1990
J. M. Adovasio,
J. Donahue and R. Stuckenrath
American
Antiquity Vol. 55, No. 2
(Apr., 1990), pp. 348-354
4. Quoted in Tom Imerito
Pittsburgh Quarterly Fall 2012 online
“Ancient dig discovering man in America: Archaeological
finds at Meadowcroft Rockshelter turned back the clock on humankind’s first
migration to the new world
5. In Albert Miller: Renaissance Man April 27, 2015 by Mark Kelly
6. The First Americans: In Pursuit of Archaeology's Greatest
Mystery
by James M. Adovasio with
Jake Page. 2002. Random House.
7. Haynes, C. V.1980 Paleoindian Charcoal from Meadowcroft
Rockshelter: Is Contamination a Problem? American Antiquity 45:582-587.
8. Mead, J. I. 1980 Is It Really that Old? A Comment about
the Meadowcroft Rockshelter "Overview." American Antiquity
45:579-582.
9. Adovasio, J. M., J. D. Gunn, J. Donahue, R. Stuckenrath,
J. E. Guilday and K. Volman1980 Yes Virginia, It Really is that Old: a Reply to
Haynes and Mead.
American Antiquity 45:588-595.
10. Carlisle, R. C. and J. M. Adovasio, eds. 1982.
Meadowcroft: Collected Papers on the Archaeology of Meadowcroft Rockshelter and
the Cross Creek Drainage. Department of Anthropology, University of Pittsburgh,
Pittsburgh.
11. Dincauze D. F 1981. The Meadowcroft Papers. Quarterly Review of Archaeology :3-4
12. Kelly, R.L. 1987 A Comment on Pre-Clovis Deposits at
Meadowcroft Rockshelter. QuaternaryResearch 27:332-334
13. Tankersley, K. B., C. A. Munson and D. Smith. 1987
Recognition of Bituminous Coal Contaminants in Radiocarbon Samples. American
Antiquity 52:318-330.
14. Mark McConaughy. Retrieved from:
16. Meadowcroft Rockshelter: A 16000 Year Chronicle. In Amerinds and Their Paleoenvironments in
Northeastern North America, edited by W. S. Newman and B. Salwen, pp.
137-159. Annals of the New York Academy of Sciences 288. New York.
17. Adovasio et al. 1984. Meadowcroft Rockshelter and the
Pleistocene/Holocene Transition in Southwestern Pennsylvania. In Contributions in Quaternary Vertebrate
Paleontology: A Volume in Memorial to John E. Guilday, edited by H.H.
Genoways and M. R. Dawson pp. 347-369. Special Publications No. 8. Carnegie
Museum of Natural History, Pittsburg.
18. Adovasio et al. 1985 Paleoenvironmental Reconstruction
at Meadowcroft Rockshelter, Washington County, Pennsylvania. In Environments and Extinctions: Man in Late
Glacial North America edited by J. I. Mead and D. J. Meltzer, pp 73-110.
Peopling of the Americas Edited Volume Series, Centre for the Study of Early
Man, Orono, Maine.
19. Tankersley, K. B. and C. A. Munson 1993 .Comments on the
Meadowcroft Rockshelter Radiocarbon Chronology and the Recognition of Coal
Contaminants. American Antiquity 57: 321-326.
20. Goldberg, P and Arpin, T. L. 1999. Micromorphological
Analysis of Sediments from Meadowcroft Rockshelter, Pennsylvania: Implications
for Radiocarbon Dating
Journal of Field Archaeology Vol. 26, No. 3
(Autumn, 1999), pp. 325-342
