Research Article
The U.P. Mammoth Site, Carbon County, Wyoming, USA: More
Questions than Answers
C. Vance Haynes Jr.,1 Todd A. Surovell,2 ,* and Gregory W. L. Hodgins3
1
School of Anthropology, University of Arizona, Tucson, Arizona
Department of Anthropology, University of Wyoming, Laramie, Wyoming
3
NSF-Arizona, AMS Facility, Department of Physics, University of Arizona, Tucson, Arizona
2
Correspondence
*Corresponding author;
E-mail: [email protected]
Received
20 June 2012
Accepted
11 December 2012
Scientific editing by Gary Huckleberry
Published online in Wiley Online Library
(wileyonlinelibrary.com).
doi 10.1002/gea.21433
In the summer of 1960, mammoth bones were discovered by a dragline operator in southern Wyoming at the Union Pacific (U.P.) Mammoth site. Although
subsequent archaeological work during 1960 and 1961 identified artifacts in
association with the mammoth remains, many authors have since questioned
the nature of that association. Also, little has been published about the site
other than a brief article in National Geographic Magazine in 1962. In this paper, we present additional information on the U.P. Mammoth site including
stratigraphic profiles from the first author’s geoarchaeological work in 1961,
stratigraphic and spatial location of bones and artifacts derived from the original field notes, and new radiocarbon dates. Although the precise stratigraphic
provenance for many artifacts and skeletal elements remains unclear, a compelling argument can be made for spatial and stratigraphic association of the
mammoth remains with the artifact assemblage suggesting some kind of huC 2013 Wiley Periodicals, Inc.
man interaction with the animal. INTRODUCTION
At the Union Pacific (U.P.) Mammoth site, artifacts were
discovered in association with the remains of Columbian
mammoth (Mammuthus columbi), and although the initial
report on the site suggests that its investigators had little
doubt about the meaning of that association (Irwin,
Irwin, & Agogino, 1962; Irwin, 1970), others who have
examined the evidence since are less certain. On the
basis of the artifacts that were discovered, patterns
of bone modification, and the spatial arrangement of
skeletal elements, Irwin et al. (1962) interpreted the
site to represent a kill and butchery event. Citing Frison
(1978:29, 85), Grayson and Meltzer (2002:323) refer
to the association of artifacts and mammoth remains
at U.P. as “tenuous or nonexistent.” Frison (1978:29)
suggests that some of the artifacts were recovered from
“questionable contexts” and was unable to examine all of
the skeletal remains recovered to verify the presence of
human modification. Frison (1978), G. Haynes (1991),
and Cannon and Meltzer (2004) all have lamented that
the results of the investigations at the site were never
fully published. In that light we here present additional
information on both the stratigraphic and spatial associ-
Geoarchaeology: An International Journal 28 (2013) 99–111
ation between the artifacts and mammoth remains that,
along with new radiocarbon dates, provides additional
data relevant to the hypothesis of cultural association.
In the summer of 1960, the first author was called to
the University of Wyoming by Anthropology Professor
George A. Agogino for the purpose of examining and
hopefully dating the skeleton of a mammoth that had
been uncovered at Sage Chicken Spring about 50 km
southwest of Rawlins, Wyoming (Figure 1). The bones
were exposed in August by Mr. Ivan Hays while deepening the spring with a dragline in order to increase water
flow for a nearby drilling project. A few days later a large
black bifacially flaked knife was found at the site in uncertain association. Dr. Brainerd Mears, a geomorphologist from the University of Wyoming, who was assisting
in the initial excavations, claims the artifact was found on
the surface (George C. Frison, personal communication,
2011). It is made of “tiger chert” from western Wyoming.
The following year a large yellowish brown jasper bifacial
knife was recovered from near the axis vertebra, along
with many less spectacular stone tools from the excavated
areas.
Because Agogino did not like calling the mammoth site
the Chicken Springs site, he decided to name it the U.P.
C 2013 Wiley Periodicals, Inc.
Copyright 99
THE U.P. MAMMOTH SITE, CARBON COUNTY, WYOMING, USA
HAYNES ET AL.
Figure 1 Location map for the U.P. Mammoth site, Carbon County, Wyoming.
Mammoth site, mistakenly believing it was on their property or lease. It is here shortened to the U.P. site, but a
new name is called for as explained later.
Formal excavations by crews from Harvard University
under the direction of Henry and Cynthia Irwin (brother
and sister) and from the University of Wyoming under
the direction of George Agogino were conducted during
the summer of 1961, with support of the National Geographic Society (Irwin, Irwin, & Agogino, 1962). The first
author was the project geologist. An 80 ft × 50 ft (48 m ×
15 m) area was laid out by the archaeologists at 45◦ to
the cardinal directions and divided into a grid with 5-ft
(1.53 m) squares (Figure 2). Five 5-ft-wide trenches, perpendicular to the local drainage, were extended 20 ft
(6.1 m) to the southwest from the bone and artifact concentration leaving 5-ft-wide balks between trenches, thus
providing three-dimensional exposures of much of the
stratigraphy that was subdivided into eight stratigraphic
units (Figures 3 and 4; Table I). Table II is a correlation
chart of stratigraphic designations of Table I with those of
the archaeologists.
100
Stratigraphic relationships as revealed by excavations
are shown in Figures 5 through 7. Bedrock sandstone,
coal, and shale of the Tertiary Lance Creek Formation
dip 5◦ –10◦ northwest. A coal bed at the site is the local aquifer, and its intersection with the draw produces
the spring seepage that today maintains a wet meadow
or cienega.
STRATIGRAPHY
Six stratigraphic units (A–F and subdivisions thereof)
were identified in the excavations. The strata and their
subdivisions were based on sediment type and color
as well as weathering criteria (soil development and
groundwater alterations). The paleosols developed on
Strata D, C, and A are truncated by erosion, and, therefore, are incomplete (Table I).
Stratum A is composed of clay and coal sand apparently flushed from the coal and shale beds by spring
discharge during a period of vigorous spring activity.
C 2013 Wiley Periodicals, Inc.
Geoarchaeology: An International Journal 28 (2013) 99–111 Copyright Figure 2 Geologic excavation map of the U.P. Mammoth site showing the location of the skeleton with respect to bones and artifacts with adequate provenience for plotting. Grid units are identified by
number in the NW-SE direction and letters in the NE-SW direction. In 1961, controlled excavations were initially in trenches A, E, G, I, and K. Excavations were later that year expanded to the other trenches
shown by circled letters.
HAYNES ET AL.
Geoarchaeology: An International Journal 28 (2013) 99–111
THE U.P. MAMMOTH SITE, CARBON COUNTY, WYOMING, USA
C 2013 Wiley Periodicals, Inc.
Copyright 101
THE U.P. MAMMOTH SITE, CARBON COUNTY, WYOMING, USA
HAYNES ET AL.
Figure 3 Generalized stratigraphic cross-section of the valley of Chicken Spring Creek at the U.P. Mammoth site (no scale but vertically exaggerated).
See Table I for descriptions of strata designated by letters A, B, C, D, E, and F.
Several ancient spring feeders in the form of vertical tapered conical conduits filled with white quartz sand were
exposed during the excavations. These are extinct examples of the active feeders encountered during the excavations in which sand is kept in suspension and sorted by
the roiling action of ascending water (Haynes, 2008a).
The truncated soil developed on upper Stratum A
(Table I) reflects diminished spring activity and deposition of iron from the capillary fringe of a declining water
table and eventually under subaerial but very moist soil
conditions. The erosional surface on Stratum A, which
truncates one of the feeders just mentioned (Figure 5,
Trench G1 ), probably reflects further lessening of spring
seepage.
Accumulation of Stratum B, a relatively thin layer of
calcareous sinter (marl) and tufa, suggests intermittent
wetting and drying of the ground around the spring. The
marl indicates standing water at times, and the fibrous
masses of tufa that occur on the northeast side of the
valley (Figure 6) are probably the result of algal activity
when the water table was emergent as seeps.
The absence of weathering profiles between the channel fills of Strata C1 and C2 (Table I) indicates that they
represent two fluvial cut-and-fill episodes separated by
time that was inadequate for pedogenesis. Stratum C3
is a combination of alluvial, spring, and slopewash sediments that buried C1 and C2 with little evidence of soil
development until after deposition. The relatively strong
paleosol developed on Stratum C3 shows, in the lower areas, gleization of iron and manganese and subsequent displacement of these elements by strong calcification. This
probably required a significant period of time before deposition of Stratum D. This and the truncation of the C
strata by erosion indicate a considerable hiatus exists between deposition of Strata C and D.
102
Figure 4 Stratigraphic column for the U.P. Mammoth site showing radiocarbon dates and the positions of artifacts and bones. Roman numeral
designations are those of the archaeologists (see Table II). Calibrations are
from IntCal09 (Reimer et al., 2009) and OxCal version 4.1.7 (Bronk Ramsey,
2009).
The fluvial nature of Stratum C suggests that the
drainage was receiving more flashy runoff than that indicated by either Stratum A or Stratum B. Stratum D indicates renewed runoff after the period of soil development
C 2013 Wiley Periodicals, Inc.
Geoarchaeology: An International Journal 28 (2013) 99–111 Copyright THE U.P. MAMMOTH SITE, CARBON COUNTY, WYOMING, USA
HAYNES ET AL.
Table I Stratigraphic descriptions at the U.P. Mammoth site.
Stratuma
F
E (I)
D3 (II)
D2 (II)
D1 (II)
C3 (III)
C2 (IIIa)
C1 (IIIb)
B (IVa)
A2a -A2b (IVb)
A1 (IVb)
Bedrock
Descriptionsb,c
Sand—Yellowish brown, unsorted, clayey, gravelly sand deposit derived from efforts of ranchers to excavate
and dam the spring. Sediments contained a brass, caliber 30–30 cartridge case, rusted tin cans, and other
recent debris. Also includes sediments disturbed by the dragline operation. No colors given because of the
artificially mixed nature of the deposit, but generally it is shades of yellowish brown.
Sand—Grayish brown (10YR 5/2, 3/3), poorly sorted, silty clayey sand alluvium with dispersed grit and
carbonate films in rootlet molds; moderate to weak, medium to coarse blocky soil structure in the upper half.
Weak effervescence with HCl in upper half and moderate to strong effervescence in lower half. Loose to soft
consistence when dry. Upper contact is the ground surface but the stratum is truncated by the valley walls.
Sand—Grayish brown (2.5Y 5/2, 3/2), clayey, silty sand alluvium with strong, fine to medium platy structure.
Sharp erosional upper contact.
Sand—Light gray (10YR 7/1, 4/1) clayey silty sand alluvium with strong-medium angular blocky structure with
hydrated iron and manganese oxide-stained ped surfaces. Numerous soft impregnations of calcium
carbonate clay around rootlet molds and as blotches. Upper contact is gradational.
Sand—Gray (5YR 6/1, 3/1) calcareous clayey silty sand alluvium with weak to moderate angular blocky structure
and hydrated iron and manganese oxide-stained ped surfaces. Small gastropod shells are dispersed in this
stratum. Upper contact is gradational. Late Archaic artifacts were reportedly found in the base of this stratum.
Sand—Gray (2.5YR 6/1, 10YR 3/1, upper half, 5Y 6/1, 3/1, lower half), calcareous clayey, silty sand alluvium with
strong, medium to coarse, prismatic structure. Carbonate-coated rootlet molds, carbonate impregnations,
and weak hydrated iron oxide (rust colored) stains on ped surfaces. Strong HCl reaction. Sharp erosional
upper contact.
Sand—Gray (10YR 5/1, 5Y 2/1), calcareous silty clayey sand alluvium with numerous dispersed fine to medium
sand-sized coal grains. Moderate to strong, coarse prismatic structure. Pedogenic features are an extension
from the paleosol on Stratum C3 . Contains bones of extinct mammals and artifacts. Moderate to strong HC1
reaction and weak hydrated iron oxide stains on a few ped surfaces. Gradational upper contact removed in
places by mechanical equipment.
Gravel—Orange-red, poorly sorted, gritty, medium-pebble, sandy, angular to platy, gravel channel fill
containing bones of extinct mammals and artifacts. Sharp erosional upper contact.
Marl—White (2.5Y 8/2, 5/2), silty, chalky, calcareous sinter; sandy clay; rudely laminated white, gray, and black
calcareous coarse, silty sand, all laterally gradational. Upper third in a few places on the northeast side of the
draw contains calcareous iron-stained tufa masses resembling replaced or coated moss. Very strong HC1
reaction. Stratum B is truncated by the Strata C1 and C2 channel deposits. Sharp erosional upper contact.
Sand—A2a very dark grayish brown (10YR 3/2, 3/1) clayey, fine to medium sand alluvium gradational laterally to
A2b as rudely laminated gray, white, and orange clayey silt and sand slopewash alluvium interbedded with
coarse coal sand. This truncated paleosol has moderate to strong coarse prismatic structure with strong
limonite impregnations and films (oxidized gleying) on ped surfaces and rootlet molds. Sharp erosional
contact truncates sand-filled spring feeders (A3 ).
Sand—A1 black (5YR 2/2) fine to medium coal and quartz sand alluvium. No HCl reaction and no root molds or
structure. Upper contact gradational.
Laminated coal and black shale of the Lance Creek Formation of Tertiary age. Contact with Stratum A marked by
up to 6 in. of coal and shale rubble.
Maximum thicknessd
5
(1.52)
2.5
(0.76)
2
(0.60)
2
(0.60)
2
(0.60)
2
(0.60)
5
(1.52)
4
(1.22)
1.5
(0.46)
2
(0.60)
4
(1.22)
2+
(0.60+)
a
Roman numerals (in parentheses) are crew designations.
Sedimentary descriptions are taken from the 1981 field notes of the first author.
c
Munsell colors are given in dry and wet conditions.
d
Maximum observed thickness in feet and (meters).
b
in C and its subsequent erosion. Stratum D is less sorted
and contains more sand and silt than does Stratum C. This
suggests a larger content of slopewash sediment in D than
in C. A channel facies of Stratum D, if ever present, was
not observed, probably because of removal by either erosion or excavation by ranchers during their modifications
of the spring.
The soil developed on Stratum D (Table I) indicates that
a time gap exists between Strata D and E during which
Geoarchaeology: An International Journal 28 (2013) 99–111
iron and manganese precipitation was followed by calcification. The weathering profile in D was only slightly
affected by erosion before deposition of Stratum E, which
constitutes a modern soil that is apparently being eroded
today. The poor sorting of Stratum E suggests deposition
predominantly via slopewash.
As related by old-time residents of the area, an attempt
was made in the early 1900s to dam the draw by excavation and filling, but the dam was washed out a few
C 2013 Wiley Periodicals, Inc.
Copyright 103
THE U.P. MAMMOTH SITE, CARBON COUNTY, WYOMING, USA
years after its completion. Stratum F, with historic artifacts and sharp, straight, artificial contacts, is probably
derived from these activities, as well as from the dragline
excavations that exposed the mammoth bones.
PALEOCLIMATIC INTERPRETATION
Without more evidence, climatic interpretations of sediments are at best tenuous. Multiple small spring feeders
and flame structure in Stratum A represents the period of
most intense spring flow in evidence at the site. This was
apparently due to a greater supply of water to the coalbed aquifer than has occurred since. The truncated paleosol developed in upper Stratum A indicates a hiatus in
deposition followed by desiccation indicated by oxidized
gleying (Table I) before deposition of Stratum B with renewed spring discharge. The marl and tufa of Stratum B
reflect local ponding of spring discharge. Stratum C indicates fluvial conditions of cutting and filling during a period of increased precipitation and flashy fluvial discharge
relative to the period represented by Stratum B and the
soil in Stratum A. The activity of the spring after the deposition of Stratum B is not apparent in the stratigraphic
record, but it can be reasoned that a marked increase in
spring discharge would aid stream flow in flushing sediments from the ravine during periods of intense runoff.
This may have been the cause of the cutting indicated by
the basal contacts of Strata C1 and C2 . Each could represent a single storm event.
The soil in Stratum C3 clearly reflects a trend
toward drier conditions when subaerial weathering
produced first gleization and subsequently calcification
prior to erosion. The channel facies of Stratum D are not
present, probably due to the artificial excavations mentioned previously, but the slope facies again reflect fluvial
conditions similar to those suggested by Stratum C, except perhaps with more contribution from slopewash.
The greater thickness of Stratum D may indicate a longer
time for deposition of Stratum D than Stratum C. Stratum E appears to be principally the result of slopewash
sedimentation and soil development immediately prior to
or penecontemporaneous with ranching in the area.
STRATIGRAPHIC PROVENANCE OF THE
MAMMOTH SKELETON
At the time the first author first visited the U.P. site
in August 1960 most of the bones of the mammoth
skeleton had been removed from their location under
water and transported to Rawlins. No effort to profile
strata was attempted until the following year after the
local water table had been lowered by around-the-clock
104
HAYNES ET AL.
Table II Correlation chart of stratigraphic designations at the U.P.
Mammoth site.
Geologicala
Archaeologicalb
E
D
C3
C2
I=1
II = 2
III = 3
IIIa = IIIA = 3a = 3A
C1
IIIb = IIIB = 3b = 3A
B
IVa = IVA = 4a = 4A
A
IVb = IVB = 4b = 4B
Crew descriptionsc
“Light gray”
“Gray clay”
“Arroyo clay (gray)”
“Mud with large clastic
fragments”
“Gravel in gray clay”
“Gravel”
“Arroyo gravel (orange)”
“Gray clay & buff sand”
“White clay”
“White Bentonite laminates”
“Black”
“Black swamp”
“Black sand with white sand
inclusions”
“Black-fine-coarse coal”
“Black muck”
a
Letter designation of geological strata are from the bottom up reflecting
the geochronological sequence of deposition.
b
Archaeological strata are numbered from the top down, that is, in the
order of excavation.
c
Sediment designations and descriptions were gleaned from field notes.
pumping, which failed at times. A 4400 ft2 (409 m2 )
area was laid out in 5-ft squares at 45◦ to the cardinal
directions in order to parallel the drainage (Figure 2)
and provide cross-sections perpendicular to the drainage
(Figures 5 through 7).
The precise stratigraphic position of the mammoth
skeleton was not determined in 1960 because the water
table obscured the host strata. Agogino (personal communication, 1960) told the first author that the mammoth bones were found in “black muck” about 6 ft below
the valley floor. Therefore, there is uncertainty regarding the stratigraphic provenance of the intact mammoth
skeleton because there was no stratigraphy recorded during the removal of most of the large bones.
Stratum A is, for the most part, black coal sand
(Table I). A photograph taken in 1960 by a public relations photographer of the U.P. Railroad shows
Agogino pointing out a gray stratum overlying Stratum A
(Figure 8). A notation on the back states “Dr. Agogino
pointing to chips in excavation wall . . . ” “the black muck
below is . . . where the mammoth bones and Clovis point
were found.” The caption writer probably received this
information from Dr. Agogino, and the Clovis designation was later dropped by Agogino. The photograph illustrates the southwest wall of the excavation in the
early stage of controlled excavation of trenches and is
most likely the I-Line of the grid of 5-ft squares at the
C 2013 Wiley Periodicals, Inc.
Geoarchaeology: An International Journal 28 (2013) 99–111 Copyright THE U.P. MAMMOTH SITE, CARBON COUNTY, WYOMING, USA
HAYNES ET AL.
northeast end of the baulk between Lines 9 and 10 (Figure 2). Other photographs, apparently by the same photographer, show trenches of an incipient stage of excavation. The baulk where Agogino is pointing out a cultural
layer is probably that between Trenches G and I in which
case the gray layer is Stratum B over Stratum A (Figure
7b). A complete coyote skeleton shown in several of the
photographs (Figure 8) is on Stratum C3. It was probably in Stratum E or Stratum F in which historic artifacts
were also found. It was removed early in the excavations
such that the overlying strata were absent at the time of
profiling.
Descriptions of the strata are rare and sparse in the
field notes. Table II shows the probable correlations of the
crew members’ designations to those of the first author.
Stratigraphic profiles by crew members in 1961 (Irwin &
Irwin, 1961:162) also indicate that the “black muck” is
Stratum A. Unfortunately, of nine bone fragments shown
in the original field notes as being from Stratum A, only
one is specifically attributed to mammoth. However, from
Agogino’s statement and from newspaper statements of
others, it appears that the mammoth skeleton probably
came from Stratum A.
Now the question that arises is: was the mammoth incorporated in Stratum A as it formed or did it sink into
it after it was deposited? The opinion of Agogino and
the Irwins is that the mammoth had become stuck in
the black muck and either died as a result or was killed
by humans (Agogino, Irwin, & Irwin, 1962). As will be
seen in the following discussion of the provenances of
other bones as well as the artifacts, a case can be made
for the mammoth being contemporary with the contact between Stratum B and Stratum A, that is, the B/A
contact.
Most of the mammoth bones away from the skeleton
were in Strata C1 and C2 and were upstream of the carcass.
There are three possibilities: (1) they were moved there
by Archaic people, (2) late Pleistocene people moved
some of the mammoth bone upstream during processing that subsequently got redeposited during deposition
of Stratum C1, and (3) there is another mammoth skeleton upstream. Unfortunately, to our knowledge, there is
no bone inventory to tell if there are duplicates, that is,
two of the same element such as the axis vertebrae. If
there is any duplication of elements it was, to our knowledge, not recorded.
STRATIGRAPHIC PROVENANCE OF BONES
AND ARTIFACTS
From the field notes it appears that at least 67 bones or
bone fragments dispersed away from the skeleton were
Geoarchaeology: An International Journal 28 (2013) 99–111
Table III Bone distributions by stratum at the U.P. Mammoth site.
No.a
Mammoth bones in
Stratum A
Unidentified bones in
Stratum A
Totals
Percentb
1
1.49
14
20.90
15
Percentc
22.39
Mammoth bones in
Stratum B (B/A contact)
Unidentified bones in
Stratum B (B/A contact)
1
1.49
2
2.99
Mammoth bones in
Stratum C1
Unidentified bones in
Stratum C1
2
2.99
9
13.43
Mammoth bones in
Stratum C2
Unidentified bones in
Stratum C2
8
3
4.48
11
16.42
11.94
0
8
Bones in indeterminate
stratum
30
Total bones identified as
mammoth
Total bones unidentified
Total bones recorded
12
11.94
44.78
30
44.78
17.91
55
82.09
67
100.00
a
Numbers derived from field notes and separating those specified as mammoth from those unspecified.
b
Percentages of those specified as mammoth and those not specified.
Many of the latter are probably mammoth.
c
Percentages of totals of both categories.
recovered (Table III). Of these only 12 (17.9%) were
recorded as mammoth. Most were upstream (southeast)
of the mammoth skeleton (Figure 2) and in Stratum
C2 (11.91%) or Stratum C1 (2.99%) (Table III). Only
one (1.49%) was in Stratum A and one (1.49%) was in
Stratum B, on the B/A contact. If most of the 55 unidentified bones are also mammoth bones, as seems likely, 14
(20.10%) are from Stratum A, two (2.99%) were on the
B/A contact, nine (13.43%) were from Stratum C1, and
Stratum C2 had none. All but one of the bones in Stratum
B were actually on the B/A contact.
The axis vertebra of a mammoth was recovered in Stratum C1 about 8 in. (20 cm) above a large yellowish brown
jasper ovoid bifacial artifact (#115). The biface was also in
Stratum C1 and about 18 in. (46 cm) northeast of the axis
vertebra (Figure 5, Trench G1 ). A large rock about 12 in.
× 6 in. (∼30 × 15 cm) found about 5 ft (∼1.5 m) south of
the axis vertebra is anomalously larger than other clasts
in Stratum C1 gravel.
C 2013 Wiley Periodicals, Inc.
Copyright 105
THE U.P. MAMMOTH SITE, CARBON COUNTY, WYOMING, USA
HAYNES ET AL.
Figure 5 Stratigraphic profiles by the first author of walls of trenches C1 , E1 , G1 , I, and K and map of square J8, 1961.
What was referred to early in the 1960 investigations
as a longitudinally broken Clovis point is actually a bifacially flaked edge of what is probably better described
as a backed knife of “tiger chert,” a silicified shale of
106
the Tertiary Green River Formation from about 160 km
west of Sage Chicken spring. The specimen was reported
by Agogino (personal communication, 1960) as brought
up from under water in a shovel full of “black muck.”
C 2013 Wiley Periodicals, Inc.
Geoarchaeology: An International Journal 28 (2013) 99–111 Copyright THE U.P. MAMMOTH SITE, CARBON COUNTY, WYOMING, USA
HAYNES ET AL.
Figure 6 Stratigraphic profiles of walls of trenches C2 and E and extensions thereof to valley walls cut by mechanical equipment as plotted by the first
author in 1961.
However, as mentioned earlier, its precise stratigraphic
position cannot be determined. Its location on Figure
2 is shown by an X within a dashed circle to show
what may be its approximate location. This and the location of the intact mammoth in Figure 2 is shown
by a sketch in an excavation map in Irwin and Irwin
(1961). We added artifacts, bones, and other items af-
ter studying the field notes for items with adequate
provenance.
Of the 29 stratigraphically documented artifacts, only
one (3.4%) is from Stratum C2, 41.4% are from Stratum
C1 , 34.5% are from Stratum B (mostly the B/A contact),
and 20.7% are from Stratum A (Table IV). Of the total
of 71 artifacts 42 (59.1%) are, unfortunately, from strata
Figure 7 Stratigraphic profiles of the walls of excavations at the back wall made by mechanical equipment and the I-Line plotted by archaeological crew
members, 1961.
Geoarchaeology: An International Journal 28 (2013) 99–111
C 2013 Wiley Periodicals, Inc.
Copyright 107
THE U.P. MAMMOTH SITE, CARBON COUNTY, WYOMING, USA
HAYNES ET AL.
Figure 8 Union Pacific Railroad photograph of the U.P. Mammoth site excavations in 1960 showing George Agogino pointing out a bed with artifacts in
Stratum B (light gray) and Kay Irwin (mother of Cynthia and Henry) excavating a coyote skeleton on Stratum C3 (dark gray). Stratum A is the black layer
below Stratum B.
that were not recorded. From these data and the bone
stratigraphic provenance we believe the mammoth and
some of the artifacts are probably contemporary with the
B/A contact. However, a significant number of mammoth
bones were removed to or redeposited to Strata C1 and
C2 .
In the draft of an unpublished report Agogino and
the Irwins considered the bones and artifacts upstream
of the mammoth carcass to have been placed on an
108
upstream “gravel bar” by the people who either killed
or scavenged the mammoth (Agogino, Irwin, & Irwin
1962). However, it is clear now that the “gravel bar” is
Stratum C1 which postdates Strata A and B, in which
case a later band of people interacted with the mammoth
skeleton as well as an earlier band contemporary with
the B/A contact. The earlier band may have moved bones
upstream that later got redeposited in Stratum C. The
earlier band could be Clovis because artifacts typical of
C 2013 Wiley Periodicals, Inc.
Geoarchaeology: An International Journal 28 (2013) 99–111 Copyright THE U.P. MAMMOTH SITE, CARBON COUNTY, WYOMING, USA
HAYNES ET AL.
Table IV Artifact distributions by stratum at the U.P. Mammoth site.
Stratum A
Stratum B (nine are on B/A contact)
Stratum C1
Stratum C2
Stratum C3
Subtotal
Stratum not specified
Total
No.a
Percentb
Percentc
6
10
12
1
0
29
42
71
20.7
34.5
41.4
3.4
8.5
14.11
16.9
1.4
100.0
59.1
100.0
a
Numbers derived from field notes and descriptions.
Percentages excluding strata not specified.
c
Percentages including strata not specified.
b
Clovis, though non-diagnostic, have been found on the
surface (Prasciunas et al., 2012).
RADIOCARBON DATING
The abundance of silt and sand-sized coal in Stratum A
resting directly on a coal bed in the Tertiary Lance Creek
Formation was cause for concern about contamination of
samples collected at the site for 14 C dating. However, unlike 14 C dates from the lower strata of Meadowcroft Rockshelter in a coal mining region of Pennsylvania (Haynes,
1991a), none of the U.P. site 14 C dates are on organic
residues or soluble organic matter. The tusk ivory that
provided the first 14 C date was clean, ivory color, and
tenacious enough that it would be suitable for the manufacture of piano keys. Except for the ∼0.5-mm-thick surface layer, there was no brown staining as could be expected from absorption of soluble humic matter. Furthermore, the chemical pretreatment to which the recently
collected ivory sample was subjected by the third author
produced a very clean, high purity collagen. All ivory 14 C
dates, ours and that of Isotopes, Inc., are well within one
sigma as shown in Table V.
The first, and for many years, the only 14 C date for
the U.P. mammoth was one on ivory from a tusk as just
mentioned. The sample was pretreated by the first author following a procedure used by May (1955) of the
U.S. Geological Survey, whereby the sample was charred
by pyrolysis in an electric furnace followed by hydrolysis
in hydrochloric acid. The resulting black carbon residue
was sent to Milton Trautman of Isotopes, Inc. for combustion to CO2 and measurement in their gas proportional
counter by Charles Tucek (Trautman & Willis, 1966). Soluble humates would not have been removed by this treatment. The result is an age of 11,280 ± 350 14 C year B.P.
(I-449). All radiocarbon dates, both calibrated and uncalibrated, are shown in Table V and Figure 4. Calibrations
used the IntCal09 database (Reimer et al., 2009) and OxCal Version 4.1.7 (Bronk Ramsey, 2009).
In 2009, the second author resampled a tusk of the
U.P. mammoth on display in the Geology Museum of
the University of Wyoming. Using a 5/16 in (79 mm) inside diameter diamond core bit, he removed three samples weighing 0.35 g, 0.5 g, and 1.1 g from the lateral
surface of the left tusk. Two of these were processed by
the third author. The first aliquot of tusk dentin was extracted using a Soxhlet apparatus with solvent series hexane, ethanol, methanol, and water. After drying, it was
crushed to <1 mm particles and subjected to acid, base,
acid extraction using an automated continuous flow extraction system. The material was gelatinized at 70◦ C,
passed through a 12-μm filter, and then lyophilized. Collagen yields for the two samples were 20.1% and 19.0%
of the starting mass of tusk dentin, respectively, corroborating the visual assessment of fine preservation. A second aliquot was treated like the first but with an additional step of ultrafiltration (Bronk Ramsey et al., 2004).
Collagen from each sample was split, one processed directly for AMS measurement and the other after ultrafiltration. Each split was run twice by the NSF-Arizona
AMS Laboratory, producing four numbers that were averaged for a date of 11,560 ± 6014 C year B.P (Figure 4
and Table V).
Two wood samples collected from the site were subjected to the standard acid-base-acid pretreatment for
Table V Radiocarbon dates from the Union Pacific Mammoth site.
Lab no.
Material
AA-87742
Bone collagen
AA-86461
Sarcobatus wood
I-474
Wood fragments
I-449
Tusk organic matter
AA-84864
Tusk collagen
AA-84865
Tusk collagen
AA-100399
Tusk collagen
AA-100400
Tusk collagen
Avg. of four tusk collagen
Geoarchaeology: An International Journal 28 (2013) 99–111
Stratum
δ13 C %
14
E or F
C1 or C2
C1
B/A
B/A
B/A
B/A
B/A
−16.6
−27.6
n/a
n/a
−20.4
−20.3
−20.5
−20.6
289 ± 32
3838 ± 97
4975 ± 180
11,289 ± 350
11,562 ± 88
11,596 ± 88
11,507 ± 116
11,547 ± 117
11,560 ± 60
C 2013 Wiley Periodicals, Inc.
Copyright C age ± σ (14 C year B.P.)
Cal. year B.P. (95.4% CI)
460–290
4520–3970
6180–5320
13,900–12,530
13,660–13,240
13,680–13,270
13,640–13,140
13,690–13,175
13,590–13,270
109
THE U.P. MAMMOTH SITE, CARBON COUNTY, WYOMING, USA
the purpose of removing any soluble organic contaminants. Also, no microscopic solid contaminants, such as
particulate coal, were observed on the Sarcobatus wood
sample. It is assumed that Isotopes, Inc. also inspected
their wood sample.
The wood fragments from “gravels containing mammoth bones and artifacts” sent to Isotopes, Inc., dated
4975 ± 180 14 C year B.P. (I-474) (Trautman & Willis,
1966). This date applies to Stratum C1 , the gravel channel
fill. U.P. site sample #35, with a tag marked “U.P. #35sq. I7, black layer,” was a cylindrical segment of wood
(47 mm × 15 mm) identified by Kathryn Puseman of
Paleo Research Institute as Sarcobatus sp. (greasewood),
which is native to the area today. The label “black layer”
may have been a chunk of redeposited Stratum A. The
14
C age of 3838 ± 97 14 C year B.P. (AA-86461) applies
to either Stratum C1 or Stratum C2 . This date and that
by Isotopes, Inc. probably apply to many if not most of
the artifacts from these channel fills indicating they are
essentially Middle Archaic.
Finally, to test for redeposition, we ran a 14 C analysis
on a spirally fractured bone fragment labeled as “U.P. 34,
Lev. 41+11/2 sq. G15” but with no stratum stated. The
age of 289 ± 32 14 C year B.P. (AA-87742), along with
the fact that historic artifacts were recovered from Trench
N (Figure 2), indicates that the sample is probably not
redeposited and the sedimentary matrix is either Stratum
F or Stratum E.
CONCLUSIONS
Based upon the probability that the mammoth skeleton
had sunk into Stratum A, and the fact that a significant
number of artifacts probably came from the B/A contact,
we believe it is likely that Paleoindians interacted with
the skeleton before the deposition of Stratum B and may
have moved some elements upstream that were redeposited later. Paleoindians occupied the B/A contact after the erosion that truncated the paleosol in Stratum A.
Did they kill the mammoth or did they scavenge it? A
close inspection of “butchering marks” reportedly on the
bones of the skeleton, believed to be at Harvard’s Peabody
Museum, may help answer this question. None of the
redeposited mammoth bones have been available for
study and 14 C dating.
How old is Stratum B? It is a pond and spring seep
deposit with tufa and snail shells. Both need to be collected and 14 C dated. The gastropod Succinea sp. is known
from the site, and has been shown to yield accurate 14 C
ages (Pigati, Rech, & Nekola, 2010). A biased guess is that
Stratum B may be a Younger Dryas age (i.e., ∼11,000 to
∼10,000 14 C year B.P.) deposit resulting from a rise in
110
HAYNES ET AL.
the water table due to colder temperatures and less evapotranspiration (Haynes, 2008b). This would have ended
the “Clovis drought” (Haynes, 1991b) represented by the
pedogenesis and erosion of Stratum A. The B/A occupation could be Clovis or possibly proto-Clovis because the
14
C date for the mammoth is at or beyond the earliest
date that Waters and Stafford (2007) accept for Clovis.
However, the earliest date for Clovis may be older than
they suggest (G. Haynes et al., 2007).
How did so many dispersed mammoth bones get upstream into Stratum C1 ? Did Archaic people remove
bones from the mammoth skeleton penecontemporaneously with the filling of Stratum C1 channel? Did some
mammoth bones come from another skeleton upstream?
Or did the Pleistocene hunters move them upstream from
where they were subsequently redeposited to Stratum C?
Finally, should the name be changed to the Sage
Chicken Spring Mammoth site or the Hansen Mammoth
site? The property has always been owned by the late Mr.
John Hansen of Rawlins and now by his son Niels, but
he is not happy with the name U.P. site. Even though
the name Hanson has been used for a Folsom site in
Wyoming (Frison & Bradley, 1980) the Hansen Mammoth site would be a more appropriate name for the
U.P. site. These are some of the questions that will hopefully be answered by renewed investigations of the site
planned by Prasciunas et al. (2012).
The original excavations were sponsored by the National Geographic Society. We thank the late John Hansen and his son
Niels, owner of the site, for permitting the scientific studies and
William Scoggin for sharing his knowledge of the history of the
site. Mary Prasciunas, Fred Nials, Lance McNees, and Allen Denoyer provided access to the site in 2011 and plan excavations in
the near future. George Frison shared his knowledge of the site,
artifacts, and bones with us. Also, we thank Brent Breithaupt,
former director of the Geology Museum, University of Wyoming,
for allowing the resampling of a tusk of the mammoth for radiocarbon dating. The site archives of Cynthia Irwin-Williams
are curated by the Department of Anthropology, University of
Wyoming, Laramie. This includes a box of eight small bone fragments. Most of the artifacts and many bones are curated by the
Peabody Museum, Harvard University. Radiocarbon date calibrations were calculated by Richard J. Cruz at the Arizona-NSF
AMS laboratory, University of Arizona. Expert word processing was provided by Barbara Fregoso and computer graphics by
Jim Abbott. The manuscript was improved by constructive comments by Vance T. Holliday and Bruce B. Huckell, and by the
technical editing of T. J. Ferguson. We also thank Jared Beeton
and an anonymous reviewer for their comments. The anonymous reviewer suggested the third hypothesis for redeposition
of mammoth bone from a Paleoindian activity area upstream.
REFERENCES
Agogino, G.A., Irwin, C.C., & Irwin, H.T. (1962). The Rawlins,
Wyoming Mammoth Kill. Unpublished manuscript.
C 2013 Wiley Periodicals, Inc.
Geoarchaeology: An International Journal 28 (2013) 99–111 Copyright THE U.P. MAMMOTH SITE, CARBON COUNTY, WYOMING, USA
HAYNES ET AL.
Laramie: Anthropology Department, University of
Wyoming.
Bronk Ramsey, C. (2009). Bayesian analysis of radiocarbon
dates. Radiocarbon, 51, 337–360.
Bronk Ramsey, C., Higham, T., Bowles, A., & Hedges, R.
(2004). Improvements to the pretreatment of bone at
Oxford. Radiocarbon, 46(1), 155–163.
Cannon, M.D., & Meltzer, D.J. (2004). Early Paleoindian
foraging: Examining the faunal evidence for megafaunal
specialization and regional variability in prey choice.
Quaternary Science Reviews, 23, 1955–1987.
Frison, G.C. (1978). Prehistoric hunters of the High Plains.
New York: Academic Press.
Frison, G.C., & Bradley, B.A. (1980). Folsom tools and
technology at the Hanson Site, Wyoming. Albuquerque:
University of New Mexico Press.
Grayson, D.K., & Meltzer, D.J. (2002) Clovis hunting and
large mammal extinction: A critical review of the evidence.
Journal of World Prehistory, 16, 313–359.
Haynes, C.V., Jr. (1991a). More on Meadowcroft radiocarbon
chronology. The Review of Archaeology, 12(1), 8–14.
Haynes, C.V., Jr. (1991b). Geoarchaeological and
paleohydrological evidence for a Clovis age drought in
North America and its bearing on extinction. Quaternary
Research, 35, 438–450.
Haynes, C.V., Jr. (2008a). Quaternary cauldron springs as
paleoecological archives. In L.E. Stevens & V.J. Meretsky
(Eds.), Aridland springs in North America. Ecology and
conservation (pp. 76–97). Tucson: University of Arizona
Press.
Haynes, C.V., Jr. (2008b). Younger Dryas “blackmats” and the
Rancholabrean termination in North America. Proceedings
of the National Academy of Sciences of the United States of
America, 105(18), 6520–6525.
Haynes, G. (1991). Mammoths, mastodonts, and elephants.
Cambridge: Cambridge University Press.
Haynes, G., Anderson, D.G., Ferring, C.R., Fiedel, S.J.,
Grayson, D.K., Haynes, C.V., Jr., Holliday, V.T., Huckell,
Geoarchaeology: An International Journal 28 (2013) 99–111
B.B., Kornfeld, M., Meltzer, D.J., Morrow, J., Surovell, T.,
Waguespack, N.M., Wigand, P., & Yohe, R.M., II. (2007).
Comment on “Redefining the age of Clovis: Implications
for the peopling of the Americas” Science, 317, 320b.
Irwin, C., & Irwin, H. (1961). U.P. site field notes,
Anthropology Department, University of Wyoming,
Laramie, Wyoming.
Irwin, C., Irwin, H., & Agogino, G. (1962) Wyoming muck
tells of battle: Ice Age man vs. mammoth. National
Geographic 121(6), 828–837.
Irwin, H.T. (1970). Archaeological investigations at the Union
Pacific mammoth kill site, Wyoming, 1961. National
Geographic Society Research Reports 1961–1962, pp.
123–125.
May, I. (1955). Isolation of organic carbon from bone for 14 C
dating. Science, 121, 508–509.
Pigati, J.S., Rech, J.A., & Nekola, J.C. (2010). Radiocarbon
dating small terrestrial gastropod shells in North America.
Quaternary Geochronology, 5, 519–512.
Prasciunas, M.M., Nials, F., Haynes, C.V., Jr., McNees, L.,
Scoggin, W., & Denoyer, A. (2012). The U.P. Mammoth
Site, Wyoming: What’s up? 77th Annual Meeting of the
Society for American Archaeology, Memphis, TN.
Reimer, P., Baillie, M., Bard, E., Bayliss, A., Beck, J.,
Blackwell, P., Ramsey, C., Buck, C., Burr, G., Edwards,
R., Friedrich, M., Grootes, P., Guilderson, T.,
Hajdas, I., Heaton, T., Hogg, A., Hughen, K., Kaiser, K.,
Kromer, B., McCormac, F., Manning, S., Reimer, R.,
Richards, D., Southon, J., Talamo, S., Turney, C.,
Van Der Plicht, J., & Weyhenmeyer C. (2009). IntCal09
and Marine09 radiocarbon age calibration curves, 0–
50,000 years cal BP. Radiocarbon, 51, 1111–1150.
Trautman, M.A., & Willis, E.H. (1966) Isotopes Inc.
radiocarbon measurements V. Radiocarbon, 8,
161–203.
Waters, M.R., & Stafford, T.W., Jr. (2007). Redefining the age
of Clovis: Implications for the peopling of the Americas.
Science, 315, 1122–1126.
C 2013 Wiley Periodicals, Inc.
Copyright 111