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Archaeobotanical Remains
by Katharine D. Rainey and Sandra Jezik
Introduction
1
To understand prehistoric plant use at Woods Canyon Pueblo, Crow
Canyon researchers collected and analyzed two types of samples: macrofossil
and flotation. Macrofossil samples are pieces of plant material large
enough to be seen with the unaided eye, and excavators retrieve them by
hand as they dig and screen sediment in the field. Macrofossil specimens
constitute a subjective sample of the contents of a given deposit, because
collection depends on what an individual excavator decides to gather (not
every piece of plant material seen in the course of excavation is collected).
The macrofossil samples considered in this study consist predominantly
of wood charcoal.
2
Flotation samples are samples of sediment taken from specific archaeological
contexts. Because they are collected and processed systematically, they
provide the most important and reliable data about prehistoric plant use
at a site. Most flotation samples consist of a standard volume of sediment
collected from contexts where archaeobotanical remains are expected to
be plentiful—for example, primary refuse, secondary refuse, and roof-fall
deposits. The samples are poured into a bucket of water, which is agitated
to separate the organic botanical material from the sediment. The plant
remains that float to the top (hence the term "flotation") are then examined
under a microscope to identify the different plants present. Flotation
is useful in recovering small seeds and other remains that ordinarily
would not be captured in a standard screen used during excavation. Although
flotation samples provide an unbiased sample and therefore better—and
more comparable—data, it is the combined macrofossil and flotation
data sets that provide the best understanding of how the inhabitants of
a prehistoric site used plant resources.
Methods
Macrofossil Samples
3
The first step in analyzing the macrofossil samples from Woods
Canyon Pueblo was to create a subsample by randomly choosing 20 pieces
of wood charcoal from each sample. If fewer than 20 pieces were present,
all were examined. If more than 20 pieces were present, once the first
set of 20 had been analyzed, any additional pieces that were morphologically
distinctive to the naked eye were examined. The pieces were snapped in
order to expose a fresh transverse (cross) section, which was then examined
under a dissecting binocular light microscope at magnifications of 10
to 45X. Specimens were identified only to the level of genus; identifying
items to the species level would have required examining radial and tangential
sections, which we were unable to do because of time constraints and limited
microscope capability. We identified taxa using a modern wood charcoal
comparative collection backed by voucher specimens in the University of
Arizona herbarium.
Flotation Samples
4
Sediment samples for flotation were processed by the Crow Canyon
laboratory staff and were usually a standard size of 1 liter. If more
than 1 liter of sediment was collected in the field, only 1 liter was
processed, and the remainder was set aside for future research. If less
than 1 liter was collected, the entire sample was processed and the volume
was recorded.
5
The samples were poured into a bucket of water, and the water was
stirred to free the organic materials. The mostly nonorganic material
that settled to the bottom of the bucket constituted the "heavy fraction,"
which was collected, allowed to dry, and curated. Carbonized (burned)
remains that floated to the surface were poured into a fine screen, .355-mm
mesh, to be captured as the "light fraction." The light fraction was allowed
to dry for several days and then was poured through a series of geologic
sieves. This process separated the light fraction into 4.75-mm, 2.80-mm,
1.40-mm, .71-mm, and .25-mm portions, which were then individually bagged
and labeled. (Although the size of the original mesh used to capture the
light fraction is .355 mm, smaller particles that adhere to larger particles
while wet can detach as the residue dries and be caught in the .25-mm
screen used during dry screening. Plant remains also continue to break
into smaller pieces whenever a sample is handled.)
6
The light fractions were sorted in two steps. The first step involved
subsampling the wood charcoal. We examined 20 pieces of wood charcoal
from every sample whenever possible. The pieces were randomly selected
from the 4.75-mm portion first, because the larger size allowed for more
confident identification. If it was necessary, we chose individual pieces
from the 2.80-mm portion to round out the 20 pieces. After the subsample
of 20 pieces was analyzed, any morphologically distinctive pieces were
examined.
7
The second step of the procedure was to analyze the rest of the
light fraction (the 0.25-mm sieve size was not sorted, because it was
assumed to contain broken pieces of plant remains from the larger-sized
sieves). The 4.75- and 2.80-mm portions were completely sorted for seeds.
A "species area curve" was used to subsample the 1.40- and .71-mm portions.
This approach maximizes the number of taxa recorded while minimizing the
volume of sample sorted (Adams
1993*1:196). Because the interpretative emphasis of this study was
on the presence or absence of taxa, our goal was to identify the maximum
number of taxa present in a sample, rather than to record the total number
of items identifiable to those taxa. The 1.40- and .71-mm portions were
sorted in increments of 0.90 ml. Each unit of 0.90 ml was measured with
a graduated cylinder. Three successive 0.90-ml units were sorted. If no
new taxa were observed the third time, no more units were sorted for that
sieve size. If new taxa were observed, then another 0.90-ml portion was
sorted; this process continued until no new taxa were found.
8
We analyzed the light fraction using a dissecting binocular light
microscope at magnifications ranging from 10 to 45X. Specimens were identified
using a modern seed comparative collection backed by University of Arizona
herbarium voucher specimens. Reference texts (such as Martin
and Barkley [1961*1]) were also used. If none of these approaches
was successful, the specimen was measured and described as "unknown."
The Sample
9
Of the 160 flotation and 451 macrofossil samples collected during
the three seasons of excavation at Woods Canyon Pueblo, 58 flotation and
73 macrofossil samples were analyzed (36 percent and 16 percent, respectively,
of the total samples within each category). In keeping with Crow Canyon's
sampling strategies at other sites, the samples selected for analysis
were collected primarily from secondary refuse (for example, middens),
primary refuse (for example, ash in thermal features), and mixed deposits
(Table 1).1
In addition, we selected samples collected from naturally redeposited
secondary refuse because in situ secondary refuse (midden) deposits were
not preserved on the steep slopes of the site. Roof-fall deposits and
"unspecified" cultural deposits are also represented. The distribution
of samples by type of deposit is presented in Table
2.
10
A minimum of 34 plant taxa were present in the analyzed flotation
and macrofossil samples (Table
3). Specimens were identified to the most specific taxonomic category
possible. In most cases, this was the genus level. Occasionally specimens
could be identified only to the level of family, and in rare cases, specimens
were identified to species. Because of the potential overlap between the
listed families and genera, more species may be present than are actually
indicated; for example, the category Pinus-type may include both
Pinus edulis and Pinus ponderosa.
11
During analysis, one of three levels of confidence is indicated
for each identification: "absolute," "-type," or "cf." As an example,
an "absolute" identification to the level of species "implies that all
the species of a given genus in the surrounding area have been examined
and the specimen under the microscope could easily disappear in a population
of seeds of the named species" (Bohrer
and Adams 1976*1:1). The label "-type" is used when a well-preserved
specimen has morphological characteristics that are identical to those
of the named species, but not all of the species of that genus that occur
in the local environment have been examined (Bohrer
and Adams 1976*1:1). The label "type" is included only in the tables
of this report and should be assumed to apply in the text. The abbreviation
"cf." is applied to specimens that are difficult to recognize because
of poor preservation or other problems (Bohrer
and Adams 1976*1:1). These three labels are not limited to identifications
made at the level of species; they can be adapted for use with any taxonomic
rank.
12
When a specimen is listed with two genus names, such as "Amelanchier/Peraphyllum"
or "Prunus/Rosa," it means that the specimen could be a member
of either of the two genera, and a more precise determination is not possible.
The order in which the names are given does not indicate which genus is
most likely; the names are simply listed alphabetically. Some wood charcoal
taxa may be listed in the database with both the genus and species listed.
For the purposes of this study, members of the same genus were combined
because it was impractical to examine the necessary radial and tangential
sections. Thus, the genus level was considered to be the most accurate
identification. In this way we strove to record as much information about
a specimen as possible, while reducing the chances for erroneous identifications.
13
Both charred and uncharred archaeobotanical remains were recovered
from Woods Canyon Pueblo (Table
4). Charring is generally considered to probably be the result of
prehistoric cultural activities. Unburned remains are more likely to be
modern or to have been introduced through noncultural processes—for
example, rodent activity and wind—unless a good case to the contrary
can be made on the basis of their archaeological context (Minnis
1981*1:147). Because we can make no such argument for the uncharred
remains from Woods Canyon Pueblo, they are excluded from consideration
in this chapter. Partly charred specimens were included with the charred
specimens for the purposes of this analysis.
14
More-detailed information relating to our analyses and subsequent
interpretations can be found in two on-line publications. For complete
descriptions of the criteria used to identify each plant taxon and part
identified in the Woods Canyon archaeobotanical assemblage, refer to the
Plant
Identification Criteria. For sources of the ethnographic information
presented in this chapter (for example, possible uses of plants), refer
to the Ethnographic
Uses of Plants.
Results
15
The data derived from the analysis of archaeobotanical remains
allow us to at least partly reconstruct plant use at Woods Canyon Pueblo.
In the following sections of this chapter, we examine evidence of plant
use for food, fuel, and construction, and we compare the various sections
of the site in an attempt to discern patterning in the archaeobotanical
assemblages (refer to "Architecture
and Site Layout" for a discussion of the subdivision of the site into
four sections for purposes of comparative analysis). Additional discussions
address a variety of issues related to the physical environment and how
the inhabitants of Woods Canyon Pueblo lived on the land, including the
proximity of agricultural fields to the pueblo, resource depletion, food
stress, and seasonality. Finally, we present a basic reconstruction of
environmental conditions as they may have existed when the village was
occupied.
Food Plants
16
The archaeobotanical remains from Woods Canyon Pueblo demonstrate
that the inhabitants were corn agriculturalists (Table
5). The parts of the corn (Zea mays) plant found most commonly
were cupules and kernels, although cobs, embryos, and stalks were also
recovered. The ubiquity of corn parts (found in 36 of 131 total analyzed
samples) in the Woods Canyon Pueblo archaeobotanical record suggests that
this plant was a major source of food. The cupules and cob fragments are
probably the remains of cobs that were burned for fuel after the corn
was shelled.
17
Although it is likely that the people of Woods Canyon Pueblo also
ate squash (Cucurbita) and beans (Phaseolus), as did
inhabitants of other ancient Pueblo sites in the region, no remains of
these plants were identified in the flotation or macrofossil samples that
were analyzed. It is possible that squash and beans were not part of the
inhabitants' diet, but it is more likely that the remains are missing
because of poor preservation and/or the methods used to prepare these
plants for consumption—they are very fragile and might have been
prepared in ways (for example, boiling) that would not have led to accidental
charring and discard. It is also possible that bean and squash remains
are present in the many samples that we did not examine; more samples
were not analyzed than were analyzed.
18
A variety of wild resources were available to the people of Woods
Canyon Pueblo for food (Table
5). Remains of virtually all these potential food plants were identified
in the flotation samples. Cheno-am (Chenopodium/Amaranthus)
seeds were the most common, occurring in 16 samples. Goosefoot (Chenopodium)
and pigweed (Amaranthus) grow in disturbed habitats such as are
found in fields and along paths; therefore, they were probably abundant
in the vicinity of the site. The inhabitants of Woods Canyon Pueblo might
have collected only the seeds, or the seeds might have been transported
incidentally with whole plants, which can be eaten as greens. Since the
vegetative parts of cheno-ams and purslane (Portulaca) are usually
quite bitter by the time their seeds are mature, the presence of seeds
in the Woods Canyon assemblage probably indicates that it was the seeds,
not the greens, that were intentionally collected as food.
19
Groundcherry (Physalis) seeds were also quite common in
the archaeobotanical record at Woods Canyon Pueblo, being found in 12
flotation samples. Groundcherry is another weedy species that grows in
disturbed environments. People probably brought the fruits, which mature
in late summer and early fall, into the pueblo, and the seeds somehow
were charred and became part of the archaeobotanical record.
20
The presence of burned pine cone fragments in four samples is indirect
evidence of the consumption of pinyon pine (Pinus edulis)
nuts by the inhabitants of the pueblo. Pinyon pine grows on the site today.
Since the nut-crop yield varies from year to year, this resource probably
would not have been dependable, but in good years, it would have provided
abundant food. Purslane (Portulaca) seeds could have been found
in many of the same places as the cheno-am and groundcherry plants, as
it, too, thrives in disturbed habitats. Other seeds occurred in lower
numbers but could have been eaten by the people of Woods Canyon Pueblo
nevertheless.
Remains in Primary Refuse
21
The best information on the use of plants for food at Woods Canyon
Pueblo comes from two sources: primary refuse from hearths and secondary
refuse from middens. Primary refuse, which was found at the place where
it was generated, gives us a picture of the last few cooking episodes
in a hearth and thus provides direct evidence of what the inhabitants
ate. Flotation samples from four hearths in three kivas (Structures 2-S,
6-S, and 8-S) yielded evidence suggestive of food preparation at the site
(Table 6). Unfortunately,
one hearth (Feature 8) in Structure 2-S and the hearth in Structure 6-S
contained no reproductive plant parts. The charred cheno-am seeds found
in the hearth in Structure 8-S (Feature 1) may be the remains of a batch
of seeds that were accidentally burned in the process of being parched.
Groundcherry seeds also were among the food remains found in this hearth.
In ethnographic studies, groundcherry fruit is usually described as being
boiled, which generally does not lead to accidental burning, but the contents
of the cook pot could have bubbled over into the fire, allowing some seeds
to become charred. It is also possible that the Woods Canyon inhabitants
roasted the fruits.
22
A seed belonging to the Solanaceae family was found in one of the
hearths in Structure 2-S (Feature 3). Given the prevalence of this genus
in other flotation samples from the site, it is probably another groundcherry
seed; however, other members of this family also grow on the surrounding
landscape today. Corn in various forms was found in both hearths that
yielded reproductive plant parts. The kernels could have been roasted
or parched over the fire, but the cupules are probably remnants of cobs
used for tinder and fuel.
Remains in Secondary Refuse
23
Flotation samples from secondary refuse in middens complement the
samples of primary refuse from hearths. Secondary refuse is trash, including
ash from hearths, that accumulates over a period of time; it provides
indirect evidence of what foods were consumed, by revealing the things
that were discarded. Middens in each area of the site were tested, and
40 flotation samples were collected from in situ secondary refuse. Many
more taxa were present in these samples (Table
7) than were present in the primary refuse samples (Table
6).
24
Remnants of pine cones were found in four samples. Historically,
green pinyon cones have been heated over fire or among coals to release
the nuts, a process that can result in charring. Alternatively, the cones
could have been used for tinder or fuel.
25
Charred goosefoot (Chenopodium) and purslane (Portulaca)
seeds were also found. These seeds could have entered the archaeobotanical
record in a variety of ways. They could have been charred in the process
of being parched, or they could have been unintentionally fried with the
greens and discarded into the fire. As stated earlier, however, their
presence is most likely the result of a charring accident during parching.
26
Ricegrass (Stipa hymenoides) caryopses were found in two
flotation samples. The grain of this late spring-early summer plant has
a very tough outer coat, which must be removed to expose the edible interior.
In the ethnographic literature (refer to the Ethnographic Uses of Plants), the most commonly recorded technique for accomplishing
this is to light the grass over a fire, then catch the inner grains as
they fall out. Hedgehog cactus (Echinocereus) seeds were found
in two flotation samples. Because a common method of removing spines from
cactus fruit is to burn them off, these seeds probably represent a roasting
accident. There were other charred seeds that might have been leftovers
from food processing and consumption, and they are listed in Table
7.
27
Corn (Zea mays), groundcherry (Physalis), and
cheno-ams were the most common taxa identified in secondary refuse deposits,
mirroring their prevalence in the primary refuse samples. These three
foods are thus most likely to have been dietary staples for the residents
of Woods Canyon Pueblo, although additional food resources also appear
to have been used on occasion.
Fuel Sources
28
At least 20 wood taxa were present as charcoal in the flotation
and macrofossil samples (Table
8). Overall, juniper (Juniperus) and pine (Pinus)
were the most common woods, followed by sagebrush (Artemisia)
and mountain mahogany (Cercocarpus). Juniper and pine are the
dominant woods on the landscape today, suggesting that a pinyon-juniper
forest was also present during the occupation of Woods Canyon Pueblo.
Sagebrush is very common in fallow fields. Mountain mahogany is usually
associated with pinyon-juniper woodlands and is common today in the area
of the site. Cottonwood/willow (Populus/Salix) charcoal is less
common in the assemblage than these taxa, but still present. Cottonwood
and willow grow in riparian environments and are found in the bottom of
Woods Canyon. Excavators found other charred wood taxa that are also common
on the modern landscape in upland and lowland habitats (Table
8).
29
One way to study fuel use is to examine wood charcoal found in
kiva hearths. Plant remains from four hearths in three kivas (Structures
2-S, 6-S, 8-S) were analyzed for this study (Table
9). These samples were collected from primary refuse and thus represent
the final use of the hearths. Juniper and pine were the most common taxa,
appearing in samples from all four hearths. The large limbs of these trees
and their prevalence in the area would have made them the best choices
for fuel.
30
Sagebrush was the next-most-common taxon identified in the hearth
samples (present in three of four hearths). Ethnographically, sagebrush
has been considered a second-choice fuel. It is, however, one of the first
shrubs to grow back in old-field succession, which means that it would
have become more prevalent as more and more of the pinyon-juniper forest
was cleared for agricultural fields. Charcoal from serviceberry/peraphyllum
(Amelanchier/Peraphyllum), mountain mahogany, and ephedra (Ephedra)
were found in two hearths; these and the other woods all appear on the
landscape today, but they might have been less common when Woods Canyon
Pueblo was inhabited. Alternatively, these shrubs might have been used
less often for fuelwood because of their other desirable qualities—serviceberry,
for example, yields an edible fruit, which might have made this plant
a more important food resource than fuel source.
31
Another way to study fuel use is to examine wood charcoal cleaned
from hearths and discarded in the middens. The charcoal from the secondary
refuse in the middens (Table
10) presented much the same picture as did the charcoal from primary
refuse in hearths. Juniper and pine are the dominant taxa, followed distantly
by sagebrush and mountain mahogany. These four taxa appeared in middens
across all four sections of the site.
32
Three additional taxa were found in the midden samples—saltbush
(Atriplex), bitterbrush (Purshia), and rose (Rosa).
These taxa were relatively rare. They probably were found only in the
middens because more midden samples were analyzed and because middens
were subject to longer periods of deposition than were hearths. The remains
of these shrubs were still very rare in the secondary refuse deposits,
occurring in only one or two samples, which suggests that they were used
infrequently as fuelwood.
33
One interesting flotation sample from Nonstructure 7.6-N contained
saltbush, rabbitbrush (Chrysothamnus), and lemonade berry (Rhus)
charcoal—three of the four traditional Hopi kiva fuels (only greasewood
[Sarcobatus] was missing from the mix). This flotation sample
was collected from secondary refuse, so the origin of the charcoal is
uncertain, although it likely represents discarded fuelwood.
Construction Materials
34
Wood charcoal from Woods Canyon Pueblo can also help us identify
construction materials used at the site. The small sample from construction
contexts (N = 8) limits the conclusions that can be made, however. One
flotation sample and seven macrofossil samples were analyzed from roof-fall
and wall-fall deposits in Structures 1-S, 2-S, 3-S, 5-S, 6-S, and 7-S
(Table 11). The samples
from Structures 1-S, 2-S, and 6-S did not contain any cultural materials.
Juniper charcoal and a corn cob were found in the wall-fall and roof-fall
debris of Structure 7-S. The roof of Structure 7-S is believed to have
burned, so the charcoal might be a piece of a juniper roof beam. The corn
could have been sitting on the roof or hanging from the rafters when the
roof burned and collapsed, or it could have been incorporated into the
roofing materials during construction.
35
The two macrofossil samples collected from roof-fall deposits in
Structure 5-S contained juniper, pine, and sagebrush charcoal. The juniper
and pine might be remnants of burned roof beams. The sagebrush could have
been used as secondary roofing material. The flotation sample from Structure
3-S was collected from a layer of ash in the roof fall of Structure 3-S;
it yielded juniper wood, pine bark scales, and a cheno-am seed. If the
ash is the remains of burned roofing materials, then the juniper wood
might be from a roof timber, and the pine bark scales from earlier pine
beams. Alternatively, the ash could have been dumped as secondary refuse
after the roof collapsed, or it could have rested on top of the roof and
collapsed with it. If the deposit was secondary refuse, then the plant
remains recovered could be from a hearth that was cleaned out. Cheno-ams
are a weedy species, so the seed found in the sample might have blown
or fallen onto the roof and become incorporated into the roof-fall deposits
when the roof burned.
36
In summary, although our conclusions are limited by the small sample
size, it seems that the wood of choice for roof timbers was juniper. Juniper
is the predominant wood in the tree-ring samples from the village, along
with some pinyon pine. Sagebrush appears to have been used as roofing
material as well.
Intrasite Comparisons
37
In this section, we compare the plant remains found in the four
spatially discrete sections of Woods Canyon Pueblo: the upper west side,
the canyon bottom, the east talus slope, and the rim complex (see "Architecture
and Site Layout" and Database
Map 330). Comparisons of plant use among these four areas were
central to the questions posed in "Research
Objectives and Methods." In this chapter, we present the results of
spatial and temporal analyses of the archaeobotanical assemblage in an
attempt to (1) shed light on functional differences, if any, between the
four sections of the site and (2) discern changes in plant use through
time. Together, these analyses provide a picture of plant use at Woods
Canyon Pueblo.
38
Plant remains from several different types of deposits were included
in these studies (Table
2). The main data are derived from analysis of samples from primary
and secondary refuse. A third important source of information is naturally
redeposited secondary refuse—that is, trash that has been moved from
its original location by nonhuman forces such as wind, water, or gravity.
Although this material has been redeposited, it almost certainly is in
the same section of the site where it was originally discarded.
39
Other types of deposits represented in the archaeobotanical assemblage
from Woods Canyon Pueblo include mixed refuse (an assemblage containing
a combination of the main refuse types) and cultural deposits that are
"not further specified" (deposits known to be the result of prehistoric
human activity, but for which we cannot determine the exact type). In
our analysis, we look at these types of deposits collectively as well
as separately. Grouping the samples from different types of deposits allows
us to increase the sample size; considering them separately provides insights
into the different types of activities that might be represented. We begin
by looking at how sample size and preservation affect analytic results
and interpretations.
Methodological Concerns
Sample Size and Diversity
40
Sample size can affect analytic results in two ways: a large sample
is expected to have a greater diversity of remains, while a smaller sample
may not include a representative sample of all the plants that were used
at a site. There are two types of sample size that concern us here: flotation
sample size and the size of the overall site sample. "Flotation sample
size" refers to the amount of sediment processed for each sample. "Overall-site
sample size" refers to the number of flotation samples taken from each
section of the site, as well as the total number collected from the entire
site. Because the Woods Canyon Pueblo flotation samples were a uniform
1.0 liter in volume, we can eliminate flotation sample size as a potential
source of bias in this study.
41
We cannot, however, discount the possible effect that the overall-site
sample size (that is, the number of samples from each section and from
the entire site) might have had on our results. Because there were a limited
number of appropriate primary and secondary refuse contexts in each section
of the site, we selected an unequal number of flotation samples from each
for analysis (see Table
12). Twice as many samples from the canyon bottom were analyzed (N
= 27) as were analyzed from the upper west side (N = 12) and east talus
slope (N = 13), and four times as many samples were analyzed for the canyon
bottom as for the rim complex (N = 6). The small number of analyzed samples
from the rim can be attributed to the small number of proveniences that
were test-excavated in that section of the site. Clearly, the variation
in number of analyzed samples from the different site sections creates
the potential for overall-site sample size bias.
42
In an attempt to compensate for potential bias, we applied the
statistical program DIVERS (Kintigh
1998*1) in our examination of (1) the distribution of plant remains
among the four sections of the site, (2) the distribution of plant remains
among the various types of deposits, and (3) the distribution of plant
remains in the in situ secondary refuse assemblages. The DIVERS program
is well suited to such analyses, because it compares the actual assemblage
with simulated assemblages that are created with respect to probability
distribution of the actual assemblage. Since sample size may have affected
the quantity and types of archaeobotanical remains observed, we wanted
some way to make spatial and temporal comparisons that would not be biased
by the effects of sample size. The DIVERS program allowed us to determine
whether the diversity of assemblages was greater than what we would have
expected given their sample size (Kintigh
1984*1:44).
43
There are two assumptions behind the DIVERS approach to simulating assemblages
(Kintigh 1984*1:45). The
first is that "for a given artifact typology and cultural situation there
is an underlying frequency distribution" of items in the classification
system, determined through culture and societal norms (Kintigh
1984*1:45). The second assumption is that the assemblage was created
by choosing randomly from the potential pool of elements. That is, a component's
ultimate presence in the assemblage is influenced by the probabilities
based in the societal norms (Kintigh
1984*1:45). Through these assumptions, the model provides a randomly
created grounds for comparison. That, in turn, allows us to draw conclusions
about the extant data set (Kintigh
1984*1:45).
44
The Woods Canyon Pueblo data do not violate the first assumption,
but it is possible that they violate the second. This is not a great concern,
however, since we would expect that the archaeobotanical assemblage at
Woods Canyon Pueblo was not created randomly. The purpose of a simulation
is to create a confidence interval through which we can determine whether
the actual assemblage deviates from expected ranges, and if so, by how
much.
45
The DIVERS program employs a Monte Carlo–style method (Kintigh
1998*1:51) that creates a set of simulated assemblages by drawing
items independently and at random, according to the probabilities found
in the combined frequency distribution of the individual assemblages.
From the given assemblage, a sample is chosen randomly with the same sample
size as the actual assemblage; if the actual sample has 25 elements, then
the simulated assemblage will have 25 elements as well. Finally, the approach
creates a large number of randomly simulated assemblages; from these,
it computes an expected range of diversity for the samples (Kintigh
1984*1:47). Therefore, using DIVERS analysis, we can attempt to compensate
for the small sample size from certain sections of Woods Canyon Pueblo.
46
The first step in examining the four sections of the site for diversity
of plant remains was to compare their assemblages with the randomly assorted
simulated assemblages (Table
12, Figure 1).
The results of the simulation show that the numbers and ubiquities of
plant taxa in the upper west side and east talus slope are very similar
to the distributions expected if the plant taxa were randomly apportioned
among the samples—that is, they fall within the 90 percent confidence
interval. The rim complex and the canyon bottom differ from the other
two sections in that they have more plant taxa than we would expect if
the archaeobotanical remains were apportioned randomly. This greater richness
might be the result of sample size, but it could also be related to preservation
or prehistoric human behavior.
47
With 34 different plant taxa and parts, the in situ secondary refuse
assemblages have the greatest number of taxa of all deposit types (Table
13). Because 40 of the 58 Woods Canyon Pueblo flotation samples are
from in situ secondary refuse, these samples have the greatest effect
on the analyzed assemblage as a whole (Table
2, Figure 2).
When we consider only the archaeobotanical remains from in situ secondary
refuse, the pattern of greater richness for the rim complex and canyon
bottom is less striking (Table
14). The richness of the rim-complex assemblage is at the upper limit
of the 90 percent confidence interval, whereas the richness of the canyon-bottom
assemblage is close to the upper limit but still below the boundary (Figure
3).
48
Why do the samples from the canyon bottom and rim complex have
more plant taxa than expected? More flotation samples were analyzed from
the canyon bottom than from the other sections, which would lead us to
expect to find a greater number of plant taxa there. The diversity analysis
theoretically corrects for this bias, however, which leads us to infer
that the canyon bottom has even more taxa present than its large sample
size would predict. Thus, larger sample size alone does not seem to account
for the greater-than-expected richness in the canyon bottom. Instead,
preservation or behavioral factors could be playing a role. The rim complex
also has a greater-than-expected richness of plant taxa and parts. This
is unexpected, because the rim complex has the fewest analyzed flotation
samples (six). To understand the canyon-bottom and rim-complex assemblages,
we must turn to alternative explanations such as differential preservation
and behavioral differences.
Preservation
49
Factors that influence the preservation of archaeobotanical materials
include temperature variation and extremes, sediment conditions such as
pH and moisture content, and the depth of sediment covering the plant
remains. Exposure to the elements probably played a large role in the
preservation of plant remains at Woods Canyon Pueblo. The rim complex,
situated high above the canyon bottom, is susceptible to considerable
wind and water erosion, as well as to temperature extremes. In addition,
it has much thinner midden deposits, which would afford less protection
to the plant materials in those deposits. We would expect preservation
to be poorer there. The canyon bottom, on the other hand, has deeper middens,
which would afford buried plant remains better protection from the elements.
The middens in the canyon bottom are visibly ashier, lending support to
the idea that organic materials in this part of the site were better preserved.
The archaeobotanical assemblages from both the rim complex and the canyon
bottom, however, are characterized by greater-than-expected richness.
Thus, although differential preservation may have had some effect on the
Woods Canyon archaeobotanical assemblages, this factor alone cannot explain
all of the observed patterns.
Spatial Analysis
50
Spatial analyses of the archaeobotanical remains from Woods Canyon
Pueblo were conducted in an effort to determine whether the four sections
of the site—the upper west side, the canyon bottom, the east talus
slope, and the rim complex—had different functions. First, to maximize
sample size, we evaluated the data from all analyzed flotation samples
from all contexts. Then, in an attempt to identify specific activities
that might have taken place in the different sections, we focused on flotation
samples from in situ secondary refuse and on macrofossil and flotation
samples from primary refuse in kiva hearths. Within each group, we looked
at reproductive plant parts for insights into food use and at wood charcoal
for evidence of fuel use. Comparisons were made on the basis of the ubiquity
of each plant taxon and part. Data patterns were tested using the DIVERS
program, which was run at least twice for each set. If the two trials
produced different results, the program was run a third time; if the results
of the first two trials agreed, no further trials were run. The results
of these tests are presented below.
All Contexts
51
When the flotation data from all contexts at Woods Canyon Pueblo
are considered, the four site sections are basically similar in terms
of taxa and parts present; generally, the same taxa appear in all four
areas (Table 12).
Yet, as the diversity analysis demonstrated, the rim complex and canyon
bottom have a greater number of taxa than would be expected when compared
with the simulated assemblages (Figure
1). Apparently, some factor is exerting an influence on the samples
from the rim and canyon bottom that is not a factor in the samples from
the other two sections of the site.
52
When only reproductive taxa are considered, the four sections of
the site seem generally similar in terms of food use—corn (Zea
mays), cheno-ams, and groundcherry (Physalis) were the most
commonly recovered food plants in the analyzed samples (Table
15). However, the canyon bottom has the greatest diversity, with 17
seeds and other parts indicative of food use, and the east talus slope
has the fewest food taxa, with six. Rarer seeds, such as juniper (Juniperus),
chokecherry/rose (Prunus/Rosa), and ricegrass (Stipa hymenoides),
occurred only in the canyon bottom.
53
These differences may be due to preservation or human behavior,
but we cannot rule out the effects of sample size. The diversity analysis
of reproductive taxa shows that the assortment of taxa is within the expected
range (Table 15, Figure
4). The notable variety of foods in the canyon bottom could be the
result of longer occupation in this part of the site—because this
section was occupied first, we would expect to see a greater variety of
foods accumulate over time in the archaeobotanical record. Also, the deeper
middens would have promoted preservation of plant refuse. Thus, although
the assemblage of reproductive plant parts from the canyon bottom is not
unexpectedly diverse for its sample size, it could still reflect better
preservation and longer occupation. The range of food remains recovered
could also indicate that the canyon bottom was an area of the site where
foods were routinely prepared.
54
The small number of food-plant taxa found in the rim complex warrants
discussion. The two most common food plants at the site—corn and
cheno-ams—are present in the samples from the rim complex, yet few
other seeds were found there. If the rim complex was a public space used
for ceremonial activities or feasting, we might not expect to find much
evidence of food preparation. Rather, food might have been prepared at
residences and brought to the public space, with the refuse being discarded
at the residence locations. The middens in the rim complex are very shallow,
which suggests that refuse was not routinely discarded there. Because
the rim complex is so exposed and the middens are so shallow, we would
also expect poor preservation compared with the preservation of plant
remains in other parts of the village. Yet the number of food taxa present,
although small, is not unusually small for the size of the sample.
55
The archaeobotanical remains from the upper west side and east
talus slope do not show any patterns out of the ordinary with regard to
food use. Although these sections of the site have fewer food taxa than
were found in the canyon-bottom samples, many of the same plants are represented.
The presence of food taxa is consistent with the interpretation of the
upper west side and east talus slope as areas of the village where food
was prepared.
56
Just as food use was similar in the four sections of the site,
so, too, was fuelwood use. When the taxa identified in the wood charcoal
assemblage from the 58 flotation samples were tabulated, the four areas
had almost identical plant lists (Table
16). The most common fuel types in all areas are juniper (Juniperus),
pine (Pinus), and sagebrush (Artemisia). One reason
for the apparent similarity in fuel use among the four sections is that
the environment offered all people the same choices of wood for food preparation,
heat, and light.
57
When fuelwood diversity is examined by site section, both the rim
complex and the canyon bottom have a greater-than-expected richness of
fuel remains (Figure
5), which in turn contributes to the higher overall richness of these
two sections discussed above. The deeper midden deposits in the canyon
bottom might have promoted the preservation of less-common woody taxa.
The increased diversity could also be partly the result of more people
inhabiting this part of the pueblo for a longer period of time. In the
case of the rim complex, preservation is not believed to have contributed
to the richness of fuelwood taxa, because preservation there was very
poor. Instead, it is possible that human behavior—possibly associated
with public functions—contributed to the observed diversity.
In Situ Secondary Refuse
58
Forty flotation samples from in situ secondary refuse were included
in this analysis (Table
14). Because secondary refuse is discarded trash, the analysis of
reproductive plant parts and wood charcoal remains in samples collected
from these contexts provides indirect evidence of food and fuel use, respectively.
Patterns discerned in the assemblage of reproductive plant parts in the
samples from in situ secondary refuse are similar to those seen when all
contexts are considered together. Unlike the occurrence of reproductive
plant parts in all contexts, however, the occurrences of assorted reproductive
parts in the in situ secondary refuse are all within the ranges predicted
by the diversity analysis. A similar situation obtains for the wood charcoal
assemblage, that is, the assemblage from the in situ secondary refuse
presents patterns that are similar to those documented for all contexts
combined. And, unlike the distribution of woody taxa when all contexts
are considered together, the distribution of woody taxa in secondary refuse
was within the expected range.
Primary Refuse in Kiva Hearths
59
To complete our intrasite comparison, we examined eight samples
from primary refuse contexts, which provide direct evidence of food and
fuelwood use. Seven of these samples were flotation samples from hearths;
one was a macrofossil sample from a nonstructure surface. The samples
were taken from the rim complex, canyon bottom, and upper west side; no
good primary refuse contexts were excavated on the east talus slope (Table
17). Overall, the three areas were similar in terms of the taxa identified
in primary refuse, and they all had the expected number of taxa for their
sample sizes. There is, however, one interesting departure from the sample
profile: the samples from primary refuse in the rim complex contained
wood charcoal only. The absence of reproductive plant parts in the kiva
hearth in the rim complex suggests that no foods were prepared in the
last fires burned in this structure. This inference is consistent with
the earlier interpretation that the rim complex might have been an area
to which people brought foods prepared elsewhere in the village.
Temporal Analysis
60
We turn now to an examination of temporal patterning in the Woods
Canyon Pueblo archaeobotanical assemblage. Specifically, we want to understand
whether the inhabitants used plants in different ways over time. Temporal
comparisons among the four sections of the site are difficult to make,
because chronological data are limited; nonetheless, an attempt was made
to identify early and late components on the basis of tree-ring, pottery,
architectural, stratigraphic, abandonment, and structure-location data
(see "Chronology").
61
It is thought that the canyon bottom was the first inhabited section
of the site, with occupation there beginning in the mid–A.D. 1100s.
This area is also believed to have been occupied longer than the other
areas, although it may not have been in use during the final years of
occupation. Occupation in the upper areas of the site—that is, the
rim complex, the upper west side, and the east talus slope—started
later, sometime in the 1200s, but there appears to have been some overlap
between the occupation of these areas and that of the canyon bottom.
62
For the purposes of this study, we used two temporal groupings—early
and late—but we defined them differently for different analyses.
For the first set of temporal comparisons, we examined early and late
sections of the site: the canyon bottom is "early," and the upper
west side, rim complex, and east talus slope are "late" (refer to "Chronology"
for a discussion of the assignment of site sections to early and late
periods). Fifty-eight flotation samples were included in these comparisons
(Table 18). In the
second set of temporal groupings, we used a much smaller subset of specific
dated contexts—all of them nonstructures—that had been
assigned to the early and late phases of occupation on the basis of pottery
types and stratigraphy. In addition, Structure 7-S was assigned to the
late group because a tree-ring sample collected from it yielded a cutting
date of A.D. 1257. In all, six flotation samples and 18 macrofossil samples
from specific dated contexts were used in the second set of comparisons
(Table 18). We chose
to group the flotation and macrofossil samples together for this analysis
in order to create a larger set of specifically dated contexts.
Our interpretations are based on the ubiquity of the plant taxa
for each time period.
Food and Fuel Use Over Time
63
A comparison of all charred plant parts between the early and late
sections of the site reveals general similarities in assemblage composition
and plant ubiquity (Table
19). The same pattern is seen in a comparison of the smaller set of
specific contexts dated on the basis of pottery types and stratigraphy,
plus one tree-ring cutting date (Tables
20 and 21). These
results suggest that people gathered many of the same foods and fuels
through time.
64
When all taxa for the early and late sections of the site are examined
using the DIVERS program, however, the early section of the site appears
to have a greater richness of taxa than would be expected for the number
of samples examined (Figure
6). The early occupants of Woods Canyon Pueblo may have had access
to a greater variety of plants, or they may have preferred a more diverse
set of resources to satisfy their needs, than did later occupants. Because
the canyon bottom, which was occupied early in the site's history, has
deposits that are very well preserved, we cannot completely rule out preservation
as a contributing factor. No DIVERS analysis was attempted on the smaller
dataset composed of specific contexts, because the sample size was too
small.
65
Not included in the foregoing discussion are insights pertaining
to changes in specific taxa over time, although Popper
(1988*1:61) warns that it can be risky to compare ubiquities of taxa.
Among six food resources present through time, the only major change is
that cheno-am seeds decrease notably in ubiquity in the later sections
of the site (Table 19),
suggesting less access to, or harvesting of, this wild food resource.
An increase in the recovery of sagebrush (Artemisia) charcoal
in the late sections of the site may indicate that more agricultural land
was returning to fallow during this time. A drop in the ubiquity of pine
(Pinus) charcoal relative to juniper (Juniperus) through
time (Table 19) may
partly relate to the ability of juniper to regenerate more quickly than
pine, which would have led to a greater proportion of juniper on the landscape
late in the Pueblo occupation of the area (Kohler
1992*2:263).
Proximity of Agricultural Fields
66
The archaeobotanical record for Woods Canyon Pueblo was examined
for evidence that might allow us to determine the proximity of agricultural
fields to the site. If the fields were close by, it would have been easier
to transport whole ears of corn to the pueblo for processing, which would
have resulted in the deposition of cobs, stalks, and cupules at the site.
If the fields were distant, it is more likely that corn would have been
shelled in the field to save transportation costs, since the volume of
shelled kernels is half the volume of the original complete ears (Thornton
1984*1:267 [1845]). In that case, we would expect to find only corn
kernels at the site. Corn cobs, stalks, and cupules were found in both
flotation and macrofossil samples from Woods Canyon Pueblo, indicating
that the agricultural fields were probably located close to the village.
67
It is possible that Nonstructure 1-N, in the canyon bottom, was
an agricultural garden, although the evidence is ambiguous. Pieces of
corn plants, such as cupules, kernels, and stalk segments, do occur in
the flotation and macrofossil samples from the canyon bottom, but they
also occur in samples from the other areas of the site (Table
22).
Resource Depletion and Food Stress
68
Resource depletion and food stress are related, though not identical,
concepts. Resource depletion can lead to food stress, and vice versa.
Resource depletion occurs when people use up plants that were formerly
abundant, so that the plants become less common. Food stress occurs when
there is not enough to eat, or when there are not enough nutritious foods
to eat. It is thought that resource depletion and food stress might have
occurred in the Mesa Verde region before the major emigrations from the
area (Kohler and Matthews
1988*1:559; Stiger 1979*1:142).
69
If resource depletion occurred at Woods Canyon Pueblo, we would
expect previously used taxa either to stop appearing or to be found in
fewer contexts in the later period. Both juniper and pine, however, are
still present in the late assemblages (Table
19). These woods seem to have provided most of the fuel and construction
wood throughout the occupation of the village. Structures 10-S and 11-S,
at the base of the cliff east of the main drainage, date to the post–A.D.
1280s and have juniper roof beams. Structure 7-S has a construction date
of A.D. 1257, which places it later in the occupation of the pueblo. In
this kiva, pieces of juniper and pine wood were found on Surface 2, suggesting
that suitable juniper and pine timbers were still available during the
later period of occupation.
70
There is a slight increase in the prevalence of sagebrush in later
contexts; however, even then it does not seem to have been a major fuel
source. The ethnographic literature suggests that sagebrush is a second-choice
fuel because of its unpleasant odor when burned. It is common in fallow
fields and would have become more available as land was cleared for agriculture.
Although cottonwood and willow occur in samples from early contexts, there
is less of these types in the later samples, which may mean that the people
of the village had cleared out the riparian areas for fields. In summary,
some resource depletion may have occurred at Woods Canyon Pueblo, but
it does not seem to have placed severe limits on the inhabitants' choice
of fuel.
71
There are a variety of coping mechanisms for dealing with food
stress. People can eat more of the foods that they normally use to supplement
poor harvests, or they can shift to foods they would normally ignore.
They also can alter their methods of food preparation so that foods yield
either more energy or more bulk (Adams
and Bowyer 2002*1). Adams
and Bowyer (2002*1) focus on the relative presence of higher-cost
or less-desirable foods. "Higher-cost" foods are those that require considerable
processing to be edible, or can be acquired only from great distances.
Two examples of higher-cost foods are cactus fruits, with their numerous
spines, and lemonade berry, with its sour fruit and large seeds.
72
"Less-desirable" foods are more difficult to categorize because
they are deemed less desirable largely on the basis of personal preference.
Higher-cost foods can also be less-desirable foods, because people may
decide that eating the plant is not worth the costs involved. Less-desirable
foods also might have a bad odor, be less nutritious, or have an unpleasant
taste. An example of such a food is wolfberry (Lycium), the fruit
of which, unless picked at just the right stage of ripeness, is very bitter.
73
If food stress occurred at Woods Canyon Pueblo, we would expect
to find more higher-cost or less-desirable foods, as compared with weedy
species, such as cheno-ams, groundcherry, and purslane. Weedy plants produce
abundant seeds that are easy to gather; moreover, they grow in disturbed
areas (such as agricultural fields) and might even be encouraged to grow
in such locations. If environmental conditions were to fluctuate and the
weather were to change, the agricultural crops and the associated encouraged
weeds might fail, leaving only the hardier higher-cost or less-desirable
resources to eat.
74
At Woods Canyon Pueblo, the most desirable weedy plants like cheno-ams,
groundcherries, and purslane were still being used in large quantities
in the later contexts, comparable to their use in early contexts. Hardier
or higher-cost resources, such as juniper, hedgehog cactus, serviceberry,
plum/rose seeds, and knotweed (Polygonum) achenes are scattered
through both early and late contexts. These secondary resources seem to
have been used occasionally to supplement the main wild resources (cheno-ams
and groundcherries), but they do not indicate the major dietary shift
we would expect if there had been food stress.
Seasonality
75
The range and diversity of archaeobotanical remains found at Woods
Canyon Pueblo indicate that the site was occupied during at least a good
portion of the calendar year (see Table
5). Ricegrass grains are one of the first foods available in the late
spring; pigweed and goosefoot seeds are available in the summer; and it
appears that the Woods Canyon inhabitants gathered groundcherry fruits
and purslane seeds in the late summer and early fall. If the people of
Woods Canyon Pueblo grew their corn in nearby fields, someone had to have
been there to prepare and plant the gardens in the spring, weed the fields
during the growing season, and then harvest the corn in the fall. From
these lines of evidence, it appears that the site was occupied from at
least spring into fall. Although there is no direct archaeobotanical evidence
to support the inference that the pueblo was occupied during the winter
months, the heavy investment in architectural facilities at the site constitutes
indirect evidence for this interpretation.
76
It is more difficult to determine the season or seasons of emigration
from the site. Since we cannot definitively say which structures were
the last to be occupied at Woods Canyon Pueblo, the archaeobotanical assemblage
is of little help in addressing this question.
The Past Environment
77
The natural environment as it existed during the occupation of
the pueblo seems to have been similar to the modern natural environment.
Many of the plants seen on the landscape today were available to the inhabitants
of Woods Canyon. Both dry and riparian habitats were present, judging
from the spectrum of archaeobotanical remains; however, differential use
and preservation make it difficult to estimate the relative proportions
of mesic to xeric environments in the past. The basic successional stages
were all present in the past, from mature pinyon-and-juniper woodlands
to old-field sagebrush and rabbitbrush shrubs, to the weedy cheno-ams,
purslane, and groundcherry that grew in disturbed areas.
Summary
78
We analyzed 58 flotation samples and 73 macrofossil samples from
Woods Canyon Pueblo for this study; most of the samples were collected
from primary and secondary refuse. The results show that the people of
Woods Canyon grew corn and gathered a variety of wild plants such as cheno-ams
and groundcherries. Their preferred fuels appear to have been juniper,
pine, and sagebrush. Pine and juniper were also used in construction.
79
Similar foods and fuels were used in each of the four sections
of the site. Both the canyon bottom and rim complex, however, revealed
some unexpected patterning. For example, a greater-than-expected number
of plant taxa were documented in the samples from these two sections,
a circumstance that may be attributed primarily to the greater number
of wood-charcoal types present. A combination of better preservation and
longer occupation might explain the pattern observed in the canyon-bottom
assemblage but does not account for the same pattern in the rim complex,
with its poorer preservation and shorter occupation. The recovery of few
plant-food remains in rim samples, coupled with a complete lack of such
remains in the hearth of the tested kiva, suggests that foods were rarely
prepared in the rim complex. The greater-than-expected richness of wood-charcoal
types, on the other hand, indicates that a variety of woods were used
in this part of the site. The rim complex may have been a location where
public activities involving the serving of food prepared elsewhere at
the pueblo, as well as the burning of a greater-than-usual variety of
wood, were conducted.
80
The inhabitants of Woods Canyon Pueblo used many of the same plants during
both the early and late periods of occupation. A greater-than-expected
number of total food and fuel taxa in the samples from the canyon bottom
suggests that the early occupants had access to, or perhaps simply preferred,
a greater variety of plants than did later occupants. We cannot, however,
rule out differential preservation as a contributing factor to the observed
pattern. Juniper appears to have been the primary fuelwood through time.
By the later occupation, use of pine as fuel decreased, possibly because
of the slow recovery of depleted pine stands, whereas the use of sagebrush
for fuel increased, possibly because this shrub flourishes in fallow agricultural
fields.
81
The people of Woods Canyon Pueblo appear to have farmed fields
close to their village, as evidenced by the recovery of pieces of corn
stalks and cobs in samples collected from the site. As judged by the relative
proportions of corn and weedy plants to hardier, less-desirable, and higher-cost
foods, significant food stress does not appear to have occurred at the
pueblo. Seasonal availability of plant resources, coupled with inferences
about agricultural scheduling needs, together suggest that the village
was occupied at least from spring through fall; winter habitation was
likely as well. Generally, the people of Woods Canyon Pueblo used many
of the same plant resources that are available in the area surrounding
the site today.
Acknowledgments
Much of the text of this chapter is derived from an
early version of my senior honors thesis at the University of North Carolina
at Chapel Hill, supervised by Margaret Scarry and Karen R. Adams. I am
grateful to them and to my committee of readers, Vincas Steponaitis and
Richard Yarnell. Vandy Bowyer, Donna Glowacki, Keith Kintigh, Scott Ortman,
R. Lee Rainey, Virginia Rainey, Christopher Rodning, Dylan Schwindt, and
Amber Van der Warker provided helpful comments and suggestions. The Crow
Canyon Archaeological Center and Michael Kolb provided computing resources
along the way. Finally, I would like to thank Melissa Churchill and Mark
Varien, the principal investigators of the Woods Canyon project, for allowing
me to work on this report and for their advice and encouragement during
the course of the project.
Katharine D. Rainey
1In this chapter, we refer to several types of refuse, or trash: Primary refuse is trash that was left at the place where it was generated (Schiffer 1987*1:58). Secondary refuse is trash that was disposed of away from the place where it was created, usually into a midden (Schiffer 1987*1:58). Crow Canyon researchers distinguish between two types of secondary refuse. In situ secondary refuse is still in the place where it was originally discarded; naturally redeposited secondary refuse is trash that has moved from its original position as the result of erosional processes such as wind, water, and gravity.
Copyright © 2002 by Crow Canyon Archaeological Center. All rights reserved.