1

Bedrocks Metates along the Chaquaqua Drainage: Building a Conceptual Frameworkof Prehistoric Landscape Knowledge

ABSTRACT: The canyons and tributaries of the Purgatoire River in Southeastern Colorado

reveal evidence of continuous and seasonal occupation of Indigenous peoples for thousands of

years. Evidence abounds for habitation by plains hunter gatherers, horticulturalists and

possibly ancestral woodland culture groups. A unique feature of this regional system is the

presence of numerous types of bedrock metates occurring at varying elevations and site

assemblages. This paper addresses a critical and understudied problem: how prehistoric

peoples in this region incorporated bedrock grinding features within their socio-cultural view

of the landscape. Photogrammetry and GIS are used to develop and explore a regional spatial

distribution of these features at the intra-site and inter-site level.

Bedrock Grinding Features and Southern Plains Archaeology

Bedrock grinding areas (generally classified as metates, mortars and slicks) are an

integral part of the prehistoric landscape in southeastern Colorado and northeastern New

Mexico (Figure 1). They are generally located among the canyon sidewalls and rock

outcrops east of the Rocky Mountains, south of the Arkansas River and north of the

Cimarron River in northern New Mexico and eastern Oklahoma. Reported within site

descriptions from this region since Renaud (1931), the densest concentration appears to be

along the canyon sidewalls of the Chacuaco, Apishapa and Purgatoire Rivers and their

tributaries (Campbell 1969; Loendorf 2008; Owens 2007). The waterways cut through the

plains and mesas in a complex maze which eventually connect with the Arkansas River

(Campbell 1969; Fenneman 1931; Gunnerson 1989). Bedrock grinding features were

generally created along the sandstone rims and ledges of the canyons, though others have

been found among the ubiquitous rock art boulders of the basalt strewn formation known

2

as the Hogback near Trinidad, Colorado (Andrefsky 1990; Campbell 1969; Chomko and De

Vore 1990; Gunnerson 1989; Hartley and Vawser 2003; Loendorf 2008; Renaud 1931).

Archaeology in the region reveals a complex array of lifeways and subsistence

patterns from the remains of lithic, grinding tools, architecture and ceramic artifacts

although bedrock grinding features are difficult to place within the archaeological context

(Campbell 1969; Eighmy 1984; Zier et al 1999). There is sparse ethnographic

corroboration of their use within the region. Unlike their portable or site-fixed

counterparts, bedrock grinding features are permanent on the landscape leaving them

exposed to a variety of erosional forces. This permanence is important in creating a

perspective of landscape. At present there are few reliable methods to directly date these

surfaces or to assess functionality through pollen or starch analysis. Temporal claims are

based on association with surrounding features such as hearths, rock art and structures, or

on diagnostic projectile points found in associative context (Campbell 1969; Chomko and

De Vore 1990; Loendorf 2008). The few bedrock grinding surfaces that have been dated,

either with cation ratio techniques or by context with other diagnostics, are thought to date

from the late Archaic about 2000 RCYBP to about RCY500 BP (Campbell 1969; Chomko and

De Vore 1990; Loendorf 2008; Owens 2007). Since there is no historic record of the use of

these features, it appears that these features ceased to be used by the time Athapaskan

speakers appeared in the region at some point during the late 14th or 15th century

(Campbell 1969; Gunnerson 1989; Hammond and Rey 1940; Owens 2007; Stoffle 1984;

Zier et al 1999).

Bedrock Grinding Stations and Social Landscapes

3

Bedrock grinding features, like other permanent cultural features, such as

architecture, have the potential to inform past social dynamics between people and their

environment, as well as the role this relationship may have had within their symbolic

framework. What we understand about groundstone is generally from a functional view

point (Adams 2002; Buonasera 2007; Perry 2004) or related to subsistence strategies

(Bender 1990; Diehl 1996; Wright 1994). However, bedrock grinding features are

particularly useful in viewing social landscapes; especially how peoples gathered in order

to process and prepare staple foods (Holmberg 1998; Parkman 1994; Villalobos-Boehm

1997). Grinding at fixed locales for large groups or for bulk resource processing was often

done in large family groups or were community level grinding events (Adams 1999;

McCarthy et al 1985; Parkman 1994; Scroth 1996) though grinding on bedrock surfaces

has also been recorded at the family or individual household level (O'Connell et al 1991).

Signatures of these social processes remain on the landscape long after the grinders and

their communities have disappeared.

Studies of bedrock mortars in California have provided intriguing insight into the

socioeconomic relationship between prehistoric communities and their landscape as well

as providing evidence for seasonal movement across the landscape (McCarthy et al 1985;

Morgan 2008; Parkman 1994; True et al 1979). As fixed points on the landscape, bedrock

grinding features transform physical localities into places with meaning and social

significance and provide an organizational framework of the landscape. I advance the

argument that the permanent grinding places can be viewed landscapes themselves, work

spaces that were imbued with meaning, personal and social. Unlike the features in

California and elsewhere in the world, there is little ethnographic reference to help

4

decipher the meaning of the grinding places in the southern plains. However the physical

evidence that remains can be explored with current technology to offer some insight into

the prehistoric grinding landscape of the southern plains.

Working the Problem

The problem, in developing a method to explore prehistoric landscape perception

through these bedrock grinding surfaces, centers on building a linking argument between

function of grinding places and the meaning of grinding places. With no regional

ethnography or consistent recording of features within an archaeological context to assist,

the model foundation becomes the individual grinding surfaces themselves. The grinding

stations must be defined within their unique, individual context along with the natural and

archaeological landscape in which they are located. The goal is to construct grinding

landscape in the sense of a taskscape (Ingold 1993). This will establish a base relationship

between these surfaces and the environment. Thus the grinding stations become the basic

element of the socio-cultural landscape.

Bedrock grinding features are not, however, independent of their environs. How

then to model that particular landscape which may include other archaeological features

(rock art, grinding features, structures, rock shelters, etc.) as well as the nearby natural

resources. Since the both the temporal sequence and functional nature of the grinding

stations are uncertain at this time, I have decided to view each bedrock feature as

independent of site data (see Morgan 2008:248). Site boundaries are often arbitrarily

assigned or decided by natural slope or breaks in the landscape such as streams, drainages,

or elevation. This may distort inferences about feature context, obscuring the meaning

imbued in, or functional nature of, the work areas.

5

Independent recording the individual features in a defined area refines our

knowledge of the actual landscape features or landscape artifacts present in any given area

across this region. The separation of the grinding features from the construct of “site”

means that I can define the nature of each grinding feature as an organized landscape, or

work space, confined to the environ of a particular boulder or exposed bedrock area. Using

photogrammetry to model this surface area, I can generate digital terrain models to

compare, statistically and visually, individual grinding areas to one another. Then, by

recording the surrounding archaeological features and artifacts within a select parameter, I

can build an area specific map that will compare the grinding features found within that

area to one another, as well as to nearby archaeological features or artifacts and to natural

resources also found within that area. If grinding use and wear are indications of

demographics, long term use and/or materials being ground then I should be able to build

a baseline model of the workspaces and how they fit into the landscape in with they are

situated (Adams 1999; McCarthy et al 1985; Morgan 2008; Nelson and Lippmeier 1993;

Parkman 1994; Schneider 1993). I will describe the preliminary and rough results of a

study which has revealed the dynamic and complex nature of the bedrock grinding work

space (Lynch et al 2007).

A Working Case Study

Clustered bedrock features along the Chaquaqua (Chacuaco), are found in many

different environmental settings but appear to be confined to the cliffs along the canyon

systems. To explore these complex site areas, we began with a simple question: do the rock

art panels found in association with bedrock metates inform the grinding workspace? We

chose a site was that had work spaces which could be quantified with photogrammetry,

6

buried metates which could yield dateable artifacts, and rock art. The presence of rock art

could provide a temporal window, since it is well seriated for this region, as well as a

cultural or social context. We operated under assumption that the rock art and the grinding

workspace were contemporaneous (Lynch et al 2007).

Site 5LA11455 is a small rockshelter with a single bedrock workstation and a pecked

abstract motif along an adjacent boulder (Loendorf 2008). The rockshelter is about 10

meters below the rim and opens to the east overlooking the Chaquaqua waterway about

200 meters down slope (Figure 2). The bedrock grinding surface is on a large sandstone

boulder which dominates the shelter (Figure 3). There are four main workstations each

comprising a large, deep, oval-shaped basin oriented perpendicular to a shallower oblong

basin metate (Figure 3). Workspace was cramped. The ceiling of the shelter is about one

meter above the grinding surface. Two metates were filled with sediment and protected by

a rat midden so there was potential to extract datable and identifiable material (Loendorf

2008; Lynch et al 2007).

The physical landscape, in which these sites are located, is rough terrain; not easily

accessed from above or below. The site was confined to the shelter (rock art and bedrock

metates) and the terrace in front of the shelter (Loendorf 2008). However, while recording

the site for this study, we located another bedrock grinding station to the south of this

shelter and third grinding station along the ridge just above as well as two other areas

within twenty-five meters of the site. None of these other areas had been recorded. The

grinding areas were not in rock shelters and, though different in shape and wear pattern,

they may have been used in association with 5LA11455. This illustrates the dilemma faced

when trying to sort out use and landscape perception of these grinding features.

7

The presence of rock art panels at a number of these grinding sites (and others

along the Chacuaco) raises intriguing questions about the imagery and its’ meaning or role

within the site context. But in the absence of regional specific ethnographic evidence – how

can we understand the site relationships? For the purpose of that inquiry we decided to

approach the site, panels and metates surfaces, as an integrated site component in a

“domestic context” (Quinlan and Woody 2003:375). Assuming a direct association

between the two main components: rock art panels and groundstone, it is possible to infer

that the work space had significance to the prehistoric inhabitants of the space (Bachelard

1969; Ingold 1993; Tuan 1977). It seemed likely that we could learn more about who was

the intended audience then who actually created the panels by looking at the workspace

itself (Loendorf 2008).

The results of the study provided limited but intriguing insight into the work space.

Comparing the rock art to other sites in the region indicated that the panel almost certainly

dated to the Diversification Period and may represent an extended range of occupation or

multiple visits between AD1050 – AD1450 (Loendorf 2008:72). The rock art panel is about

two meters above the ground surface and is visible from bedrock grinding station but not

so visible from the rock shelter opening. Could this mark identify the grinders? Is there a

similar pattern at other stations? Would it help determine why grinding was done here?

The use of photogrammetry to define the workspace provided information that has

enormous potential for groundstone research. I will briefly describe the procedures we

used to build a model of this grinding workspace. Using a Canon EOS camera I

photographed overlapping images along the surface area (Breithaupt et al 2004; Matthews

2008; Matthews et al 2006). This yielded hundreds of images of the surface (Figure 4).

8

These images were used in a 3D measure and modeling software package for

photogrammetric analysis. Three-dimensional model of the surface and the digital image

dataset was generated. This model can be rotated to better visualize the grinding surface

(Figures 5, 6). Digital terrain data generated from the stereoscopic images were generated

to show topographic contours (Figure 7). This process can better define feature

morphology, generate data for intra-feature analysis, and cross feature analysis, to infer

functional relationships between individual grinding surfaces.

The Next Step

The process described above generates analyzable data that can be used

independently to analysis grinding areas or can be employed with Geographic Information

Systems (GIS) to build a prehistoric landscape model for the southern plains. The first step

in this process is to begin recording the bedrock grinding features, neighboring

archaeological features or artifacts and groundtruthing the local vegetation. Once these

data are entered into GIS we can begin to tease out the patterns, if any exists, of design,

locality and temporality. It is precisely the existence or absence of these archaeological

patterns that will chronicle the prehistoric social-cultural landscape of this region.

9

References Cited

Adams, Jenny L.1999 Refocusing the Role of Food-Grinding Tools as Correlates for Subsistence Strategies in the U.S.

Southwest. American Antiquity 64(3):475-498.

2002 Ground Stone Analysis : A Technological Approach. University of Utah Press, Salt Lake.

Andrefsky, William1990 An Introduction to the Archaeology of Pinon Canyon, Southeastern Colorado. 5 vols. Fort Collins,

Co., Laramie, Wyo. : Larson-Tibesar Associates.

Bachelard, Gaston1969 The Poetics of Space / Uniform Title: Poétique De L'espace. English. Beacon Paperback. Beacon

Press, Boston.

Bender, Marilyn1990 Chapter X: Groundstone Analysis. In An Introduction to the Archaeology of Pinon Canyon,

Southeastern Colorado edited by William Andrefsky, pp: 1-43. Larson-Tibesar Associates andCentennial Archaeology. National Park Service Rocky Mountain Regional Office InteragencyArchaeological Services, Denver.

Breithaupt, Brent , Neffra Matthews and Tommy Noble2004 An Integrated Approach to Three-Dimensional Data Collection at Dinorsaur Tracksites in the

Rocky Mountain West. Ichnos 11:11-26.

Buonasera, Tammy2007 Investigating the Presence of Ancient Absorbed Organic Residues in Groundstone Using Gc-Ms

and Other Analytical Techniques : A Residue Study of Several Prehistoric Milling Tools fromCentral California. Journal of Archaeological Science 34(9):1379-1390.

Campbell, Robert Gordon1969 Prehistoric Panhandle Culture on the Chaquaqua Plateau, Southeast Colorado. Ph.D.

dissertation, University of Colorado, Boulder.

Chomko, Stephen A. and Steven L. De Vore1990 Sorenson Prehistoric Fortifications (Sites 5la330 and 5la331) : An Apishapa Village on the

Purgatoire River. Interagency Archeological Services, Rocky Mountain Regional Office, NationalPark Service, Denver, Colo.

Diehl, Michael W.1996 The Intensity of Maize Processing and Production in Upland Mogollon Pithouse Villages A.D.

200-1000. American Antiquity 61:102-15.

10

Eighmy, Jeffrey L.1984 Colorado Plains Prehistoric Context for Management of Prehistoric Resources of the Colorado

Plains. Office of Archaeology and Historic Preservation, Colorado Historical Society, Denver.

Fenneman, N. M.1931 Physiography of the Western United States. McGraw-Hill, New York.

Gunnerson, James H.1989 Apishapa Canyon Archaeology Excavations at the Cramer, Snake Blakeslee, and Nearby Sites

Reprints in Anthropology 41. J & L Reprint Company, Lincoln.

Hammond, George P. and Agapito Rey1940 Narratives of the Coronado Expedition, 1540-1542. Coronado Cuarto Centennial Publications,

1540-1940 II. University of New Mexico Press, Albuquerque.

Hartley, Ralph J. and Anne M. Wolley Vawser2003 Rockshelters, Rock Art, and Grinding Activity: A Preliminary Assessment of Relationships in

Picket Wire Canyonlands, Comanche National Grasslands. Midwest Archaeological CenterNational Park Service.

Holmberg, Cecilia Lidström1998 Prehistoric Grinding Tools as Metaphorical Traces of the Past. Current Swedish Archaeology

6:123-142.

Ingold, Tim1993 The Temporality of the Landscape. World Archaeology 25(2):152-174.

Loendorf, Lawrence2008 Hunting, Grinding, and Dancing: Petroglyph Sites on the J.E. Canyon Ranch, Southeastern

Colorado. Colorado Rock Art Association, Colorado Historical Society.

Lynch, Elizabeth M., Matthews Neffra and Lawrence Loendorf2007 Imagery and the Landscape of Workspace: Exploring Techniques to Define the Relationship

between Rock Art and Groundstone. Presented at the Plains Conference, Laramie Wyoming.

Matthews, Neffra A.2008 Resource Documentation, Preservation, and Interpretation: Aerial and Close-Range

Photogrammetric Technology in the Bureau of Land Management. U.S. Department of theInterior, Bureau of Land Management, National Operations Center.

Matthews, Neffra A. , Tommy A. Noble and Brent H. Breithaupt2006 The Application of Photogrammetry, Remote Sensing and Geographic Information Systems

(Gis) to Fossil Resource Management. In Fossils from Federal Lands, edited by J.A. SpielmannS.G. Lucas, P.M. Hester, J.P. Kenworthy, and V.L. Santucci. New Mexico Museum of NaturalHIstory and Science Bulletin 34, Denver.

11

McCarthy, Helen, Robert A. Hicks and Clinton M. Blount1985 A Functional Analysis of Bedrock Mortars: Western Mono Food Processing in the Southern

Sierra Nevada as Appendix F. In Cultural Resources of the Crane Valley Hydroelectric Project,Madera County, California, pp. 303-356. Pacific Gas and Electric Company, San Francisco.

Morgan, Christopher2008 Reconstructing Prehistoric Hunter-Gatherer Foraging Radii: A Case Study from California's

Southern Sierra Nevada. Journal of Archaeological Science 35(2):247-258.

Nelson, Margaret C. and Heidi Lippmeier1993 Grinding-Tool Design as Conditioned by Land-Use Pattern. American Antiquity 58(2):286-305.

O'Connell, James F. , Kristen Hawkes and Nicholas Blurton-Jones1991 Distribution of Refuse-Producing Activities at Hadza Residential Base Camp: Implications for

Analysis of Archaeological Site Structure. In The Interpretation of Archaeological SpatialPatterning, edited by Ellen Kroll and T. Douglass Price, pp. 58-76. Plenum Press, New York.

Owens, Mark2007 A Model for Predicting Late Prehistoric Architectural Sites at the Pinon Canyon Maneuver Site in

Southeastern Colorado. Directorate of Environmental Compliance and Management, Fort Carsonand the National Park Service, Midwest Archaeological Center. Ft. Belvoir Defense TechnicalInformation Center.

Parkman, E. Breck1994 The Bedrock Milling Station. In The Ohlone Past and Present: Native Americans of the San

Francisco Bay Region, edited by Lowell John Bean, pp. 43-63. Ballena Press, Menlo Park.

Perry, Linda2004 Starch Analysis Reveal the Relationship between Tool Type and Function: An Example from the

Orinoco Valley of Venezuela. Journal of Archaeological Science 31:1069-81.

Quinlan, Angus R. and Alanah Woody2003 Marks of Distinction: Rock Art and Ethnic Identification in the Great Basin. American Antiquity

68(2):372-390.

Renaud, E. B.1931 Archaeological Survey of Eastern Colorado. University of Denver, Denver.

Schneider, Joan S.1993 Milling Implements: Biases and Problems in Their Use as Indicators of Prehistoric Behavior and

Paleoenvironment. Pacific Coast Archaeological Society Quarterly 29(4):5-22.

Scroth, Adella B.1996 An Ethnographic Review of Grinding, Pounding, Pulverizing, and Smoothing with Stones. Pacific

Coast Archaeological Society Quarterly 32(4):55-75.

12

Stoffle, Richard W.1984 Toyavita Piavuhuru Koroin = Canyon of Mother Earth : Ethnohistory and Native American

Religious Concerns in the Fort Carson-Pinon Canyon Maneuver Area : Final Report. University ofWisconsin--Parkside, Kenosha.

True, D. L., M. A. Baumhoff and J. E. Hellen1979 Milling Stone Cultures in Northern California: Berryessa I. Journal of California and Great Basin

Anthropology 124-54.

Tuan, Yi-fu1977 Space and Place : The Perspective of Experience. University of Minnesota Press, Minneapolis.

Villalobos-Boehm, Susan1997 An Analysis of 201 Bedrock Grinding Features in Utah's Grand Gulch Primitive Area. M.A. Thesis,

University of Colorado, Boulder.

Wright, Katherine I.1994 Ground-Stone Tools and Hunter-Gatherer Subsistence in Southwest Asia: Implications for the

Transition to Farming. American Antiquity 59(2):238-263.

Zier, Christian J. , Stephen M. Kalasz and Mary W. Painter1999 Colorado Prehistory : A Context for the Arkansas River Basin. Prehistory of Colorado, a

Publication Series;. Colorado Council of Professional Archaeologists, Denver, CO.

13

Figures

Figure 1. Map showing the approximate location of the Chaquaqua Plateau. (Images E.Lynch)

Figure 2. Rockshelter 5LA11455 located above the Chacuaco Creek in SoutheasternColorado. (Image: Elizabeth Lynch)

14

Figure 3. The workspace at 5LA11455 and the adjacent rock art panel. (Images: LarryLoendorf and Elizabeth Lynch in (Lynch et al 2007))

Figure 4. Image depicting the camera positions from which stereoscopic(overlapping) images were taken. These images were used in a 3D measureand modeling software package for photogrammetric analysis. (Image:Neffra Matthews In (Lynch et al 2007))

Figure 5. 3D model of the surface and the digital image dataset rotated tobetter visualize surface features.2007))

Figure 6. Cross section of grinding artifact. (Images: Neffra Matthews. In2007))

Figure 7. Digital terrain model of the bedrock surface. (Images: Neffra Matthews inet al 2007))

15

3D model of the surface and the digital image dataset rotated tobetter visualize surface features. (Images: Neffra Matthews In (Lynch et al

Figure 6. Cross section of grinding artifact. (Images: Neffra Matthews. In

ure 7. Digital terrain model of the bedrock surface. (Images: Neffra Matthews in

3D model of the surface and the digital image dataset rotated to(Lynch et al

Figure 6. Cross section of grinding artifact. (Images: Neffra Matthews. In (Lynch et al

ure 7. Digital terrain model of the bedrock surface. (Images: Neffra Matthews in (Lynch