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Show PREHISTORIC BEDROCK MORTARS IN SOUTHEASTERN UTAH Matthew J. Landt and Jenn Mueller; Department of Anthropology, Washington State University, Pullman, WA 99165 Four bedrock mortars have recently been located at two sites ( 42Sa22846 and 42Em3127) on lands managed by the Bureau of Land Management ( BLM) in southeastern Utah. With a few exceptions, southeastern Utah is a poorly researched area where archaeological evidence of Fremont and Great Basin peoples is interwoven with evidence of Northern Anasazi and American Southwest occupations. These bedrock mortars are located in the . edge of pinyon- juniper plant communities on low- angle bedrock, directly adjacent to sagebrush and grassland pats. The bedrock mortars are found in sites with long- term occupations that span the mid- to terminal Archaic. INTRODUCTION Bedrock grinding features, both metates and mortars, are common throughout the American Southwest and Great Basin. Although bedrock mortars are common throughout much of the southern and western portions of North America in California ( Wlodarski 1982), New Mexico ( Pick 1999), Texas ( Boyd 2002; Kirkpatrick 1978; Shawn 1971), and Mexico ( Boyd 1996,2002), they are unreported from sites in southeastern Utah. Mortars tend to be typologically associated with the processing of specific plants, as with acorns in California ( Wlodarski 1982) and mesquite seedpods across the lower Southwest ( Schneider 1996). In the same sense, metates and grinding implements in the American Southwest tend to be associated with the processing of corn ( personal communica-tion, John Jones 2004). However, it is implicit in all instances that mortars are also utilized to process any number of edible plant parts into flour, and process small animal bone into meal ( Osbourne 1998). The fact that mortars ' are useful in processing a wide array of items in the general subsistence system of prehistoric peoples suggests that they might be spread more widely across the landscape than is currently reported in the literature. Stone mortars are time intensive to create, whether fashioned directly with a specific final form in mind, or by repeated use of a convenient natural depression ( Osbourne 1998). Heavy time and energy investments during the creation and use- life of bedrock mortars suggests that many subsistence items were gathered in the nearby environment, and brought to an often visited processing location. As such, the location and utilization of bedrock mortars in prehistoric subsistence systems is telling regarding the continuity and productivity of provi- Utah Arclmology 17: 3.3- 45. 2204 [. an& and Mrcelier - Redrock ~ Wortaars sions in nearby environments. Thus, the building of mortars into exposed portions of bedrock indicates landscape loci where prehistoric people would return on a regular, if not predictable, basis for subsistence needs. It is therefore important to note that four bedrock mortars have been recently located at two sites on lands administered by the BLM in southeastern Utah. The following portion of this report is dedicated to descriptions of the mortars as well as the sites they are found on. The site descriptions include preliminary environmental and cultural/ temporal information gleaned from surface survey data. That is followed by an abbreviated discussion regarding the role that non- portable resource processing equipment may have played in the subsistence systems of diverse groups of prehistoric peoples. The reporting and future analysis of bedrock mortars in southeastern Utah is important for archaeological research in an area that was a prehistoric patchwork of cultural identities. SITE 42SA22846 Site 42Sa22846 was first recorded in the mid- 1990s during a development project survey and revisited in 2004 by archaeologists employed by the Bureau of Land Management ( BLM) - Moab Field Office ( MFO). Site 42Sa22846 is located in the southeastern portion of Utah, south of the La Sal Mountains between Moab and Monticello, at an elevation of 6,500 feet. Surrounding the site are mesas, incised canyons and linear cliffs that are characteristic of the Utah portion of the ~ oioradoPl ateau and the Paradox Basin ( Black et a1 1981; BLM 1997). Most of the local rainwater run- off is short- lived and stream flow is intermittent. Permanent water can be currently found at two springs or seeps located two, two- and - a- half and kilometers from the site. Erosional channels cut through many portions of the landscape, with shallow gullies and washes along the mesatops, benches and ridges, while deep arroyos cut 10- 20 feet through portions of the valley floor. The mostly alluvial soils in the valley range from loamy clay to sandy gravel, and tend towards moderate to strong alkalinity ( BLM 1997). Today, sediment on the valley floor and gentle bottom slopes supports low sagebrush communities interspersed with rabbitbrush, wheat- grass and Indian ricegrass. Site 42Sa22846 sits along a northeast- to- southwest running finger ridge that protrudes onto the valley. Mixed pinyon and juniper woodland dominates on the finger ridge as well as on the steeper valley slopes and mesa tops. Of particular note at 42Sa22846 is a pair of round bedrock mortars ( Figure 1) located 2.13 m apart. The mortars are built into a sandstone outcrop on the northwest facing edge of the finger ridge. The southern mortar has an average diameter of 25.5 cm, is 8 cm deep and has a U- shaped bottom ( Figure 1B). The northern mortar has an average diameter of 34.5 cm, and is 11 cm deep with a U- shaped bottom ( Figure 1A). The northern mortar has an eroded bedrock crack running across its center, which currently acts to drain precipitation from the bowl's center. Sloping grooves along the internal walls and the relatively rough bottom ( as compared to the grinding Litah Archaeology 20004 3 5 surface of metates) of the two mortars are suggestive of both the use- wear and original construction of the grinding features ( Figure 1A & B) ( Osbourne 1998). It is likely that the mortars were constructed by pecking and hammer-ing at the original sandstone outcrop to create a depression. That depression was then continually enlarged andlor deepened during its use- life by the pounding and circular grinding motions of plant and animal processing. Site 42Sa22846 contains a diverse lithic assemblage that includes projectile points, bifaces, groundstone, bedrock mortars, multiple concentrations of lithic debitage, and dispersed oxidized sandstone that is suggestive of hearths onsite. The largest lithic concentration was located towards the middle of the site on a small knob between two ephemeral washes and contained the majority of artifacts including an end- battered cobble, 3 diagnostic points including a re- sharpened San Jose point ( 4,000 - 1,500 B. C.), the basal fragment of a Durango Notched point ( 2,500 - 400 B. C.) and a San Pedro point ( 1,500 - 300 B. C.) ( Justice 2002). Although jasper of varying quality is available in the local canyon system, most of the lithic debitage material is from non- local sources. While no structural evidence exists on the surface of the landform for habitation of the site other evidence including the presence of labor intensive grinding features, dense lithic scatters and a diverse array of lithic tools are reminiscent of other habitation sites in southeastern Utah ( Pollock 2001, Richens and Talbot 1989). Further, site 42Sa22846 is located within 200 meters of numerous other sites on the same finger ridge, some of which contain slab- lined hearths, middens and the remains of a pinyon nut cache. Any temporal association between the multiple sites on the finger ridge is speculative, as none of the sites have been excavated. However, the tight cluster and high number of sites on the small finger ridge are suggestive of high subsistence productivity in the local environment throughout the past. SITE 42EM3127 After the identification of bedrock mortars at site 42Sa22846, BLM- Moab Field Office archaeologist D. Turnipseed directed the authors to two additional bedrock mortars recently noted in Emory County, UT. Site 42Em3 127 was originally recorded and mitigated in 2003- 2004 by Grand River Institute as part of a BLM devel-opment project. Site 42Em3127 is located west- northwest of Moab between Hanksville and Green River at an elevation of 5,280 feet. Topographically the area around site 42Em3127 is typical of the exposed low- angle bedrock and mixed grassland plains of southeast Utah located along the San Rafael Reef. Although seasonal run-off is short lived and numerous shallow gullies and washes cross the landscape, permanent water can be found at a nearby springlseep located less than one kilometer from the site. Site 42Em3127 sits at the base of an exposed southeast facing bedrock slope that terminates on the fringes of a large alluvial- filled valley currently overlaid with aeolian dunes. A sparse population of dwarf pinyon- juniper interspersed with ephedra and blackbrush surrounds 36 Ian& and iWurRer - Bedrock iWorturs the site. The soils directly adjacent to the site support sparse short sagebrush, antelope brush, and bitterbrush communities in a grassland environment dominated by rabbitbrush, wheat- grass and Indian ricegrass, The mortars are built about 88 m apart from each other, in sandstone outcrops at the base of the exposed bedrock slope, along and within a modern erosional channel. The southern- most basin is 36 cm in diameter and has a U- shaped bottom that is 5.7 cm deep ( Figure 2B). The northern- most mortar averages 36 cm in diameter and is 9 cm deep with a U- shaped bottom ( Figure 2A). There are no internal grooves along the walls of either mortar although large pecking marks are evident on the bottoms of both. This is suggestive of the type of manufacture and the use- life of these mortars ( Osbourne 1998) with less grinding and more pounding of the subsistence items . than seen at site 42Sa22846. Further indications of mortar use are evident in modification of the adjacent bedrock at site 42Em3127 where either kneelinglstanding and/ or the brushing of meal back into the mortar have worn a subtle smooth band around each mortar. The outer edge of the worn area is indicated by arrows in Figure 2A & B and is further evidence of the long- term usage of both the mortars and the area. Previous surface surveys of site 42Em3217 identified subsurface hearths, a semi- subterranean slab- lined feature identified as a possible pithouse, dense lithic scatters and a diverse array of lithic tools. The artifact assemblage noted during the original site survey includes 3 Fremont ceramic sherds, 4 projectile points dating from the mid to late Archaic ( includes one identified Gypsum point), bifaces, groundstone, and multiple large lithic concentrations. Recovered materials from Grand River Institute's limited excavations include radiocarbon dates and bulk soil samples that are currently being analyzed and documentation is forthcoming ( personal communica-tion, Carl Connor 2004). The alluvial- filled valley and nearby permanent water source are both likely to have contributed to a highly productive grassland environment that was utilized on a regular basis by prehistoric peoples of the area. Site 42Em3 127 is part of a large sprawl of sites that line the edge of the San Rafael Reef. Finalization of the excavation analyses and report will substantially assist in defining the temporal affiliation of this site as well as providing additional information regarding the role of the bedrock mortars in the subsistence strategy of the sites inhabitants. BEDROCK MORTAR UTILIZATION Both bedrock mortar sites in are located at the base of mesa and hill slopes, near drainages and alluvial1 aeolian soils in transitional ecological zones between pinyon- juniper woodlands and mixed sage- grassland flats. Since mortars can be used to efficiently process a wide array of plant and animal resources, the placement of non-portable subsistence processing equipment in areas of potentially high and/ or mixed prehistoric environmental resource productivity is suggestive of their diverse role in past resource systems. For example, Indian ricegrass ( Achnatherum hymenoides) and Colorado Pinyon Pine ( Pinus edulis) nuts are currently available in the environs directly adjacent to both sites. Although Indian ricegrass is certainly more prevalent at the Emory county site grasses may have been more common prehistorically around 42Sa22846 than the modern environment suggests since the current nature of the dominant sagebrush community is likely a product of modern chaining and seeding regimes as well as wild fire suppression that broke the cyclical nature of prehistoric grassland - sagebrush plains ( Winter and Hogan 1986). Ethnographic accounts of pinyon nut processing suggests that very shallow slab metates were used for gently removing the hulls of previously roasted nuts ( Madsen 1986), although the use of mortars in grinding the pinyon nuts into flour is also noted ( Fowler 1986). Dwarf oaks are found in the vicinity of site 42Em3127 ( personal communication, Carl Connor 2004) and those bedrock mortars may have been utilized to process acorns in the same manner as acorns are processed in California and the western edge of the Great Basin ( Fowler 1986; Wlodarski 1982). Grasses abound on the stable aeolian dunes next to site 42Em3127 and agave is prevalent on stable aeolian dunes on the mesa- top immediately above site 42Sa22846. While agave may or may not have been processed in the bedrock mortars, stable aeolian dunes are also one of the ideal locations for incipient agriculture and some Basketmaker I1 habitations are situated to effectively utilize these dune environs for dry farming ( Matson et al. 1988). The bedrock mortars found in southeastern Utah are morphologically distinct from bedrock grinding features in Mesa Verde associated with the processing of corn. Corn grinding features tend to be longer than they are wide and generally rectangular in appearance. These bedrock trough metates associated with corn agricultur-ists have been examined in the scores by researchers ( personal communication John Jones 2004) and are often shiny, polished and smoothed from the back and forth motion of corn grinding. While it is unlikely that the bedrock mortars at sites 42Em3127 and 42Sa22846 were utilized for processing corn it should be noted that corn has been radiocarbon dated at a site just east of 42Sa22846 during the late Archaic at 160 B. C. ( Jett 1991). The above narrative is in no way intended as an exhaustive or comprehensive list of subsistence items that were processed in the bedrock mortars. Rather the description is meant to illustrate the usefulness of bedrock mortars placed in regularly productive transitional ecological zones. The full prehistoric utility of these four bedrock mortars should be approached through future palynological analyses. Botanical residues and prehistoric pollen from the bedrock mortars may be useful in reconstructing the prehistoric plant resource base as well as shaping our understanding of resources utilized by prehistoric people of the area as reliance on plant husbandry increases through time. As such, pollen washes of the two mortars at site 42Sa22846 are currently being analyzed by one of the authors. While the exposed environment in which the bedrock mortars are located may make the 38 I ~ n adnd Mueller - Bedrock Mortan recovery of botanical residues difficult, the rarity of these mortars in southeastern Utah suggests that such an undertaking may provide unique subsistence information for the region. PREHISTORIC OCCUPATION OF SOUTHEASTERN UTAH The bedrock mortar sites in southeastern Utah are situated in areas where a complicated interface between several cultural groups was articulated over time. While southeastern Utah has both Ancestral Puebloan and Fremont material remains ( Marwitt 1986; Geib et a1 2001; Huckell 1996; Jennings and Salmon- Lohse 1981), research has been far from conclusive about definitive patterns of interaction along the cultural interface between the different groups. Some sites indicate intermingled occupation by Fremont and Anasazi groups ( Jennings and Salmon- Lohse 1981; Madsen 1982) while other sites have remains more indicative of a single regional group whether that occupation was discontinuous or not ( Chandler 1990; Geib 1996, Lupo and Wintch 1998; Richens and Talbot 1989). In either case, complex patterns of migration and population movement are indicated by the occupations. These same patterns seem to be indicated in the areas farther north where research has been less intensive, although the majority of sites appear to follow lifeways more closely parallel to Great Basin cultural groups ( Marwitt 1986). The large roomblock pueblos typical of sedentary agricultural Anasazi peoples during Pueblo times to the south are not associated with site 42Sa22846, but the slab- lined hearths and dense scatters that can indicate Basketmaker I1 peoples are seen in the immediate area ( Mueller and Landt 2004; Pollock 2001; Richens and Talbot 1989). Site 42Em3127 is located in an area with prevalent Fremont and Great Basin cultural materials ( Geib et al. 2001). The discontinuity of cultural markers in the area and the lack of synthesized research to date make it difficult to place the bedrock mortars within any specific cultural milieu. While it seems fairly unlikely that bedrock mortars are strongly indicative of one particular cultural group or time period, these features are either frequently unnoticed by surveyors or are relatively unique in Utah, and thus their occurrence may be of import in unpacking the interface between different cultural groups. Both of these mortar sites are in places where discontinuous occupation was coupled with a diversifica-tion of food foraging strategies. Eastern Great Basin literature indicates that while food production was under-taken in some areas, such a strategy may have been frequently abandoned in favor of broad spectrum hunting and gathering strategies ( Jennings and Salmon- Lohse 1981). The potential resource failure associated with sedentary agricultural lifeways and dry- farming could be offset by diversifying resource procurement and utilization, particularly in areas where population densities were not so high as to have occupants locked into the landscape. This seems particularly true in regions of cultural overlap, where successful neighbors can serve as an example to groups who struggle with different resource strategies and thus provide an impetus for cultural change. Utah Arr! hacoiogy 2004 3 9 Figure 1: Photos of north ( A) and south ( B) mortar at site 42Sa22846 Figure 2: Photos of north ( A) and south ( B) mortar at site 42Em3127 Ilauh Arckaeoiogy 2004 CONCLUSIONS Four bedrock mortars have been located at two sites on lands administered by the BLM in southeastern Utah. Both sites are located in places that utilize bedrock outcrops immediately adjacent to large expanses of grassland and pinyon- juniper woodland, with ephemeral drainages located close- by and where permanent water sources are within walking distance. The mortars are thus located in transitional ecological zones where multiple plant food resources could provide the basis for a fully hunter- gatherer lifeway or as a complementary component of a full or partial agricultural lifeway. Because excavation at or near 42Sa22846 has not occurred and the excava-tions at 42Em3127 are still being analyzed, firm dates of the sites' occupation( s) have not been established. However, the large number of surrounding sites and the potentially long- term occupation of those sites are sugges-tive of the productivity of the local environment and the relative frequency of occupation through time. Bedrock metates are found throughout the Great Basin and Southwest areas at large, although the lack of reported round bedrock mortars in Utah appears to represent novel solutions to a diverse array of subsistence material processing problems. " Features, at whatever scale . . . not only provide a context for interpreting associ-ated artifact assemblages but also shed light on occupation patterns, site use and function, and subsistence tech-niques ( Shroedl and Coulam 1994: 4)." ' while four bedrock mortars are unlikely to unravel the complexities of group identity, their locations within both the ecological and cultural landscape are representative of larger occupa-tional patterns and subsistence strategies. As such, archaeologists are better able to consider larger scale cultural changes over time by including non- portable resource- processing equipment in examinations of the changing face of subsistence strategies. ACKNOWLEDGEMENTS Fieldwork was supported by BLM Cooperative Agreement # JSA045005. That grant and the fieldwork that followed would have been impossible without the assistance of Donna Turnipseed and Dr. Andrew Duff. Dr.' s William Lipe and John Jones are owed our gracious thanks for their invaluable support and consultations. 42 Landt and ~ lfatalle- r Bedrock .+ fortars REFERENCES Black, Kevin D., James M. Copeland and Steven M. Horvath Jr. 1981 An Archaeological Survey of the Central Lisbon Valley Study Tract in the Moab District San Juan County, Utah. In Contributions to the Prehistory of Southeastern Utah, edited by S. G. Baker, pp. 1- 188. Cultural Resource Series. vol. No. 13. Utah State Office, Bureau of Land Management, Salt Lake City. 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