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Cultural Resource ManagementExcavations at the Arroyo de la Presa SiteThe Center, through a subcontract with the Center for Archaeological Research of the University of Texas at San Antonio, conducted both testing (May 2000-Archeological Testing at Sites 41PS800 and 41PS801, Presidio County, Texas) and mitigation (January-March 2001) excavations at the Arroyo de la Presa site (41PS800) in southern Presidio County. Initiated prior to reconstruction and rehabilitation of Farm-to-Market (FM) Road 170, the project was sponsored by the Environmental Affairs Division of the Texas Department of Transportation. The site is located on several terraces along the Rio Grande between the communities of Redford and Presidio, Texas. Placed along the relatively narrow highway right-of-way on the uppermost of these terraces, the investigations provided data on a number of prehistoric occupations at the site dating between approximately A.D. 700-1650. While testing indicated the presence of potentially significant archeological deposits and the need for more extensive excavations, it was not until the mitigation phase that the true character of the site deposits were realized. The stratigraphy at the site proved to be very complex (see profile), partially a result of past surfaces having been eroded and cut by channels from a nearby tributary drainage. Most of the deposits observed at the site were fine sands laid down by overbank flood waters of the river. In all, a total of eight stratigraphic units or zones were delineated across the upper portion of the site. One of these zones, Zone IV, proved to contain the most concentrated prehistoric deposits uncovered, roughly dating to the period A.D. 700-1250. The next highest zone, Zone III, also contained appreciable cultural deposits that appear to date between A.D. 1250-1600. All of the 13 archeological features uncovered at the site are thought to have been constructed and used during formation of one of these two zones. Most substantive archeological work in the past along this stretch of the Rio Grande (which is included within the area known archeologically as the La Junta district) has focused on several kinds of sites dating to the approximate period of A.D. 1200-1700: 1) village sites on terraces along the river (the La Junta phase and the Concepcion phase), and 2) hunter-gatherer sites positioned on high adjacent pediments (the Cielo complex). While a great deal is known about those site types, the recent work at the Arroyo de la Presa site has provided important chronological and behavioral data for another kind of site from this period, a hunter-gatherer site immediately next to the river. Findings from the site help fill in some of the gaps in our understanding of use of this environment through the latter portions of prehistory. Radiocarbon and botanical analyses, in tandem with other findings from the site, have allowed these inferences. The Arroyo de la Presa site is an open campsite occupied primarily by hunter-gatherers, although some findings suggest that members of nearby villages also may have conducted activities there at times. It should be noted that the radiocarbon data presented below are calibrated (2-Sigma) dates or ranges (Talma and Vogel 1993; Struiver and van der Plicht 1998; Struiver et al. 1998). Depth limitations for the highway project precluded an effort to completely delineate all past occupations. However, we know that around 3,000 years ago (1060-880 B.C.) prehistoric Native Americans apparently constructed at least one burned rock feature at the site. Burned rock and chipped stone debris scattered from erosion attest to this ephemeral occupation. During the Late Prehistoric period (ca. A.D. 700-1535), agave, yucca, or sotol hearts were apparently being processed at the site in a large earth oven or ovens. Evidence of this activity come from the recovery of small fibers in several features. This processing activity occurred during the beginning of the period (A.D. 660-860) as well as several other times (A.D. 880-1020 and A.D. 1040-1260)-it probably occurred on a regular basis, but these are the only dates associated with these findings. Since only small fibers were preserved, it is unknown which of these plants are actually represented. Rock-lined pits served as "ovens" in these endeavors-the succulent hearts were placed in the pits along with brush, grass, and wood. The combustibles were ignited, the oven covered, and the hearts allowed to slowly cook over a period of several days. Historic documentation of this process indicates the hearts were sun-dried after being recovered from the oven, ground into a flour-like matrix, mixed with water, and ultimately made into edible cakes (Greer 1965:51). These types of features, which first appeared in the archeological record in this region during the Late Archaic period (ca. 1000 B.C.-A.D. 700) and persisted into the late nineteenth century, are widely spread across the Trans-Pecos region of Texas. Small, stone-lined hearths were being used at the site during the first portion of the Late Prehistoric period (A.D. 780-1020), and perhaps earlier and/or later. These hearths may have been used for cooking or warming, or perhaps both purposes; however, the lack of associated animal bones or plant residues suggests they may have only been used for warmth. Four such hearths have been uncovered at the site and all date to this relatively narrow window of time. One of the most informative features excavated at the site was a pit measuring over 2 m (6.5 ft) in diameter that contained a wide variety of material goods and botanical remains (see photo). Interpreted as a trash pit and dated to the middle portion of the Late Prehistoric period (A.D. 1040-1260), this pit has provided a great deal of behavioral data. Within it were burned remnants of plants that appeared to have been processed as foodstuffs: agave, yucca, or sotol fibers, saltbush seeds, mesquite beans, and goosefoot or pigweed seeds. Small burned bones from the pit, most of which appeared to be from rodents (at least one large lizard was represented), provide additional dietary information for this time. A burned rock pavement at the site, apparently constructed about the same time as the trash pit (A.D. 1040-1290) and measuring over 2 x 4 m (6.6 x 13.1 ft), appears to have been used to parch mesquite beans. Burned mesquite pods and seeds were the only potential plant foodstuffs recovered from this feature. Mesquite and saltbush wood was apparently placed on a sloping ground surface, ignited, then covered with a pavement of river cobbles 2-3 courses thick. It is thought that the mesquite beans were parched on the upper surface of this pavement. Ethnographic documentation of mesquite processing in the American Southwest indicates that after being parched the beans were typically pounded into flour with a mortar and pestle (Felger 1977; Rea 1997). The function of several different pit features at the site was not as discernable. One of these had a slight bell-shape, a diameter of about 65 cm (25.6 in), and contained four clustered burned rocks on its base. This feature provided a date of A.D. 780-980, but lacked botanical remains. Three other pits with unknown functions were dated to the end of the Late Prehistoric period or to the subsequent Protohistoric period (A.D. 1420-1650; A.D. 1420-1490; and A.D. 1420-1800). What appeared to be a large pit loosely filled with burned rock yielded evidence of prickly pear processing. Several burned fruit fragments and a burned seed recovered from its matrix attest to this activity. Based on our understanding of the stratigraphy at the site, this feature most likely dates from about A.D. 1250-1600. The only artifacts recovered during the investigation that supply information relative to the time period of their manufacture, arrow points (see photo) and ceramic sherds, support the radiocarbon dates obtained from the features at the site (i.e., the Late Prehistoric period-ca. A.D. 700-1535). The earliest arrow points found adhere to the Livermore type, a type long suspected as being the first or one of the first arrow points that were used in the region-one of these points was uncovered up against a small piece of charcoal that yielded a date of A.D. 690-890. This is the earliest known date for Livermore points in the region, and it agrees with the time period that J. Charles Kelley initially, then later proposed for the Livermore phase-A.D. 800-1200 (Kelley et al. 1940:163) and A.D. 900-1200 (Kelley 1957:51). However, since this point and the dated charcoal were not within a cultural feature, the association may be fortuitous. Other arrow points and arrow point fragments recovered consist of several other Livermore and Livermore-like fragments, three Toyah or Toyah-like specimens, four small, untyped side-notched specimens, an untyped corner-notched specimen, the aforementioned specimen with both Livermore and Perdiz attributes, a Perdiz point, and several probable Perdiz point fragments. In general, the different point styles suggest that a number of different groups used the site, although any one group may have utilized several different types during a single occupation. It is likely that both Livermore phase and La Junta phase peoples are represented by these arrow points. Only five ceramic sherds have been recovered from the site and these appear to represent two different pottery types (Jornada Brown and an untyped/unknown brownware), neither of which are well-documented in the region. Although previous work has suggested pottery did not appear until about A.D. 1200 in this portion of the Trans-Pecos-in association with the La Junta phase (Kelley et al. 1940), the untyped sherd could date as early as A.D. 700-900 based on its stratigraphic position within the site deposits. Also found at the site were stream-rolled pebbles bifacially-notched on opposing ends, artifacts previously only documented in riverine archeological contexts (Kelley et al. 1940; Cloud et al. 1994; Mallouf 1999). These notched pebbles, which have been interpreted as weights for fishing nets, were found vertically distributed at the site indicating use through time. Interestingly, fish bones were not found in any of the features or excavation units, possibly suggesting this resource, if exploited, was cooked and eaten in another portion of the site or a different locale altogether. Several of the items recovered are materials or are made from materials that do not occur naturally in the immediate area, suggesting trade played a role in their presence. Included among these exotic items are an extremely shiny metallic pebble thought to be zinc, a discoidal stone bead most likely made of serpentine or serpentinite, and an Olivella sp. shell. Both of the stone items were probably from distant sources, such as areas of New Mexico and/or Central Texas, where outcrops of these materials are known to exist, while the shell appears to be of a species endemic to the Pacific coast of Mexico. One or more of these items may have passed through Casas Grandes, a major redistribution center in northern Chihuahua thought to have had influences on the La Junta area during the Late Prehistoric period (Kelley 1990; Mallouf 1999). Most of the findings from the site agree with our understanding of hunter-gatherer activities and tool kits in the region. However, some of the pit features, the ceramics, and the possible trade items are suggestive of a presence at the site by more sedentary folks, perhaps small groups from nearby agricultural villages procuring selective resources along this stretch of the river. Indications are that most of the features in use at the site were constructed to process specific plant foodstuffs, while evidence of hunting, trapping, or fishing were relatively minimal. The site has provided the first indication in this portion of the region of saltbush seed, sacaton grass seed, and goosefoot or pigweed seed exploitation. Furthermore, the botanical data from the site has provided indications of occupations during different seasons of the year-spring (agave, sotol, or yucca processing), late spring/early summer (sacaton grass seed processing), and mid- to late-summer (goosefoot or pigweed, mesquite bean, saltbush seed, and prickly pear fruit processing). In retrospect, the data recovered at the site has greatly strengthened our understanding of human ecology along the river during the Late Prehistoric period, allowing specific feature types to be much better understood in both temporal and behavioral terms. Additional analyses are currently planned for select materials from the site, so check this page in the future for an update. References Cited 2003 - Archeological Survey of the Proposed 102-Mile Six Shooter to Midland Airport Fiber Optic Cable, Pecos, Crockett, Upton, and Midland Counties, Texas. Reports in Contract Archeology 8, Center for Big Bend Studies, Alpine. |
Interestingly, no fish remains or tools associated with fishing were found in the pit despite the location of the site along the river. Other items recovered from this feature include a faceted hematite pebble, 35 ground stone fragments, an arrow point with attributes of both the Livermore and Perdiz types, an etched pebble, and a fossil fragment (Turritella sp.). The etched pebble is an unusual item not previously documented in this portion of the region (see photo).
One of these was extremely intact, suggesting that it had been intentionally covered shortly after being used. This circular pit had a diameter of about 1.1 m (3.6 ft), a depth of at least 50 cm (19.7 in), and contained what appeared to be digging stick marks along one of its sides and in portions of its base. The areas of the base that lacked these marks contained well-preserved charcoal "logs" (see photo) that were identified as mesquite, cottonwood/willow, and saltbush. A couple of burned pigweed or goosefoot seeds in the lower fill of the pit may indicate what was being processed. Another of these pits also had charcoal lining its base and was found to contain a few burned sacaton grass seeds. Whether these specific plant seeds were parched within these respective pits or were fortuitous additions is unknown at this time.