Rio Puerco Research Articles

Micaceous Mindsets: Chemical characterization of classic period utility wares at multiple sites along the Rio Grande

Micaceous utility wares are commonly found at Ancestral Pueblo villages in the Rio Grande region, yet they have received relatively little attention compared to contemporary glaze wares. This lack of attention is unfortunate, because utility wares were a common component of daily Pueblo activities and are shown to have been involved in complex exchange schemes. Neutron activation analysis is used to chemically characterize micaceous utility sherds recovered from seven Classic Period (AD 1300–1600) sites located along the Rio Puerco and Rio Grande between the modern towns of Santa Fe and Socorro, New Mexico. The resulting distribution patterns broadly indicate heterogeneous procurement and/or manufacturing practices from site-to-site over the three centuries examined; however, a shared distribution between the Rio Puerco and Central Rio Grande is distinguishable. This relationship is evaluated and interpreted under a communities of practice framework, and bears to question how the manufacture, distribution, and use of micaceous utility wares elsewhere may be explored with this approach.

Can biological soil crusts be prominent landscape components in rangelands? A case study from New Mexico, USA

To sustainably manage rangelands, it is paramount that all agents of soil health are considered in conservation practices. Yet, our understanding of the extent and importance of biological soil crust (hereafter biocrust) as a component of rangeland health and quality is limited. The objective of this project was to quantify and characterize rangeland biocrusts within a region of New Mexico, USA, for which soil microbes have yet to be considered in rangeland health assessments: the Rio Puerco Watershed. Moreover, we examined the influence of biocrust on soil aggregate stability as key ecosystem service in a landscape prone to erosion. We further assessed the relationships between biocrust abundance and community composition with soil properties. We found that biocrusts covered an average of 41% of plant interspaces throughout all sampling locations (n = 20), with the most abundant types being incipient and light cyanobacterial crusts, which tend to be more cryptic in appearance. Soil surface stability was greater than subsurface stability and biocrust cover was positively related to soil surface stability. Light cyanobacterial and cyanolichen crusts were the primary biocrust types related to soil surface stability, especially on sites with unconsolidated subsurfaces. Physical soil crusts were also a major landscape component covering an average of 21% of the soil and were important for subsurface stability. These findings reflect the importance of biological and physical soil aggregating processes in dryland systems. Several environmental variables were related to biocrust community composition and aggregate stability, with surface soil texture, salt contents, pH, and soil nitrogen ions having the strongest relationships. This study expands the biocrust characterizations of drylands in a region that has received little attention. It further contributes new insights on how biocrust and soil microbial communities may play a role in influencing rangeland health, providing much needed data for a watershed characterized by its high susceptibility to soil loss.

Effects of melting, subduction-related metasomatism, and sub-solidus equilibration on the distribution of water contents in the mantle beneath the Rio Grande Rift

The distribution of water in the upper mantle plays a crucial role in the Earth's deep water cycle, magmatism, and plate tectonics. To better constrain how these large-scale geochemical systems operate, peridotite and pyroxenite mantle xenoliths from Kilbourne Hole (KH) and Rio Puerco (RP) along the Rio Grande Rift (NM, USA) were analyzed for water, and major and trace element contents. These xenoliths sample a lithosphere whose composition was influenced by subduction and rifting, and can be used to examine the effects of melting, metasomatism, and sub-solidus equilibration on the behavior of water. The first result is that in KH xenoliths, olivines underwent negligible H loss during xenolith ascent, i.e. preserved their mantle water contents. These olivine water contents are used to calculate mantle viscosities of 0.5–184 · 1021 Pa·s. These viscosity values are more than 40 times higher than those of the asthenosphere and show that KH peridotites represent samples from the lithosphere. The preservation of olivine water contents is exceptional for off-cratonic xenoliths, and the KH peridotites provide the first estimate of the average concentration of water in Phanerozoic continental mantle lithosphere at 81 ± 30 ppm H2O. The mantle lithosphere beneath the Rio Grande rift is nevertheless heterogeneous with water contents ranging from <0.5 to 120 ppm H2O in peridotites and from 227 to 400 ppm H2O in pyroxenites. A composite KH xenolith of a harzburgite cross-cut by a clinopyroxenite vein shows this heterogeneity at the cm scale. The second contribution of this study stems from the majority of the KH peridotites and two of the RP peridotites having major and trace elements that can be explained by partial melting without any need to invoke metasomatic processes. This allows to show that, prior to modelling the water content variation of each peridotite mineral during melting, a correction for sub-solidus equilibration has to be applied to the water contents of the minerals. Sub-solidus equilibration also provides an explanation for the discrepancy between the clinopyroxene/orthopyroxene ratio of water contents in natural peridotites worldwide and in laboratory experiments on water partitioning in peridotite minerals. Finally, the cryptically metasomatized peridotites, rare at KH and abundant at RP, as well as the pyroxenites, permit to decipher the origin and water contents of the metasomatic melts that affected the continental lithosphere beneath the Rio Grande Rift. Trace element modelling of the metasomatized KH and RP peridotites are consistent with metasomatism via melts that are of subduction origin. Melts in equilibrium with peridotites contain more water at RP (∼1 wt.% H2O) than at KH (∼0.5 wt.% H2O), although this did not result in a more water-rich mantle lithosphere at RP. Rio Puerco lies within the northern Rio Grande rift, proposed to have been affected by a flat slab subduction, which may explain the more hydrous and extensive metasomatism compared to the south, where KH is located.

Geomorphic processes responsible for decadal-scale arroyo changes, Rio Puerco, New Mexico

Geomorphic processes responsible for decadal-scale arroyo changes, Rio Puerco, New Mexico

Wastelanding: Legacies of Uranium Mining in Navajo Country

In this sophisticated and insightful book, Traci Brynne Voyles argues that the process of “wastelanding” helps explain the history and persistence of environmental injustice. Environmental racism stems not only from constructed discourses of race but also from constructed conceptions of place. Asserting their colonial dominance over the Navajo, Euro-Americans defined indigenous lands in the American Southwest as wasted and useless, making those landscapes, and the people who inhabited them, pollutable. Wastelanding enabled the development of uranium mining and milling on Navajo land, a continuation of the colonial project with dramatic, if slowly evolving, violence inflicted on both the land and people. “The power exerted over environmental resources,” Voyles explains, “and the ways in which those in power construct knowledge about landscapes, are a central part of how what we now call social injustices are produced” (p. ix). In exploring the legacy of uranium mining in Navajo country, Voyles draws from tremendously powerful histories: the forced sterilization of indigenous women paired with the reproductive health impacts of radiation exposure; Navajo houses constructed from radioactive uranium mill tailings; and the virtually unknown Rio Puerco accident in 1979, when the containment barriers of a tailings pond in New Mexico failed and sent a radioactive slurry into the river and through reservation lands—the largest accidental release of radioactive material in American history. From these and other stories Voyles builds a convincing case for connections between colonialism, wastelanding, and environmental injustice. She brings her account to the present by examining grassroots activism regarding land tenure, environmental health, and the prospect of renewed uranium mining, underscoring her historical argument by demonstrating the ongoing link between the demands for decolonization and justice.

Early Navajo land use in northwestern New Mexico: Big Bead Mesa in regional perspective

Big Bead Mesa (LA 12351) is the most famous Navajo archaeological site ever investigated and has played an important role in the interpretation of Navajo culture history. It remains a sacred place to the Navajo, both for historical and spiritual reasons. Pioneering work by Dorothy L. Keur resulted in the publication of the first Society for American Archaeology Memoir and brought Navajo archaeology national recognition. James Hester used Big Bead Mesa as the type site for his Cabezon Phase, although he conducted no research at the site. Big Bead Mesa is not the only Early Navajo site in the Rio Puerco Valley; however, the surrounding area has never been adequately investigated or reported. This paper documents a variety of Navajo sites in the Rio Puerco Valley and indicates that Big Bead Mesa was only a small part of a much larger Navajo occupation that extended to the north, west, and south.

Implications for Migration and Social Connections in South-Central New Mexico Through Chemical Characterization of Carbon-Painted Ceramics and Obsidian

Magdalena Black-on-white ceramics from two sites (Gallinas Springs and Pinnacle Ruin) in west-central and southwestern New Mexico have been interpreted as evidence of a migration of Northern Pueblo groups from the Four Corners region into southwestern New Mexico during the thirteenth century. They also appear to be linked to sites with similar carbon-painted ceramics on the Rio Puerco of the east and beyond. An additional site (Roadmap Village) reveals import of Magdalena Black-on-white ceramics produced at Gallinas Springs as well as possible local production. Limited quantities of carbon paint ceramics have been found on El Paso Phase sites in south-central New Mexico that have previously been attributed to contemporaneous carbon-painted pottery produced at communities in the Galisteo Basin and the upper Rio Grande. Recent compositional analysis of carbon-painted ceramics from the Gallinas Springs, Pinnacle, and Roadmap sites has identified characteristic chemical signatures that suggest local production of carbon paint ceramics at all three sites and distribution of carbon paint ceramics from Gallinas Springs to Pinnacle and Roadmap in the eastern Black Range of southwestern New Mexico. Analysis of carbon paint ceramics from Madera Quemada, an El Paso Phase site in the Tularosa Basin indicates that the carbon paint wares found in El Paso Phase sites were acquired through trade connections from the Black Range rather than from more northern sources. The overall Magdalena Black-on-white production patterns are contrasted with the obsidian procurement data from the same sites to reveal a complex and divergent pattern.

Aquatic Invertebrate and Vertebrate Communities of Ephemeral Stream Ecosystems In the Arid Southwestern United States

Abstract Ephemeral streams in the southwestern United States have unpredictable, short, torrential flows during extreme weather, and their aquatic biology is poorly studied. During the 2006 monsoon, we sampled aquatic communities at 14 ephemeral stream sites within the Santa Cruz River, Arizona, and Rio Puerco, New Mexico, watersheds following a monsoon-related thunderstorm and continuing daily until flows and pools dried. With the 86 taxa of macroinvertebrates that we collected, these sites host a modest community, although presence was limited by drying. Macroinvertebrate taxa richness was not associated with duration of water presence, and biomass was greater in sites with less water available. We collected more taxa in ephemeral reaches of interrupted streams than in truly ephemeral streams. Drought-resistant/resilient species traits were well represented. Vertebrates colonized these ephemeral stream reaches quickly; however, native fish species used ephemeral reaches as corridors between perennial re...

Processes of arroyo filling in northern New Mexico, USA

We documented arroyo evolution at the tree, trench, and arroyo scales along the lower Rio Puerco and Chaco Wash in northern New Mexico, USA. We excavated 29 buried living woody plants and used burial signatures in their annual rings to date stratigraphy in four trenches across the arroyos. Then, we reconstructed the history of arroyo evolution by combining trench data with arroyo-scale information from aerial imagery, light detection and ranging (LiDAR), longitudinal profiles, and repeat surveys of cross sections. Burial signatures in annual rings of salt cedar and willow dated sedimentary beds greater than 30 cm thick with annual precision. Along both arroyos, incision occurred until the 1930s in association with extreme high flows, and subsequent filling involved vegetation development, channel narrowing, increased sinuosity, and finally vertical aggradation. A strongly depositional sediment transport regime interacted with floodplain shrubs to produce a characteristic narrow, trapezoidal channel. The 55 km study reach along the Rio Puerco demonstrated upstream progression of arroyo widening and filling, but not of arroyo incision, channel narrowing, or floodplain vegetation development. We conclude that the occurrence of upstream progression within large basins like the Rio Puerco makes precise synchrony across basins impossible. Arroyo wall retreat is now mostly limited to locations where meanders impinge on the arroyo wall, forming hairpin bends, for which entry to and exit from the wall are stationary. Average annual sediment storage within the Rio Puerco study reach between 1955 and 2005 was 4.8 × 10 5 t/yr, 16% of the average annual suspended sediment yield, and 24% of the long-term bedrock denudation rate. At this rate, the arroyo would fill in 310 yr.

“CEREMONIAL ROOMS” AT POTTERY MOUND, NEW MEXICO

Excavations at Pottery Mound, a Pueblo IV site on the Rio Puerco south of Albuquerque, New Mexico, exposed three types of rooms: kivas, domestic rooms for both habitation and storage, and “ceremonial rooms.” One of the last was sealed and contained ceremonial artifacts. Others were rooms whose internal features (and possibly also artifacts) differed from those of kivas and domestic rooms. The presence of “ceremonial rooms” at Pottery Mound may have to do with its probable multi-ethnic composition, or perhaps with the transformation of lineage-based to sodality-based ritual and social organization in the Eastern Pueblo world.

Efflorescence as a source of hydrated sulfate minerals in valley settings on Mars

A distinctive sulfur cycle dominates many geological processes on Mars and hydrated sulfate minerals are found in numerous topographic settings with widespread occurrences on the Martian surface. However, many of the key processes controlling the hydrological transport of sulfur, including sulfur sources, climate and the depositional history that led to precipitation of these minerals, remain unclear. In this paper, we use a model for the formation of sulfate efflorescent salts (Mg–Ca–Na sulfates) in the Rio Puerco watershed of New Mexico, a terrestrial analog site from the semiarid Southwest U.S., to assess the origin and environmental conditions that may have controlled deposition of hydrated sulfates in Valles Marineris on Mars. Our terrestrial geochemical results (δS34 of −36.0 to +11.1‰) show that an ephemeral arid hydrological cycle that mobilizes sulfur present in the bedrock as sulfides, sulfate minerals, and dry/wet atmospheric deposition can lead to widespread surface accumulations of hydrated sulfate efflorescences. Repeating cycles of salt dissolution and reprecipitation appear to be major processes that migrate sulfate efflorescences to sites of surface deposition and ultimately increase the aqueous SO42− flux along the watershed (average 41,273 metric tons/yr). We suggest that similar shallow processes may explain the occurrence of hydrated sulfates detected on the scarps and valley floors of Valles Marineris on Mars. Our estimates of salt mass and distribution are in accord with studies that suggest a rather short-lived process of sulfate formation (minimum rough estimate ∼100 to 1000 years) and restriction by prevailing arid conditions on Mars.

Effects of woody vegetation on overbank sand transport during a large flood, Rio Puerco, New Mexico

Distributions of woody vegetation on floodplain surfaces affect flood-flow erosion and deposition processes. A large flood along the lower Rio Puerco, New Mexico, in August 2006 caused extensive erosion in a reach that had been sprayed with herbicide in September 2003 for the purpose of saltcedar (Tamarix spp.) control. Large volumes of sediment, including a substantial fraction of sand, were delivered to the reach downstream, which had not been treated with herbicide. We applied physically based, one-dimensional models of flow and suspended-sediment transport to compute volume concentrations of sand in suspension in floodplain flow at a site within the sprayed reach and at a site downstream from the sprayed reach. We computed the effects of drag on woody stems in reducing the skin friction shear stress, velocity of flow, and suspended-sand transport from open paths into patches of dense stems. Total flow and suspended-sand fluxes were computed for each site using well-constrained flood-flow depths, water-surface slopes, and measured shrub characteristics. Results show that flow in open paths carried high concentrations of sand in suspension with nearly uniform vertical distributions. Drag on woody floodplain stems reduced skin friction shear stresses by two orders of magnitude, yet sufficient velocities were maintained to transport sand more than 50m into fields of dense, free-surface-penetrating stems. An increase in shrub canopy extent from 31% in the sprayed reach site to 49% in the downstream site was found to account for 69% of the computed decrease in discharge between the two sites. The results demonstrate the need to compute the spatial distribution of skin friction shear stress in order to effectively compute suspended-sand transport and to predict the fate of sediment and contaminants carried in suspension during large floods.

Effects of riparian vegetation on topographic change during a large flood event, Rio Puerco, New Mexico, USA

The spatial distribution of riparian vegetation can strongly influence the geomorphic evolution of dryland rivers during large floods. We present the results of an airborne lidar differencing study that quantifies the topographic change that occurred along a 12 km reach of the Lower Rio Puerco, New Mexico, during an extreme event in 2006. Extensive erosion of the channel banks took place immediately upstream of the study area, where tamarisk and sandbar willow had been removed. Within the densely vegetated study reach, we measure a net volumetric change of 578,050 ± ∼ 490,000 m3, with 88.3% of the total aggradation occurring along the floodplain and channel and 76.7% of the erosion focusing on the vertical valley walls. The sediment derived from the devegetated reach deposited within the first 3.6 km of the study area, with depth decaying exponentially with distance downstream. Elsewhere, floodplain sediments were primarily sourced from the erosion of valley walls. Superimposed on this pattern are the effects of vegetation and valley morphology on sediment transport. Sediment thickness is seen to be uniform among sandbar willows and highly variable within tamarisk groves. These reach‐scale patterns of sedimentation observed in the lidar differencing likely reflect complex interactions of vegetation, flow, and sediment at the scale of patches to individual plants.

Evaluation of a Steel Girder Bridge Collapse during Deck Removal

The evaluation of a welded, steel girder bridge that once crossed the Rio Puerco River near Albuquerque, New Mexico, is presented in this study. Following 44 years of service, the bridge was scheduled for total replacement due to the poor condition of the structure. On May 18, 2011, the bridge girders collapsed due to lateral torsional buckling during removal of the concrete deck, resulting in a few injuries but luckily no loss of life. The buckling resistance of the compression flange of the steel girders was evaluated. Dead load and live load effects were determined from three-dimensional analyses. The results presented herein show that the deck removal procedure was not structurally sound and the compression-flange flexural capacity was exceeded in the exterior girder due to inadequate bracing, which initiated the bridge collapse. Following buckling of the exterior girder, load redistribution to the remaining girders resulted in demand versus capacity ratios exceeding 1, and ultimately progressive collapse of the entire bridge.

Erosion, storage, and transport of sediment in two subbasins of the Rio Puerco, New Mexico

Arroyos in the American Southwest proceed through cut-and-fill cycles that operate at centennial to millennial time scales. The geomorphic community has put much effort into understanding the causes of arroyo cutting in the late Quaternary and in the modern record (late 1800s), while little effort has gone into understanding how arroyos fill and the sources of this fill. Here, we successfully develop a geographic information system (GIS)–modeled sediment budget that is based on detailed field measurements of hillslope and channel erosion and deposition. Field measurements were made in two arroyo basins draining different lithologies and undergoing different land disturbance (Volcano Hill Wash, 9.30 km 2 ; Arroyo Chavez, 2.11 km 2 ) over a 3 yr period. Both basins have incised channels that formed in response to the late nineteenth-century incision of the Rio Puerco. Large volumes of sediment were generated during arroyo incision, equal to more than 100 yr of the current annual total sediment load (bed load + suspended load) in each basin. Downstream reaches in both arroyos are presently aggrading, and the main source of the sediment is from channel erosion in upstream reaches and first- and second-order tributaries. The sediment budget shows that channel erosion is the largest source of sediment in the current stage of the arroyo cycle: 98% and 80% of the sediment exported out of Volcano Hill Wash and Arroyo Chavez, respectively. The geomorphic surface most affected by arroyo incision and one of the most important sediment sources is the valley alluvium, where channel erosion, gullying, soil piping, and grazing all occur. Erosion rates calculated for the entire Volcano Hill Wash (–0.26 mm/yr) and Arroyo Chavez (–0.53 mm/yr) basins are higher than the modeled upland erosion rates in each basin, reflecting the large contributions from channel erosion. Erosion rates in each basin are affected by a combination of land disturbance (grazing) and lithology—erodible sandstones and shales in Arroyo Chavez compared with basalt for Volcano Hill Wash. Despite these differences, hillslope sediment yields are similar to long-term denudation rates. As the arroyo fills over time from mouth to headwaters, hillslope sediment becomes a more significant sediment source.

Modeling Road Erosion in Upper Torreon Wash, New Mexico

Accurate prediction of sediment detachment, transport, and delivery from dirt road networks is an expensive and time-consuming task. The Water Erosion Prediction Project (WEPP) model allows users to predict road erosion on the basis of specific characteristics including road length, width, and gradient. The WEPP:Road model is tailored to specific climate conditions, road design, and unique attribute information. The methodology was applied to unpaved roads in the upper Torreon Wash located in northwestern New Mexico. Torreon Wash serves as a tributary to the Rio Puerco River, which gained worldwide attention because of extremely high erosion rates. This study incorporates results from the WEPP:Road model to determine the impact of erosion on the described area. Main roads and access routes within the study area were evaluated to determine the estimated sediment delivery from unpaved roads. The analysis was specifically targeted to identify areas of intense erosion and sediment delivery to stream systems and included a case study to determine the effects of past remediation efforts. Remediation work consisted of 110 rolling dips that were installed on roads, and findings suggest that remediation efforts can reduce road erosion by 48%. Results showed that reducing sediment loads from unpaved roads decreased sediment delivery to stream networks by 27%, creating a positive impact on nearby streams.

Holocene alluvial sequences, cumulic soils and fire signatures in the middle Rio Puerco basin at Guadalupe Ruin, New Mexico

AbstractWe describe a geoarchaeological survey of a 5‐km reach of the Rio Puerco channel and its tributaries, centered on the Guadalupe Ruin, a pueblo of the late 10th–12th centuries A.D. in north‐central New Mexico, with associated pollen, charcoal, micromorphological, and radiocarbon analyses. Severe erosion has drastically bisected the Puerco valley with four primary arroyos entering the western side of the Guadalupe reach of the valley: Tapia, Salado, Guadalupe and “No Name.” We recorded an 11‐m‐tall alluvial sequence marked by four phases of cumulic soil development, interrupted by six major periods of channel entrenchment that occurred at about 4100–3700 B.C. and 2900–2400 B.C., between 2200 B.C. and ca. A.D. 400, pre‐ and post‐ca. A.D. 900–1300, and in the late A.D. 1800s. Relative floodplain stability and associated cumulic soil development occurred prior to ca. 5700 B.C., between ca. 2600 to 2200 B.C. and A.D. 350 and 550, and ca. A.D. 900–1300. Multiple signatures of fires (oxidized sediment and charcoal) were observed in the Arroyo Tapia tributary sequence, especially in deposits dated ca. 6000 and 2600 B.C. These fires may have helped to enhance food resources for game animals by encouraging grass and shrub growth and/or to increase the growth of wild plants and eventually cultigens such as maize. Palynological evidence of maize in the Arroyo Tapia, dated ca. 2600–2200 B.C. may be the earliest thus far identified in the Southwest. © 2009 Wiley Periodicals, Inc.

Erosional Consequence of Saltcedar Control

Removal of nonnative riparian trees is accelerating to conserve water and improve habitat for native species. Widespread control of dominant species, however, can lead to unintended erosion. Helicopter herbicide application in 2003 along a 12-km reach of the Rio Puerco, New Mexico, eliminated the target invasive species saltcedar (Tamarix spp.), which dominated the floodplain, as well as the native species sandbar willow (Salix exigua Nuttall), which occurred as a fringe along the channel. Herbicide application initiated a natural experiment testing the importance of riparian vegetation for bank stability along this data-rich river. A flood three years later eroded about 680,000 m(3) of sediment, increasing mean channel width of the sprayed reach by 84%. Erosion upstream and downstream from the sprayed reach during this flood was inconsequential. Sand eroded from channel banks was transported an average of 5 km downstream and deposited on the floodplain and channel bed. Although vegetation was killed across the floodplain in the sprayed reach, erosion was almost entirely confined to the channel banks. The absence of dense, flexible woody stems on the banks reduced drag on the flow, leading to high shear stress at the toe of the banks, fluvial erosion, bank undercutting, and mass failure. The potential for increased erosion must be included in consideration of phreatophyte control projects.

Magnitude and duration of surface uplift above the Socorro magma body

We use interferometric synthetic aperture radar and geomorphic data to constrain the magnitude and duration of uplift driven by the magma body beneath Socorro, New Mexico, United States. Interferometry spanning 1992–2006 confirms uplift of the Socorro magma body at a rate of ~2.5 mm/yr. However, we find no clear evidence for volcanic uplift after an examination of three rivers (Rio Salado, Rio Puerco, Rio Grande), and two terraces (Llano de Manzano, Llano de Albuquerque) crossing the Socorro magma body. Our geomorphic measurements permit at most 25–50 m of cumulative surface uplift above the Socorro magma body since the middle Pleistocene, but require no long-term uplift. Given previously articulated thermal arguments for the Socorro magma body, we therefore suggest either a recent (within the last few centuries) initiation of uplift at Socorro, or that long-term uplift and subsidence have been essentially equal.

The Ritual Importance of Birds in 14th-century Central New Mexico

Abstract The Pueblo IV period (AD 1300–1450/1500) in the American Southwest witnessed the development of a number of new ritual systems in both the Western and Eastern Pueblo areas. Although associated with a diverse array of material culture, one of the most prominent aspects of these religious ideologies was the adoption of a complex of icons focusing on fertility, weather control, and community well being. Key among these motifs were birds, which appear to have played a central role in the materialization of these new ideological systems. In this paper, we evaluate the changing importance of avifauna in the ritual systems that were adopted in the 14th century in the Lower Rio Puerco area of New Mexico. Relying on ceramic, architectural, and faunal data from Pottery Mound (LA 416) and Hummingbird Pueblo (LA 578), we argue that both the imagery and use of birds in ritual contexts increased substantially at the two villages during the 14th century. These developments correspond to a new religious ideology...