Boca De Research Articles

Comparative study in stingless bees (Meliponini) demonstrates that nest entrance size predicts traffic and defensivity

Stingless bees (Meliponini) construct their own species-specific nest entrance. The size of this entrance is under conflicting selective pressures. Smaller entrances are easier to defend; however, a larger entrance accommodates heavier forager traffic. Using a comparative approach with 26 species of stingless bees, we show that species with greater foraging traffic have significantly larger entrances. Such a strong correlation between relative entrance area and traffic across the different species strongly suggests a trade-off between traffic and security. Additionally, we report on a significant trend for higher forager traffic to be associated with more guards and for those guards to be more aggressive. Finally, we discuss the nest entrance of Partamona, known in Brazil as boca de sapo, or toad mouth, which has a wide outer entrance but a narrow inner entrance. This extraordinary design allows these bees to finesse the defensivity/traffic trade-off.

Sujeitos no sumidouro: a experiência de criação e resistência do Jornal Boca de Rua

Este texto versa sobre o Jornal Boca de Rua, periódico confeccionado por moradores de rua da cidade de Porto Alegre. Procura-se nele relacionar a posição subversiva destes moradores de rua com a lógica do capitalismo contemporâneo em três instâncias - espaço urbano, mídia e consumo -, trabalhando seus detalhes, implicações, ambivalências e comentando seus resultados parciais. A resistência espacial é tida como a própria maneira do morador de rua habitar a urbe - seja como morador, seja como vendedor -, ou seja, a reinvenção dos desvalidos vãos da cidade. A resistência midiática, por sua vez, é caracterizada pela construção de um meio de dispersão alternativo ao mass-mídia, possibilitando a um grupo emitir palavras e imagens sobre si e fazê-las agenciáveis em circuitos antes não alcançados. A resistência do consumo, por fim, dá-se na possibilidade do deslocamento da posição de pedinte para a de prestador de serviço, o que, em última análise, possibilita outros modos de inserção do morador de rua nas tramas da sociedade atual.

The cinema of Eduardo Coutinho

Filming the word-in-act, the present events and the characters' uniqueness without proposing explanations or solutions, such are the principles of Eduardo Coutinho's cinema, plus another in his more recent works: filming in a demarcated space, in a specific favela (Santa Marta, Parque da Cidade, Babilônia), a garbage dump (Boca de Lixo), or an apartment building (Edifício Master). Spatial geography became essential to Coutinho's films, which imposes certain lines on what is to be filmed, immediately accentuating the immanent nature of the images produced by this film-maker. These principles make Eduardo Coutinho's cinema one of the present, but an impure present, not only that of actuality, but of remembrance or evocation.

The Agenda in situ

In this article, four prominent media professionals describe how the news agenda is elaborated in print, radio, television and internet journalism. Felipe Aldunate, editor of AméricaEconomía; Carola Urrejola, presenter of En Boca de Todos of Canal 13, Nibaldo Mosciatti, news director of Radio Bío Bío; and Doug Mitchell, director of Next Generation Radio, show what happen inside their respective workplaces, examining the journalistic mecha­nism and the editorial criterion behind their news selection process.

Metaphoric Commerce: The Greguerías novísimas and Their Circumstance

Metaphoric Commerce: The GreguerÃ-as novÃ-simas and Their Circumstance Juli Highfill is Associate Professor of Spanish at the University of Michigan , Ann Arbor. She has recently edited a collection on the economy of cultural production in Hispanic literature for the Journal of Interdisciplinary Literary Studies. She is the author o/Portraits of Excess: Reading Character in the Modern Spanish Novel (Society of Spanish and SpanishAmerican Studies 1999) and is currently working on a book manuscript entitled "The Vitality of Things: The Spanish Avant-Garde in Commodity Culture, 19181936 " where she explores the intersections of economics and literature. .. .hubo un momento en que la modernidad habló por la boca de Gómez de la Serna. (Octavio Paz 187) I. Exchanging Things Consisting of a single sentence or paragraph, ^greguerÃ-a is a small epiphany, a brief insrant of (mis)perception that brings two or more disparate objects into a surprising , humorous relationship of equivalence; hence, Ramon Gómez de la Sernas succinct definition for his invented genre: "metaphor + humor = greguerÃ-a?1 Ramon's metaphoric practice is extreme in that it manages to unite remote, seemingly unequivocal terms in a discordia concours, or similarity in dissimilare (Cardona 167).2 And across thousands of greguerÃ-as, the sheer quantity of these surprising analogies reaches a critical mass that works to reweave the web of relations among things. By means of this multi-associative capacity, observes Luis López Molina, "seres, objetos, aspectos, actitudes, acciones , funciones y comportamiento se mezclan, encabalgan, interpretan y sustituyen, produciendo las consecuencias más insólitas" (113). Consider a series of examples, proceeding from simple to more complex metaphorical structures—all drawn from NovÃ-simas greguerÃ-as (1929)3: Los canguros son los bolsistas del Parque Zoológico. (107) El automóvil que se exhibe en pleno relucimiento de aluminio es como una coctelera de las velocidades, las distancias y los peligros. (62) Arizona Journal of Hispanic Cultural Studies Volume 9, 2005 120 Arizona Journal of Hispanic Cultural Studies El volante de automóvil es el atril en que va la novela de lo por ver. (56) Los relojes eléctricos ponen inyecciones eléctricas al tiempo, ya caduco , arterioesclerótico y dispépsico. (102) In the first three greguerÃ-as, we find simple, explicit metaphorical structures in which a copula, the verb ser, establishes an equivalence between disparate terms. The equation in the first example, likening kangaroos to stock brokers, turns upon a mere pun on the term "bolsista." The second greguerÃ-a creates a metaphor based on the visual resemblance between a chrome-trimmed automobile and a cocktail shaker. But this visual similarity serves only as a point of departure for a more significant equivalence based on dynamic functions, for the auto-coctelero mixes cocktails of velocities, distances and dangers. In the third example, a condensed but equally dynamic greguerÃ-a, a steering wheel is equated with a lectern, which in turn suggests a second metaphor likening the ever-changing road-side to the moving pictures in a reader's mind. The final more complicated greguerÃ-a dispenses with the copula and leaves the series of equivalencies implicit: electric clocks (as doctors) inject electricity (as medicine) into an aged and sickly Father Time. Through hundreds of such absurd and ludic equations, the greguerÃ-as evoke a world gone awry, akin to Batailles vision of a "purely parodie" world: Ever since sentences started to circu- ¿zft? in brains devoted to reflection, an effort at total identification has been made, because with the aid of a copula each sentence ties one thing to another; all things would be visibly connected if one could discover at a single glance and in its totality the tracings of an Ariadne's thread leading thought into its own labyrinth. (5) Of course with tongue-in-cheek, Bataille is likening copula to copulation, and similarly , Ramon's greguerÃ-as exhibit en masse a palpable desire for unbridled miscegenistic couplings. Through their countless nonsensical equations, things enter inro commerce , swapping properties, trading places, or becoming other things. Ramón argued that an unfettered metaphorical practice was particularly pertinent to the modern age: La metáfora es, después de todo, la expresión...

Pre-Bomb Δ14C Variability and the Suess Effect in Cariaco Basin Surface Waters as Recorded in Hermatypic Corals

The Δ14C content of surface waters in and around the Cariaco Basin was reconstructed from radiocarbon measurements on sub-annually sampled coral skeletal material. During the late 1930s to early 1940s, surface waters within and outside of the Cariaco Basin were similar. Within the Cariaco Basin at Islas Tortugas, coral Δ14C averages −51.9 ± 3.3%. Corals collected outside of the basin at Boca de Medio and Los Testigos have Δ14C values of −53.4 ± 3.3% and −54.3 ± 2.6, respectively. Additional 14C analyses on the Isla Tortugas coral document an ∼11% decrease between ∼1905 (−40.9 ± 4.5%) and ∼1940. The implied Suess effect trend (−3%/decade) is nearly as large as that observed in the atmosphere over the same time period. If we assume that there is little to no fossil fuel 14CO2 signature in Cariaco surface waters in ∼1905, the waters have an equivalent reservoir age of ∼312 yr.

Time and space distribution and abundance of the fishes in the Cuyutlan Lagoon, Colima, Mexico

Monthly sampling in 21 sites in the Cuyutlán Lagoon, México were carried out from March toJune 1999 and October 1999 to December 2000, where 1,719 fish from 22 families were collected. The most abundant were: yellowfin mojarra (Gerres cinereus) with 43.86 %, white mullet (Mugil curema) in 24.89 %, mojarra (Diapterus peruvianus) with 6.34 %, Pacific thread herring (Opisthonema libertate) with 5.29 % and with 3 % Pacific crevalle jack (Caranx caninus) and longjaw leatherjack (Oligoplites altus). The specific richness changed from 3.52 in May 1999 to 15.48 in October 2000. The equitativity fluctuated from 0 in the 18th station named Palo Verde to 0.93 in the 20th site in the same area. The diversity index presented valuesfrom 0.33 in May 1999 to 1.06 in October 2000. By its physical and biological characteristics the lagoon can be divided into two different areas. The opening of the channel Boca de Tepalcates increased the diversity of species of fish, but it will take time to know how the biomass is going to change.

Heavy metals in the clam Tivela mactroides Born, 1778 (Bivalvia: Veneridae) from coastal localities with different degrees of contamination in Venezuela

We compared heavy metal levels (manganese, iron, zinc, cadmium, copper, chromium, and lead) in tissues and shells of juveniles (13±2.2 mm), medium-size organisms with mature gonads (25±4.1mm), and adults (35±1.2 mm) of the clam Tivela mactroides from three different locations along the Venezuelan coast: Playa Güiria, on the northeastern coast, was not affected by environmental pollution, but Río Chico and Boca de Paparo, influenced by the Tuy River on the central coast, were. Heavy metal concentrations were related to shell size, with significant differences among populations and shell sizes. Specimens from Boca de Paparo and Río Chico had the highest heavy metal concentrations in tissues and shells, in contrast with the levels found in specimens from Playa Güiria, in which chromium and lead were absent. The high heavy metal concentrations found in tissues from specimens collected at Boca de Paparo and Río Chico were possibly of anthropogenic origin and generated by the Tuy River. The environmental conditions at Boca de Paparo may have favored the bioaccumulation of most heavy metals in specimen tissues. At Playa Güiria, however, the heavy metal concentrations were found to be within a natural range. Our results show that T. mactroides is a good biological indicator of the presence of heavy metals in the littoral waters they inhabit.

Valor nutricional do mel e pólen de abelhas sem ferrão da região Amazônica

Avaliou-se os constituintes nutricionais de amostras do mel e pólen das espécies Melipona seminigra merrillae (jandaíra), Melipona compressipes manaosensis (jupará), Melipona rufiventris paraensis (uruçu boca de ralo), provenientes do meliponário da Fazenda Poranga no município de Itacoatiara - AM e Meliponário Abelhudo em Manaus - AM. Os resultados demonstraram o potencial do mel como fonte de energia, particularmente a M. rufiventris com 305,3±2,4 kcal em 100g. O pólen da espécie M. compressipes apresentou a maior concentração de proteína 15,7±0,0% e energia 309,8±0,8 kcal. Tais constatações sugerem a implementação de novos estudos visando à incorporação destes produtos na dieta dos amazônidas, possibilitando uma nova fonte alternativa de alimento potencialmente nutritivo e saudável.

More Mobiliary Art from Northern Mexico:The Pelihal Collection

In 1996, the first evidence of a mobiliary art tradition in northern Mexico was found at Boca de Potrerillos, Nuevo Leon, and reported in Plains Anthropologist. Now, the unsystematic collection of 103 incised stones from Pelillal, Coahuila confirms that at least two technically and iconographically distinct types of mobiliary art were produced by the prehistoric hunters and gatherers of north central Mexico. The simpler stones bear incised linear designs, some of which are comparable to the Lama San Pedro style at Boca de Potrerillos where they were dated to between 230 and 950 B.P At least 18 of the stones bear some portion of a butterfly-vulva form design, sometimes woven into a more elaborate and complex pattern, typical of the Coco nos style. The sexual connotations of the vulva form and the transformational implications of the butterfly theme suggest that these objects were used in puberty or fertility rites, probably during the Archaic period or Coahuila Complex, ca. 5 000 B.P

Distribution and abundance of larvae and adults of Solenocera (Decapoda, Solenoceridae) in the southwestern Gulf of Mexico

The distribution and abundance of larvae of the genus Solenocera and adults of Solenocera vioscai (Burkenroad, 1934) were analysed. Factors affecting their distribution and abundance in Campeche Sound are discussed. We found the occurrence of a period of higher reproductive activity related with the time of maximal primary production during summer, that is, the rainy season when the supply of organic material is greater. A larval dispersion model related to the pattern of predominating water currents in each climatic period is given. During summer, larvae concentrate in front of the Terminos Lagoon, due to the presence of a middle-scale cyclonic gyre. During autumn, larvae are transported to the central region of the study area in front of the Grijalva-Usumacinta system and the Boca de Puerto Real at the outer shelf. Finally, in spring, an anticyclonic current is observed (in southwestern direction), which transports the larvae and tends to concentrate them in front of the coast of Tabasco.

Estado actual de las enfermedades y otros signos de deterioro coralino en siete arrecifes del Parque Nacional Archipiélago de Los Roques, Venezuela

This work was aimed to determine the incidence of coral diseases in six different reef sites at the Parque Nacional Archipielago de Los Roques, Venezuela: Arrecife de herradura, Arrecife costanero, both at Dos Mosquises Sur Key, Boca de Cote, Carenero, Crasqui and Pelona de Rabusqui. Each reef was surveyed by using ten 10 m2 - band transects (10 x 1 m), placed parallel to the long axis of the reef within a depth gradient ranging from 1 to 9 m depth. All healthy and injured corals, along each band transect, were counted and identified to species level. Additionally, all diseases and recent mortality that were still identifiable on each colony were also recorded. The occurrence of diseased colonies and other signs of reef decline between localities were compared by means of a Chi2 test. The absolute, relative and mean incidence was estimated for each disease and other signs of damage observed for all coral species surveyed at each site. The overall incidence of coral diseases was low for all the localities surveyed, only 6.04 % of the 3 344 colonies observed, showed signs of diseases. The most important diseases recorded were the Yellow-Blotch Disease (YBD) and Dark Spots Disease (DSD) with 2.1% ± 1.52 y 2.1% ± 2.54, respectively. Significant differences were found in the incidence of coral diseases between reef sites (Chi2 p < 0.05). Finally, the occurrence of colonies injured by parrotfish bites and pomacentrids was higher compared with the incidence of coral diseases for all the reefs surveyed. In conclusion, currently the proportion of healthy colonies at Los Roques coral reefs is higher than the percentage of both diseased and injured colonies.

Regional controls on geomorphology, hydrology, and ecosystem integrity in the Orinoco Delta, Venezuela

Interacting river discharge, tidal oscillation, and tropical rainfall across the 22,000 km 2 Orinoco delta plain support diverse fresh and brackish water ecosystems. To develop environmental baseline information for this largely unpopulated region, we evaluate major coastal plain, shallow marine, and river systems of northeastern South America, which serves to identify principal sources and controls of water and sediment flow into, through, and out of the Orinoco Delta. The regional analysis includes a summary of the geology, hydrodynamics, sediment dynamics, and geomorphic characteristics of the Orinoco drainage basin, river, and delta system. Because the Amazon River is a major source of sediment deposited along the Orinoco coast, we summarize Amazon water and sediment input to the northeastern South American littoral zone. We investigate sediment dynamics and geomorphology of the Guiana coast, where marine processes and Holocene history are similar to the Orinoco coast. Major factors controlling Orinoco Delta water and sediment dynamics include the pronounced annual flood discharge; the uneven distribution of water and sediment discharge across the delta plain; discharge of large volumes of water with low sediment concentrations through the Rı́o Grande and Araguao distributaries; water and sediment dynamics associated with the Guayana littoral current along the northeastern South American coast; inflow of large volumes of Amazon sediment to the Orinoco coast; development of a fresh water plume seaward of Boca Grande; disruption of the Guayana Current by Trinidad, Boca de Serpientes, and Gulf of Paria; and the constriction at Boca de Serpientes.

Evolution of the Cañadas edifice and its implications for the origin of the Cañadas Caldera (Tenerife, Canary Islands)

The volcano-stratigraphic and geochronologic data presented in this work show that the Tenerife central zone has been occupied during the last 3 Ma by shield or central composite volcanoes which reached more than 3000 m in height. The last volcanic system, the presently active Teide-Pico Viejo Complex began to form approximately 150 ka ago. The first Cañadas Edifice (CE) volcanic activity took place between about 3.5 Ma and 2.7 Ma. The CE-I is formed mainly by basalts, trachybasalts and trachytes. The remains of this phase outcrop in the Cañadas Wall (CW) sectors of La Angostura (3.5–3.0 Ma and 3.0–2.7 Ma), Boca de Tauce (3.0 Ma), and in the bottom of some external radial ravines (3.5 Ma). The position of its main emission center was located in the central part of the CC. The volcano could have reached 3000 m in height. This edifice underwent a partial destruction by failure and flank collapse, forming debris-avalanches during the 2.6–2.3 Ma period. The debris-avalanche deposits can be seen in the most distal zones in the N flank of the CE-I (Tigaiga Breccia). A new volcanic phase, whose deposits overlie the remains of CE-I and the former debris-avalanche deposits, constituted a new volcanic edifice, the CE-II. The dyke directions analysis and the morphological reconstruction suggest that the CE-II center was situated somewhat westward of the CE-I, reaching some 3200 m in height. The CE-II formations are well exposed on the CW, especially at the El Cedro (2.3–2.00 Ma) sector. They are also frequent in the S flank of the edifice (2.25–1.89 Ma) in Tejina (2.5–1.87 Ma) as well as in the Tigaiga massif to the N (2.23 Ma). During the last periods of activity of CE-II, important explosive eruptions took place forming ignimbrites, pyroclastic flows, and fall deposits of trachytic composition. Their ages vary between 1.5 and 1.6 Ma (Adeje ignimbrites, to the W). In the CW, the Upper Ucanca phonolitic Unit (1.4 Ma) could be the last main episode of the CE-II. Afterwards, the Cañadas III phase began. It is well represented in the CW sectors of Tigaiga (1.1 Ma–0.27 Ma), Las Pilas (1.03 Ma–0.78 Ma), Diego Hernández (0.54 Ma–0.17 Ma) and Guajara (1.1 Ma–0.7 Ma). The materials of this edifice are also found in the SE flank. These materials are trachybasaltic lava-flows and abundant phonolitic lava and pyroclastic flows (0.6 Ma–0.5 Ma) associated with abundant plinian falls. The CE-III was essentially built between 0.9 and 0.2 Ma, a period when the volcanic activity was also intense in the `Dorsal Edifice' situated in the easterly wing of Tenerife. The so called `valleys' of La Orotava and Güimar, transversals to the ridge axis, also formed during this period. In the central part of Tenerife, the CE-III completed its evolution with an explosive deposit resting on the top of the CE, for which ages from 0.173 to 0.13 Ma have been obtained. The CC age must be younger due to the fact that the present caldera scarp cuts these deposits. On the controversial origin of the CC (central vertical collapse vs. repeated flank failure and lateral collapse of mature volcanic edifices), the data discussed in this paper favor the second hypothesis. Clearly several debris-avalanche type events exist in the history of the volcano but most of the deposits are now under the sea. The caldera wall should represent the proximal scarps of the large slides whose intermediate scarps are covered by the more recent Teide-Pico Viejo volcanoes.

Continuities in Architectural Traditions: The Subterráneos of Prehistoric and Modern Northern Mexico

The recent discovery of a pit house village, 40 km northwest of Monterrey, challenges the conventional view of inland northeastern Mexico as the domain of purely nomadic hunters and gatherers throughout prehistory. Las Casitas consists of fifty-three subterranean rooms and forty-eight smaller depressions aligned in three slightly arcuate tiers in a small valley adjacent to Boca de Potrerillos, an extremely large open campsite and petroglyph complex that is now an archeological park. Other features of the site are some 325 hearths that surround the depressions and a very limited artifact assemblage numbering only thirty-seven items. Two hearths produced radiocarbon samples that date site occupancy to approximately a.d. 1450, just prior to the arrival of the Spanish in the New World. Las Casitas provides the first evidence of semi-sedentary, surplus producing populations in central northeastern Mexico.

Paleoseismicity studies on the Oca-Ancón fault system, northwestern Venezuela

The E-W-trending, right-lateral Oca-Ancón fault system extends eastward for 650 km, from the Colombian Caribbean coast near the city of Santa Marta to the town of Boca de Aroa (located on the eastern coast of Falcón State, northwestern Venezuela), across the Goajira peninsula, the outlet of Lake Maracaibo, the coastal plains of Buchivacoa and the central Falcón range. This system is very conspicuous west of the city of Maracaibo where its single trace sharply truncates the northern ends of the Santa Marta block and the Perijá range. Fault-related landforms along the system trace (e.g., displaced beach strandlines at Sinamaica and fault scarplets in the Buchivacoa plains) suggest that it may have been active during Holocene times. A first trenching attempt carried out north of Maracaibo (at Sinamaica) in 1969 only confirmed its Holocene tectonic activity. On the western coastal plains of Falcón State and east of Lake Maracaibo, the system is less simple as it is composed of two parallel fault strands but they are clearly evidenced by Holocene paleoseismic scarplets. Recently, this system has been paleoseismically evaluated by means of two trenches placed across each of the two parallel branches known as the Oca and the Ancón faults. Dimensions of these bulldozer-dug trenches are 80 m long and 8 m deep. Various lines of evidence obtained from these exploratory trenches indicate that: (a) three surface rupture events, dated slightly prior to 7755 ± 320, 6240 ± 39 and 1945 ± 630 yr B.P., have occurred along the Oca fault; (b) one surface rupture event has occurred within the past 3125 ± 185 yr on the Ancón fault; (c) the Holocene slip rate of the system is close to 2 mm/yr; and (d) either of the faults can generate a maximum event of magnitude 7.4–7.5 Recurrence of such earthquakes on the Ancón fault is close to 1900 years while it is about 4300 years on the Oca fault.

The Mobiliary Art Of Boca De Potrerillos Nuevo LeÓN, Mexico

Two types of incised tabular sandstone rocks were recovered from two spatially and temporally distinct areas within the large petroglyph/open camp site of Boca de Potrerillos in the northeastern Me...

Reproduction and Breeding Success of California Least Terns in Jalisco, Mexico

The Least Tern (Sterna antillarum) is broadly distributed in the United States, with three well-defined subspecies: browni is found along the west coast, athalassos in the central U.S., and antillarum along the east coast and the West Indies (Massey 1981). The status of two subspecies described from Mexico, mexicanus from Sonora (Van Rossem and Hachisuka 1937) and staebleri from Chiapas (Brodkorb 1940) is uncertain. Least Terns have disjunct summer and wintering ranges, breeding in northeast, central, and southwest United States south to Baja California and Sonora in Mexico, and on some Caribbean islands. The east coast population (S. a. antillarum) comprises more than 75% of all the individuals (Buckley and Buckley 1984; Clapp and Buckley 1984). The California Least Tern (S. a. browni) is less abundant; the largest concentration recently recorded is in San Diego, California (Massey 1981). It is considered endangered; its populations began to decline early this century, mainly because of habitat loss, disturbance of nesting sites, and predation by domestic and wild mammals (King 1981, Massey 1981, Jehl 1984, Vermeer and Ranking 1984). California Least Terns breed from the San Francisco Bay in California southward to the tip of the Baja California Peninsula and Sonora, Mexico (Russell and Lamm 1978, Massey 1981, Mellink and Palacios 1993); early in the century a breeding colony was recorded in Oaxaca (Binford 1989). It winters along the coasts of western Mexico, south to northern South America (King 1981, AOU 1983). A group of seventy-five wintering Least Terns was found in Colima in 1979; additionally, some banded Least Terns were found in the same area in 1981, and this region is considered the northern limit of its wintering range (Massey 1981). We report here the first recent tropical breeding record of Least Tern in Mexico, from the Cuixmala River in Jalisco, 150 km to the north of Boca de Pascuales, Colima, the northern limit of the wintering range (Massey 1981). Aside from extending the recent breeding records in Mexico more than 1,000 km to the south, we report the only clutch size data for this subspecies from the tropics, and raise questions about its summer and wintering distribution range. STUDY AREA

The Archaic Environment of Boca De Potrerillos, Nuevo León, Mexico

Nine new radiocarbon dates expand the occupational sequence at Boca de Potrerillos, a large open camp site on the fringes of the Sierra Madre Oriental in Nuevo León, Mexico, to the range between 270 and 7700 years ago. Incised stones attributable to the Archaic component provide an estimate of the age of some of the 3000 petroglyphs at this site. Cut-and-fill cycles, pollen counts, and gastropod analyses contribute to the definition of two climatic episodes. Between 980 and 1280 years ago, low energy sedimentation suggests a benign climatic interlude prevailed locally. Massive erosion at Boca de Potrerillos and other excavated sites within a 150 km range identifies a period of regional environmental stress around 4800 years ago.

From Marshland to Desert: The Late Prehistoric Environment of Boca de Potrerillos, Nuevo León, Mexico

Despite the paucity of archaeological research in the Sierra Madre Oriental ecotone of northeastern Mexico, a patterned distribution of large open campsites replete with petroglyphs is suggested by a recent rock art survey sponsored by the Mexican government. Pilot research at Boca de Potrerillos, one of the largest and best preserved examples of this site type, demonstrates that the intermontane desert of today was once a combination of grassland and wetland. Hundreds of hearths are now exposed on the surface of a desiccated alluvial plain and thousands of petroglyphs have been incised into sandstone boulders fringing the occupational area. Radiocarbon assay of charcoal derived from buried hearths dates the intact subsurface living surfaces to the period between 1350 and 650 years ago. Pollen and phytolith samples from buried strata and ground stone implements describe a mesic environment and provide a list of potential economic plants processed at the site. The presence of both aquatic and terrestrial snails supports the paleoenvironmental reconstruction of wetlands, replete with emergent vegetation, flanked by rocky slopes. Archival research suggests that a drying trend is mirrored in the agricultural history of the valley but the extreme degradation effected in the last four decades is attributable to modern exploitation of the aquifer.