of chemical weathering and preservation of easily weather- able pyroxenes and amphiboles might have been the result of either a very cool or arid climate or some combination of both. Similarly, the lower to intermediate chemical weather- ing during deposition of rest of the sediments suggest rela- tively humid and varying climatic conditions at the source terrains. This is also supported by the presence of smectite and kaolinite in some of the sediments and their absence in others (Figures 5c). On the other hand, lower chemical weathering can also be the result of a tectonically active hinterland (upliftment of igneous rocks) causing its erosion at a higher rate (Andersson et al., 2004). The short time span of exposure to weathering (possibly enhanced by erosion or burial of younger sediments) might have led to lower alteration of the deposited sediments at Pachuca sub-basin. In addition, there are various glacial and interglacial periods registered in high resolution late Quaternary paleoclimatic registers during the time span that cover the studied stratig- raphy (last 1.50 Ma). However, it is difficult to propose a paleo-climatic reconstruction in the absence of any precise chronological constraint of the studied profile .
15 Lee mas
The abundance and distribution of ostracodes in the upper 865 cm of a sediment core recovered from Babícora paleolake allows reconstruction of paleoecological conditions in the western Chihuahuan Desert by inferring variations in temperature and salinity of the lake water over the last ca. 72 cal kyr BP. The ostracode assemblage consists of five species (Candona patzcuaro Tressler, Cypridopsis vidua Brady, Limnocythere bradburyi Forester, L. platyforma Delorme and L. Ceriotuberosa Delorme), and its abundance varies between 0 and 1441 valves/g. Low ostracode abundance suggests the presence of dilute lake water (salinity>100 ppm) with abundant fresh water inflow into the basin prior to ca. 57 cal kyr BP. During ca. 57-49 cal kyr BP salinity remained low (>100 ppm), but the water column was characterized by cold temperatures (>4 °C). Sediments of this zone have higher organic carbon content. Conditions were optimal for ostracode productivity (abundance of 44-1441 valves/g) during ca. 49-29 cal kyr BP, and this zone indicates fluctuating temperature (5-32 °C) and salinity (100-100,000 ppm). A warm water column (>13 °C) and salinity of >500 ppm are inferred during ca. 29-12 cal kyr BP. Sediments of the last 12 cal kyr BP lack preserved ostracodes, and precipitation of authigenic calcite indicates periodic desiccation of the lacustrine basin during the Holocene. The inferred paleoecological conditions in the western Chihuahuan Desert are synchronous with other proxy-based late Quaternary paleohydrological and paleoclimatic information obtained from southwestern USA and northern Mexico.
10 Lee mas
The Pampa del Tamarugal (PDT) is a major geographical feature in the northern Atacama Desert (19 17 0 -21 50 0 S, 1000 m a.s.l.) (Fig. 2a). The PDT is a semi-enclosed basin, and is hydrologically recharged from precipitation from the Andes to the east. Salars in the PDT are fed by groundwater, and several drain southward into the Loa river (Salar de Pintados, S. de Bellavista, S. Viejo and S. de Llamara) (Fig. 2a). The PDT lies atop a thick sedimentary sequence deposited unconformably over eroded bedrock basement of metamorphic (e.g. phyllite) and sedimentary (e.g. sandstone, limestone) origin (S aez et al., 1999). Sediment began accumulating in the Oligocene, and has continued into the present, although sedimentation rates decreased drastically c. 11 Myr ago and have remained low ever since, especially in the southern portion of the basin (Nester and Jordan, 2012). The long-term sedimentary sequence is derived from two distinct sources: (1) alluvium and volcanics descending west toward the basin axis from the Andean plateau, and (2) riverine, lacustrine, and evaporite deposits from the Loa river and other major streams along the southern basin axis. Although there is ample evidence for saline lakes or wetlands in pre-Quaternary sediments, there have been no reports of wetland or lacustrine conditions in any of the basins of this region during the late Quaternary (S aez et al., 1999; Kirk-Lawlor et al., 2013). Instead, halite and sulfate capped landscapes are the most striking features of the lowest elevations at present (Stoertz and Ericksen, 1974).
22 Lee mas
The hyperarid core of the Atacama Desert possesses important reserves of “fossil” or ancient groundwater, yet the extent and timing of past hydrologic change during the late Quaternary is largely unknown. In situ and/or short-distance transported leaf-litter deposits abound along relict ﬂuvial terraces inserted within four dry and unvegetated valleys that drain into the endorheic basin of Pampa del Tamarugal (PDT, 21°S, 900 – 1000 m), one of the largest and economically important aquifers in northern Chile. Our exceptional ar- chive offers the opportunity to evaluate the response of low-elevation desert ecological and hydrological sys- tems to late Quaternary climate variability. Three repeated expansions of riparian/wetland ecosystems, and perennial rivers occurred along the southernmost PDT basin between 17.6 – 14.2 ka, 12.1 – 11.4 ka and from 1.01–0.71 ka. Both early and late archaic archaeological artefact are present in clear association with our fossil riparian/wetland assemblages, which suggests that these palaeoenvironmental changes facilitated past human occupations in the hyperarid core of the Atacama Desert. Using modern analogues, we estimate that these ecological and hydrological changes were triggered by a threefold increase in rainfall along the headwaters of what are presently inactive canyons. Comparisons with other regional palaeoclimatic records from the central Andes indicate that these changes were synchronous with the widespread pluvial stages now termed the Central Andean Pluvial Event (CAPE— 17.5–14.2 ka and 13.8–9.7 ka). In addition, we sum- marize new evidence for perennial runoff, riparian ecosystems and a major human settlement during the latest Holocene. Our ﬁ ndings clearly show that local hydrological changes in the PDT were coupled with precipitation variability in the adjacent eastern highlands during the late Quaternary. The long-term dynamics of low- elevation desert ecological and hydrological systems are likely driven by changes in moisture sources, with one source tied to the Amazon region (N – NE mode) and the other to the Gran Chaco region (SE mode). We con- clude by linking ENSO-like variability and moisture variations over the Gran Chaco to the three major regional- scale recharge events over the last 18 ka in the PDT basin. We conclude by asserting that an important portion of the groundwater resources in the PDT is indeed fossil, inherited from past pluvial events. We recommend that the relationship between ancient recharge, together with palaeoclimate records of past headwater rainfall ﬂuc- tuations should be incorporated into future water-balance models and evaluation of groundwater potential in northern Chile.
21 Lee mas
Rising above the abrasion terraces is a steep (10°) abrasion moraine step to the middle Pleistocene terraced surface composed of the main Moscowian moraine (140– 170 m a.s.l.), which occupies a large part of the study area (Figure 2). The surface of this level is characterized by flat plains topography with inclusion of individual hills with a relative height of up to 10–15 m. The topography of these hills is gentle, the tops of the hills are flat, and slopes are less than 5°. Soil forming materials that occur in this territory belong to different kinds of Quaternary deposits. Noncalcareous loess-like loams are restricted to the areas closest to the abrasion step and to flat areas between the hills. The noncalcareous loess-like loams are underlain by moraine loams at a depth of 1.0 m and are less widespread. These parent materials alternate with sporadic outcrops of layered glaciolacustrine sands. The elevated levels of topography within this surface (up to 170 m a.s.l.) are covered by moraine loams.
7 Lee mas
To further our understanding of plant biogeography and its relationships with past climate change in the Atacama Desert, we present a new rodent midden record that spans more than 40,000 years. These samples were collected at Quebrada La Higuera (QLH) in the precordillera of the wes- tern Andes (Fig. 1) along two elevational bands. Rodent middens have been previously reported here (Holmgren et al., 2001b, 2008), but the QLH midden record is the only record from this region with late Pleistocene middens, and is key for understanding how plant species responded to the end of the last glacial cycle. We use midden pollen, plant macrofossil evidence and chinchilla rat (Abrocoma cinerea) pellet diameters (a proxy for body size; see Smith et al., 1995; Latorre et al., 2010) to infer past environmental and vegetation change.
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3) Ambiguity of lacustrine records: some elements of the lacustrine records in central Mexico are not uniformly interpreted. For example, earlier studies of lake cores within the TMVB reported a lower ratio of arboreal to non-arbo- real (AP/NAP) pollen as an important argument in favor of “drier” LGM (e.g., Ortega-Guerrero et al., 2000). However in a recent paper about the vegetation history of the Upper Lerma basin, although referring to LGM in central Mexico as being relatively dry, Lozano-García et al. (2005) state that “altitudinal fluctuation of the plant communities during the local glacial advances could explain the high percentages of grass pollen”. They acknowledge that the increase of grass pollen in late Pleistocene strata could be due to the lower- ing of the tree line to about 3000 m.a.s.l. (currently close to 4000 m.a.s.l.) and the expansion of alpine meadows, thus presenting a temperature rather than humidity signal.
18 Lee mas
Paleosol sequences of the Nevado de Toluca volcano (NTV) preserve a detailed record of late Quaternary environmental change. In fact, some studies have been used the NTV paleosols to interpret paleoenvironmental conditions, however some uncertainties still remain concerning their stratigraphic position and correlation. In this paper, we present the results of the NTV pedostratigraphy by using different paleosol units and based on present day tephrostratigraphy. We recognized eight Pleistocene paleosols, labeled PT0–PT7 which cover the 100,000–10,000 yr BP interval. These paleosols are located in four exposures: Arroyo La Ciervita, in the northern flank of the volcano, Zacango, in the northeast, and San Pedro Tlanisco and Barranca Cieneguilla, in the eastern part. The younger five paleosols correspond to different intergrades of Andosols (PT0–PT4) while the older sequence consists of three well developed Luvisols (PT5–PT7). All Andosols have humic horizons allowing radiocarbon dating. PT0 and PT1 were formed at the end of the Pleistocene and correlate with the oxygen isotope stage (OIS) 1 and to the middle-late OIS-2, respectively; the time for PT2 formation corresponds to the end of OIS- 3 and the beginning of OIS-2, PT3 to the OIS-3, and PT4 to the OIS-4. PT5–PT7 have not yet been dated, but we correlate them with the OIS-5a and 5b. A more strongly developed paleosol (PT1) was formed during the Last Glacial Maximum (18,000 yr BP) in comparison with other paleosol sequences where weakly developed paleosols were reported or even no soil formation was achieved in this period. We conclude that during late Pleistocene to Holocene, OIS 5 to 1, paleosol sequences of the Nevado de Toluca provide good environmental resolution, similar to or even higher than loess-paleosol sequences, although stratigraphic correlation with other paleoenvironmental records is more difficult because of the heterogeneity of volcanic sediments.
9 Lee mas
The presence of titanosaurids in northern Mexico is not surprising if dispersal did indeed occur from South America toward North America. Unfortunately, the geology of this part of the country is poorly known, there is only one unpublished geological study of the area made by F. Palomino and M. Vega, staff members of the INEGI (Instituto Nacional de Estadística, Geografía e Informática). The spotty outcrops of these formations are small. Their report suggests that it is not possible to distinguish the continental Aguja Formation from the lower part of the Javelina Formation. The age of these formations is considered to range from late Campanian– late Maastrichtian (Lehman, 1985). Titanosaurids have been collected in the Maastrichtian beds of the Big Bend National Park (Lawson, 1972). Lehman and Coulson (2002) reported Alamosaurus sanjuanensis from Black Peaks Formation, also in the Big Bend National Park, just below the Cretaceous–Tertiary boundary horizon. The presence of this dinosaur in Chihuahua represents the first record of a titanosaurid in Mexico.
5 Lee mas
Fossil remains of Mesozoic crocodyliforms are scarce in Mexico. Some material assigned to Thalattosuchia has been recently described for the marine Late Jurassic of Puebla (Geosaurus vignaudi Frey et al., 2002), Nuevo León (Velasco-Segura, 2007) and Coahuila (Geosaurus saltillense Buchy et al., 2006). A few Cretaceous crocodyliforms have been discovered in northern Coahuila. Two fragmentary skulls of dyrosaurids have been shown to two of us (EF and WS) by private collectors at Sabinas, and material referable to dyrosaurid crocodilians was collected at Las Aguilas but not yet been published. Recently, fragments of the giant alligatoroid Deinosuchus have been described from the Late Cretaceous (Campanian) San Carlos Formation in northern Chihuahua, south of Ojinaga (Westgate et al., 2006; Brown et al., 2004). Rivera-Sylva et al. (2009b) mentioned a tooth referred to cf. Deinosuchus from a new fossil site located near the border region between the Mexican states of Chihuahua and Coahuila (Figure 1). Further evidence for Deinosuchus came from the Aguja Formation (Late Cretaceous, late Campanian) near the town of La Salada in northwestern Coahuila, Mexico (Rivera-Sylva et al., 2008; Figure 1). These discoveries expanded the occurrence of Deinosuchus some 60 km further to the south than was previously known. However, the material was undiagnos- tic to species level. The material described in this paper represents the fi rst record of skeletal elements diagnostic for Deinosuchus riograndensis (Eusuchia, Alligatoroidea). All fragments presented here likely come from the same individual with the exception of one vertebra. The speci-
8 Lee mas
Stratigraphic distribution. Rancholabrean, late Pleistocene. Diagnosis. One of the smallest North American horse species for late Pleistocene, larger than Equus tau Owen. Although no complete skulls or mandibles, several upper and lower teeth rows (P2/p2-M3/m3), very small in size and some of the mandible rami are almost complete like the holotype. Upper and lower cheek teeth are morphologically very similar to the other horses found at Cedral, but smaller in size. The upper teeth have a protocone elongate more distal than mesially and with a small lingual groove; with styles, parastyle, and mesostyle on premolars wide with a groove and narrow without grooves on molars. The lower teeth have metaconid-metastylid (double knot), rounded or slightly angular, respectively. The ectoflexid is superficial in premolars and molars without crossing the isthmus, only on molars with an advanced wear the ectoflexid are deeper, crosses the isthmus, and could touch the linguaflexid; the linguaflexid is large and more or less U shape. The symphysis has a linear arcade with large canines (a possible male). The body mass is between 91.83 and 169.59 kg, and the mean is 138.41 kg following Alberdi et al. (1995) on the MCIII13. The appendicular skeleton is also small in size with metapodials not stilt- legged, clearly different from the other remains from Cedral and other Mexican localities. In fact, the Mexican new species has metapodials shorter and less slender than both francisci and alaskae.
17 Lee mas
In this work, the clay mineral composition is related to some soil-forming processes and characteristics, i.e., soil ageing, eluviation and illuviation, fragipan and bleached tongue formation, and origin of discontinuities within a soil profile. These processes are of particular interest, because they characterize paleosols formed in the Quaternary in many places, not only in the Mediterranean environment. The clay mineral composition of a soil, as well as the variations between its horizons and the parts of the same horizon, mark the mineralogical transformations due to soil-forming processes. They are the ‘genetic signals’ of pedogenic events (Bockheim and Gennadiyev, 2000). Such genetic signals found in the Montagnola Senese soils can be used to correlate and understand soil-forming processes that occurred in other territories in the Quaternary.
16 Lee mas
Como estrategia de posicionamiento para cualquier marca País o región está enfatizada en el marketing, donde se aplica la creación de ofertas de productos tangibles e intangibles, donde lo que se busca es aumentar la competitividad del departamento y atraer la inversión tanta nacional como extranjera. Nuestro esfuerzo como marca región Choco ‘’late en vos’’ es articular varias organizaciones para lograr captar y obtener clientes potenciales en un lapso de tiempo indefinido, esto se logra con la visibilización de la cultura, la gastronomía, la gente, cosas esenciales que nos hacen únicos como departamento.
40 Lee mas
A lo largo de estos once años trabajando en el H. Ayuntamiento de Colima he tenido la oportunidad de aplicar los conocimientos adquiridos en mi escuela y la oportunidad de seguir aprendiendo sobre diferentes áreas a través de cursos y diferentes capacitaciones, conocí la importancia de reciclar los desechos de la basura, para apoyar al medio ambiente de nuestra madre tierra, esto haciendo una buena administración del programa Reciclar Me Late, me llevo hacer un estudio de la organización del personal de apoyo que contaba el programa, se planeó las rutas y así poder atender las escuelas establecida del día, se recabaron toneladas de material de reciclado, y que se evitó ir al relleno sanitario, a los ciudadanos de la identidad, se les informo haciendo promoción por televisión, ferias nacionales e internacionales, videos, página del H. Ayuntamiento de Colima y los medios de mayor aceptación por el universo Facebook, twitter e internet, también aprendí que como servidor público es de máxima importancia conocer las necesidades de los colimenses para poder orientarlos en los temas de tramitología que requieren.
149 Lee mas
The mid- to late-Campanian Jada´n Formation represents the oldest Cretaceous sediments exposed in the Cuenca area. Although the stratigraphic contact is not visible, we assume it was unconformably deposited onto the metamorphic base- ment of the Andean margin. A similar unconformable con- tact of transgressive, mid- to late-Campanian deposits resting on deformed, Albian to Paleozoic rocks of the Andean margin is known from the forearc zones of south- western Ecuador and northwestern Peru (Jaillard et al., 1996, 1998, 1999; Taipe et al., 2004). Therefore, a strong sub- sidence probably affected the western edge of the Andean continental margin of southern Ecuador by the mid-Camp- anian. Because this subsidence event followed the compres- sional ‘‘Peruvian phase,’’ we suggest that the latter was responsible for a strong tectonic erosion of the forearc con- tinental edge, which accounts for the subsequent subsidence of the forearc zones (Jaillard and Soler, 1996).
12 Lee mas
Sponholz et al. (1993) observed intermittence between palaeoclimatic events in desert lakes and surrounding geomorphology (e.g., the water level of these lakes) when they identified relics of fulgurites (concretions in the Sahara sand produced by lightnings at former lake levels), which enabled them to reconstruct the desert lake level with time. Similarly, Roy and Smykatz-Kloss (2007) studied the REE geochemistry of evaporites and the degree of roundness of rock fragments in the clastic fractions of sediments in order to reconstruct the palaeo-fluvial conditions in the Thar Desert. Fromm et al. (2005) used Fe-Mn vein mineralisations and the different stages of calcrete formation as indicators of the development of the Tunisian desert. Roy et al. (2009, 2010) used geochemical signatures of chemical weathering and mineralogical composition of playa lake sediments to reconstruct late Holocene hydrological changes at the margins of the Thar Desert (India) and late Pleistocene-Holocene palaeo-environmental conditions at Sonora Desert (Mexico).
12 Lee mas
A further point is to ascertain whether technologies such as those represented at Atapuerca-TD6, K€ arlich Ba and Korolevo Complex VII (late Mode 1 from c. 900 ka) or even earlier European assemblages may have evolved into the Acheulean. However, the Acheulean in Europe has a highly problematic de ﬁ nition, given that many northern and eastern sites do not contain large cutting tools. In other works (Mosquera et al., 2013; Oll e et al., 2013), we studied the technical features of all of the lithic assemblages from Sierra de Atapuerca, and we extracted several technical parameters that we consider signi ﬁ cant for characterizing each technology repre- sented, and their possible evolution. These technological features concern the methods of ﬂ ake production, the presence/absence, diversity, standardization and the intense con ﬁ guration of small retouched tools on ﬂ akes; and the presence/absence of large bifa- cial tools (Table 4).
17 Lee mas
«Late», no por la conjugación del verbo latir, sino como apócope de «la tengo». Todos los que hayamos pasado por un patio escolar en edad primaria hemos jugado a las figuritas. Pequeñas siluetas de cartón de formas geométricas con imágenes que representan las más variadas temáticas, personajes de alguna película o de al- gún programa de televisión del momento, o asociadas al mundo del deporte (casi siempre fútbol) con el rostro de los jugadores de cada equipo del campeonato local o del torneo mundial en disputa. Develaría mi edad si dijera que también las hubo de chapa pintada, un latón de forma circular con impresos de automovilismo.
11 Lee mas
Deuteronomio capítulo 26 y el versículo 9 por favor, Deuteronomio Capítulo 26 y el versículo 9. Yo no nací en Pereira, pero soy Pereira ¿no? le, ¿le puedo decir algo? Cuando yo viajo a todas las ciudades predicando me preguntan: ¿de dónde es? a mi; yo, yo nací en la Costa Atlántica, nos criamos en varias ciudades; pero a mi no me conocen en Estados Unidos, ni en Europa, no me conocen como un pastor de “X” ciudad ¿Dónde nací? por ejemplo: la gente dice el pastor de Pereira y seguramente aquí hay algo que cada vez que este corazón late, late por esta ciudad; y el mensaje que hoy le voy a predicar tiene que ver con el gran privilegio que hace parte del ser y estar hoy en esta ciudad; mire, aquí en la tarima hay un grupo grande de personas jóvenes que no, no son de aquí de la ciudad; aquí en la iglesia hay personas que sé que han venido de otras ciudades; pero estar en Pereira, ser parte de Pereira es un gran honor, y proféticamente inicio el mensaje de hoy: “Pereira una tierra de bendición” leyendo con usted Deuteronomio capítulo 26 y versículo 9 y lo vamos a leer con voz potente, y aquí usted va a encontrar una palabra que Dios te da como promesa, ¿está listo?
98 Lee mas
Schweitzer et al. (2012) revised 19 incomplete specimens from four localities of the late Albian Weno and Pawpaw formations near Fort Worth, Texas, and based on these specimens, Schweitzer et al. (2012) included details of the cuticle. Occurrence of the specimen described here as C. americanus from the Grayson Formation, represents an extension of the stratigraphic range of the species, from the upper Albian to the lower Cenomanian in Texas. The specimen (NPL-62056) described here as C. americanus was collected by the second author from the Grayson Formation. A detailed review of the English specimens could reveal if the species had a wide distribution during late Albian/early Cenomanian times.
7 Lee mas