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Alcalá de Henares, Spain

Ashley G.M.,Rutgers University | Bunn H.T.,University of Wisconsin - Madison | Delaney J.S.,Rutgers University | Barboni D.,Aix - Marseille University | And 6 more authors.
Quaternary International | Year: 2014

The multi component FLK North archaeological site was discovered over 50 years ago, and its interpretation has been highly controversial since. Explanations of the dense bone and stone tool accumulation range from a site on a featureless lake margin that is dominantly anthropogenic in origin to a site near a freshwater wetland that is dominated by carnivore activity (e.g. felids and hyenas). FLK North occurs stratigraphically between the Ng'eju Tuff (1.818 ± 0.006 Ma) and Tuff IF (1.803 ± 0.002 Ma), and is composed of 9 distinct levels. Analysis of newly recovered fossil bones and artifacts has shown that the bones of large animals are largely the product of felid hunting and feeding behavior, followed by hyena gnawing and breakage of some bones. The expanded sample of felid prey remains is significant for understanding the contrasts between the mortality profiles of fossil assemblages produced by carnivores and those produced by hominins. Geologic mapping in the environs of the site has revealed rich sedimentological and paleoecological records and a thin, but persistent tuff (here named Kidogo Tuff) that is ~1.5 m below Tuff IF. Electron microprobe analyses of the tuff mineralogy revealed a unique geochemical fingerprint that permits its use for correlation of widely separated outcrops and facilitates the high resolution reconstruction of the landscape at the time of site formation. The 9 archaeological levels comprise a relatively continuous record through a Milankovitch precession cycle (dry-wet-dry). As the lake receded into the central basin during the dry part of the cycle, surface water supplies dwindled and groundwater-fed springs and wetlands became the dominant freshwater supply. The FLK North archaeological record essentially ended when level 1 was covered with 0.4 m of Tuff IF in a violent volcanic eruption of nearby Mt. Olmoti. However, the overlying Bed II sediments contain scattered archaeological material and a freshwater carbonate deposit that is similar to those found associated with other Bed II archaeological sites, e.g. VEK, HWK and HWKE. The recognition of the ecological association of springs, wetlands and archaeological remains is a powerful predictive tool for locating new archaeological sites in this region that is known for hominin remains. © 2013 Elsevier Ltd and INQUA. Source


Ashley G.M.,Rutgers University | Dominguez-Rodrigo M.,Complutense University of Madrid | Bunn H.T.,University of Wisconsin - Madison | Mabulla A.Z.P.,University of Dar es Salaam | Baquedano E.,Museo Arqueologico Regional de Madrid
Journal of Sedimentary Research | Year: 2010

Recent field work at Olduvai Gorge (Tanzania) using sedimentary geology, in particular high-resolution paleoenvironmental reconstruction and isotope geochemistry, has revealed that freshwater was in proximity to a number of the rich fossil sites in Beds I and II (̃ 2.0-1.0 Ma). This paper presents the fìrst geological evidence for springs associated with archaeological sites in this semiarid rift basin. The springs appear to be limited to a small area within the basin and were likely connected to faults that acted as conduits for groundwater. Tufas associated with ten archaeological sites have stable-isotope signatures occurring in a cluster bounded by δ 180 ratios from -6% to +1%, and the δ 13C ratios from -5% to +2%. The δ 180 values cluster around -4%, that of precipitation in the region, indicating a meteoric source. The longevity of the spring record reflects a hydrologic system that apparently persisted for hundreds of thousands of years. Previous landscape reconstructions depicted the archaeological sites on the lake margin of paleo Lake Olduvai, as an alkaline playa. The discovery of springs at or near the archaeological sites provides fresh insights for interpreting hominin behavior during this key time in evolution with respect to procuring food, water, and materials for stone tools, as well as hominin adaptation to climate change and paleoenvironmental change. The idea that spring deposits may be in proximity to archaeological sites could lead to discovery of new sites at other hominin fossil localities in the East African Rift System (EARS). Copyright © 2010, SEPM (Society for Sedimentary Geology). Source


Laplana C.,Museo Arqueologico Regional de Madrid | Blain H.-A.,Institute Catala Of Paleoecologia Humana I Evolucio Social | Blain H.-A.,Rovira i Virgili University | Sevilla P.,Complutense University of Madrid | And 3 more authors.
Quaternaire | Year: 2013

The High Valley of the Lozoya in Central Spain is presently one of the most diversified environments for small terrestrial vertebrates in the Iberian Peninsula, with 13 species of amphibians, 17 reptiles and 26 small mammals. Karstification of the Cretaceous limestones that crop out on either slopes of the Lozoya Valley has given place to the formation of caves, many of which preserve Upper Pleistocene and Holocene sediments with abundant fossils and human remains, currently under study. The first of these fossil localities to be discovered was the Cueva del Camino, presently a dismantled cave that preserves sediments dated between 91.6 ± 8.1 ka and 74.5 ± 6.3 ka, containing evidence of having been used as a den by hyenas. Besides large mammal fossils, probably introduced in the cave by hyenas, at least 49 species of small vertebrates (7 amphibians, 11 reptiles and 31 small mammals) are represented in this assemblage, indicating that at that time, the Lozoya Valley had a highly diversified community of small vertebrates, equally rich or even richer than today. The conditions favouring this high species richness are analysed. Source


Ashley G.M.,Rutgers University | Barboni D.,Aix - Marseille University | Dominguez-Rodrigo M.,Complutense University of Madrid | Dominguez-Rodrigo M.,IDEA Institute Evolucion en africa | And 6 more authors.
Quaternary Research | Year: 2010

The records of early hominins are commonly localized both temporally and spatially even in archaeologically rich basins like Olduvai Gorge, Tanzania. The FLK North site was discovered in 1960, but the reason for the exact location of this dense concentration of fossils and stone tools on a lake-margin flat has not been explained. We present new geological and geochemical information from six excavations in upper Bed I, which revealed up to 1.4-m-thick carbonate deposits, attesting to the presence of freshwater springs in the area surrounding FLK North. The δ18O signatures of the tufa are typical for meteoric water that has evolved during evaporation. Tuff IF that caps the sequence was deposited on uneven topography with the highest area a low-relief ridge between two faults at the archaeological site and lowest areas being sites of groundwater discharge. The model proposed here is that rainfall on adjacent highlands was transported to the basin where faults acted as conduits for water. Similar hydrogeological settings at modern lakes Manyara and Eyasi, currently support lush groundwater forest and woodland despite arid climate. FLK North may have been an "oasis" offering freshwater and shelter for consuming meat by both carnivores and hominins. © 2010 University of Washington. Source


Blain H.-A.,Institute Catala Of Paleoecologia Humana I Evolucio Social | Blain H.-A.,Rovira i Virgili University | Laplana C.,Museo Arqueologico Regional de Madrid | Sevilla P.,Complutense University of Madrid | And 3 more authors.
Boreas | Year: 2014

The Cueva del Camino site (Pinilla del Valle, Madrid, Spain) is located in the upper valley of the Lozoya River in the Sierra de Guadarrama, a mountain range extending NE-SW within the Central Range System. Due to its location within a mountain range on the central Iberian Peninsula at an altitude of 1114ma.s.l. and the numerical dating of its sediments, the palaeontological site of Cueva del Camino has proved a highly relevant location for studying the ecological changes linked to the climatic fluctuations at the end of Marine Isotope Stage (MIS) 5 and the beginning of MIS 4. Environmental reconstructions suggest a rather open, patchy landscape throughout the succession, with abundant evidence of dry meadows, scrublands and rocky habitats. The climate can be considered as generally warm, reaching mean annual temperatures (MATs) of up to 13.8°C (i.e. higher than today's by up to 2.9°C). Three cooler events can be seen throughout the succession as reflected by the presence of Rana iberica, Anguis fragilis and Coronella austriaca. The first of these events may correlate with MIS 5b; the second in the Central sector may correlate with the Stadial I pollen event occurring at the end of MIS 5a; and the third event, corresponding to the coldest MAT of the entire succession with MATs 0.9°C lower than today's, may correspond to the transition from MIS 5a to MIS 4. The evolution of mean annual precipitation (MAP) is characterized by warm periods, drier and cold periods, as well as wetter periods (up to +356mm compared to today's MAP values), similar to what occurs today in the high-elevation areas of the neighbouring mountains. Our study gives new quantitative estimations for the climatic fluctuations in mountain environments of central Spain at the MIS 5/4 transition and their associated ecological changes. © 2013 The Boreas Collegium. Source

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