martes, 24 de abril de 2012

Nuevos artículos en TRACCE

TRACCE Noticiario online de arte rupestre, nuevos artículos  (Marzo y Abril 2012).
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Vía RupestreWeb

New evidence argues against prehistoric extraterrestrial impact event

Evidence used to support a possible extraterrestrial impact event is likely the result of natural processes, according to a new collaborative study led by U.S. Geological Survey scientists.

Elevated levels of iridium, magnetic spherules, and titanomagnetite grains, collectively called "impact markers," form the bulk of the evidence for the Younger Dryas impact hypothesis, a hotly contested idea that links climate change, extinctions, and the demise of the Clovis culture.

Scientists found high levels of the reported markers in deposits called black mats, the organic-rich remains of old marshes and swamps, at several sites in the southwestern U.S. and the Atacama Desert of northern Chile. Markers were found in black mats ranging in age from 6,000 to more than 40,000 years in areas far removed from the purported impact location. These findings indicate the markers accumulated naturally in wetlands and are not the result of a catastrophic impact event. The full report is available online.

"Luis and Walter Alvarez's proposal that an extraterrestrial impact was responsible for extinctions at the Cretaceous-Tertiary boundary eventually moved from unlikely hypothesis to accepted theory, and with its acceptance came the temptation to apply this explanation to any rapid change in Earth's conditions," said USGS Director Marcia McNutt. "The results of this study demonstrate the importance of maintaining a healthy skepticism and multiple working hypotheses."

The controversial Younger Dryas impact hypothesis contends that an extraterrestrial object, possibly a comet, exploded over North America about 12,900 years ago, resulting in dramatic climate change, massive wildfires, and the extinction of many large herbivores and their predators. If true, the recency of such a large impact might have implied a greater risk to humanity than previously imagined.

"When the idea was first promoted in 2007, those of us familiar with black mats suspected that normal depositional processes in wetlands might be responsible," said Dr. Jeff Pigati, a USGS geologist and lead investigator of the new study. Indeed, this is what Pigati and coauthors now report in this week's issue of Proceedings of the National Academy of Sciences, USA.

"This is a great object lesson for how scientific hypotheses are done and undone," said Paul Baker, Professor of Earth and Ocean Sciences at Duke University and a member of National Geographic Society's Committee for Research and Exploration.
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U.S. Geological Survey via The Archaeology News Network

The British Palaeolithic: Human Societies at the Edge of the Pleistocene World



Book: The British Palaeolithic: Human Societies at the Edge of the Pleistocene World (Routledge Archaeology of Northern Europe)
Paul Pettitt (Author), Mark White (Author)
Paperback: 616 pages
Publisher: Routledge; 1 edition (March 10, 2012)

The British Palaeolithic provides the first academic synthesis of the entire British Palaeolithic, from the earliest occupation (currently understood to be around 980,000 years ago) to the end of the Ice Age. Landscape and ecology form the canvas for an explicitly interpretative approach aimed at understanding the how different hominin societies addressed the issues of life at the edge of the Pleistocene world.  

Commencing with a consideration of the earliest hominin settlement of Europe, the book goes on to examine the behavioural, cultural and adaptive repertoires of the first human occupants of Britain from an ecological perspective. These themes flow throughout the book as it explores subsequent occupational pulses across more than half a million years of Pleistocene prehistory, which saw Homo heidelbergensis, the Neanderthals and ultimately Homo sapiens walk these shores...

An antler sickle form the Neolithic site of Costamar at Cabanes (Castellón) on the Mediterranean Spanish coast

Archaeological excavations at the settlement of Costamar (Figure 1) between 2006 and 2008 by the Fundació Marina d'Or uncovered an area of 57 905m² containing 683 archaeological features belonging to Neolithic, Bronze Age, Iberian, Roman, Islamic, late medieval, modern and contemporary times.

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A red deer antler sickle was found in Structure GE 398-651 (Figure 4), on the base of a circular pit with diameters of 1.08m and 0.79m at its opening and base respectively, and a depth of 0.31m. The sickle was found together with five undecorated base sherds of a recipient with red ochre remains on its outer surface (Figure 5). The vessel surface treatment is reminiscent of the combing technique seen at other sites in eastern Iberia in the transition period from the sixth to fifth millennium cal BC.

Figure 6. The antler sickle, with detail of haft.
... [Read more]
Antiquity Vol 86 No 332 June 2012. Project Gallery.

Hallada en Costamar una hoz sobre un asta de ciervo del neolítico
16-05-201/EFE. Los arqueólogos que trabajan en el yacimiento de Costamar, en Cabanes, han hallado el mango de una hoz fabricada con asta de ciervo durante el periodo neolítico.

Según ha informado la Fundación Marina d'Or en un comunicado, el hallazgo se ha producido en las excavaciones que realiza esa fundación y la Universidad Politécnica de Valencia en la zona bajo la dirección del arqueólogo Enric Flors.

La pieza ha sido analizada por responsables de la Institución Milá y Fontanals de la Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC-IMF).

La herramienta tiene una longitud de 37 centímetros y en la parte distal conserva uno de los extremos apuntados del asta que habría servido para recoger las espigas.

Este tipo de hoces, de las que hasta el momento solo se conocían las recuperadas en el yacimiento de La Draga, en Banyoles (Girona) que estaban realizadas sobre madera, se caracterizan por presentar una ranura en la cara superior con el fin de introducir una lámina de sílex insertada en diagonal, según ese comunicado.

La colaboración entre la fundación y la Universidad Politécnica de Valencia ha permitido la restauración y la conservación de centenares de piezas y mediante el convenio con la Universidad de Valencia se han realizado los análisis sobre los restos recuperados.

Hasta la fecha, se han excavado más de 100.000 metros cuadrados en los que se han hallado restos que datan desde el Neolítico Antiguo hasta la actualidad.

Además, según la Fundación Marina d'Or, se han recuperado más de 130.000 fragmentos cerámicos de diferentes épocas de los que se han analizado ya cerca de 50.000. Abc.es

Dartmoor Bronze Age burial remains X-rayed in Salisbury

Early Bronze Age remains from a burial site in Dartmoor National Park will be X-rayed at Salisbury District Hospital.

The items were found in a burial cist, a stone chest containing the ashes and belongings of a dead person.

Senior conservator, Helen Williams, said: "We have a real opportunity to research these finds and potentially discover more about the individual buried there."

The items, which include a woven bag, will be scanned at the spinal unit.

'Unusual and fascinating'

The burial cist was excavated from Whitehorse Hill in August 2011.

Archaeologists found cremated human bone, burnt textile, and a delicate woven bag inside.

The bag contained shale disc beads, amber spherical beads and a circular textile band.

Senior archaeologist for Dartmoor National Park Authority and Whitehorse Hill project manager, Jane Marchand, said: "This is a most unusual and fascinating glimpse into what an early Bronze Age grave goods assemblage on Dartmoor might have looked like as it was buried, including the personal possessions of people living on the Moor around 4,000 years ago."

Once the X-ray work is complete, further analysis will be made of the peat surrounding the cist.

Archaeologists believe this will give an insight into evidence of the vegetation and climate at the time of the burial.

Wiltshire Conservation Service will also be on hand to consult with the archaeology team on the x-ray results... BBC News

Related post

Where's the Beef? Early Humans Took It

PALISADES, NEW YORK. When human ancestors began scavenging for meat regularly on the open plains of Africa about 2.5 million years ago, they apparently took more than their fair share of flesh. Within a million years, most of the large carnivores in the region—from saber-toothed cats to bear-size otters—had gone extinct, leaving just a few "hypercarnivores" alive, according to study presented here last week at a workshop on climate change and human evolution.

Humans have driven thousands of species extinct over the millennia, ranging from moas—giant, flightless birds that lived in New Zealand—to most lemurs in Madagascar. But just when we began to have such a major impact is less clear. Researchers have long known that many African carnivores died out by 1.5 million years ago, and they blamed our ancestor, Homo erectus, for overhunting with its new stone tools. But few scientists thought there were enough hominins—ancestors of humans but not other apes—before that to threaten the fierce assortment of carnivores that roamed Africa, or that the crude stone tools that our ancestors began to wield 2.6 million years ago could be used for hunting. Besides, it was probably much more dangerous for the puny hominins alive then, such as Australopithecus afarensis, whose brain and body were only a bit bigger than a chimp's, to grab carcasses than it was for supersized carnivores such as giant hyenas, cats, and otters to devour hominins. "One of my favorite images is of an Au. afarensis being dragged down by a giant otter," says vertebrate paleontologist Lars Werdelin at the Swedish Museum of Natural History in Stockholm.
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Sciencemag.org

Big Think Interview With Donald Johanson

Vídeo YouTube (el 23/04/2012 por bigthink) añadido a Paleo Vídeos > Prehistoria Universal > L.R.2.3



A conversation with the paleoanthropologist and founding director of the Institute of Human Origins.