Dating petroglyphs - Sex Chat
Visiting times can range from half an hour for a quick walk along one of the paths or a full day if hiking all trails and exploring the volcanoes.
A central problem in archaeological research has been the Chronometrie dating of petroglyphs (rock engravings).Recent improvements in the understanding of the chemistry of rock varnish (or patina) that develops on rock surfaces in arid regions has resulted in the development of a calibrated dating technique, cation-ratio (CR) dating.This is based on calibrating chemical changes in minor and major trace elements in the varnish over time.PIXE is used to determine the bulk chemical constituents of small samples of varnish mechanically removed from within petroglyphs.The carvings have a huge variety of designs, some very complex, including animals, hunting scenes, people, masks, geometric patterns and abstract shapes, and in many places occur in dense groups with dozens on a single boulder.There are three designated sites for visitors, at Rinconada Canyon, Boca Negra Canyon and Piedras Marcadas Canyon (see map), part of Petroglyph National Monument, which was created relatively recently (1990) and includes 11 square miles of the mesa together with five fissure volcanoes, reached by a less-traveled route to the west.
The main part of the monument, in the east, adjoins the Albuquerque suburbs so a visit here is a long way removed from a wilderness experience but the land on the plateau is suitably arid and desert-like, sprinkled with cacti and home to rattlesnakes, lizards and other elusive creatures.
Despite the proximity to the city, the petroglyphs are largely free of modern graffiti, and although some are faded and indistinct, many are crisp and well defined.
Recent applications in western North America have yielded petroglyph dates of great importance in understanding the origins of art and the antiquity of human settlement in the western hemisphere.
In particular the CR dates on petroglyphs suggest that humans moved into the New World about 10 K yrs earlier than previously believed, and that the making of petroglyphs was one of the most ancient and long-lived cultural traditions in aboriginal North America.
Beyond the Rio Grande, Albuquerque is bordered on the west side by a low, barren, volcanic plateau (West Mesa) - 200 feet high and extending for over 15 miles, the only feature rising above the flat grasslands are the cones of several long-extinct volcanoes, but even these are small and unremarkable.
More interesting is the eastern edge, a steep slope of broken lava blocks, since here are found approximately 24,000 petroglyphs, most dating from the Ancestral Pueblo period of 1300 to 1600 AD, made by chipping away the dark, weathered surface of the lava to reveal the light-colored rock underneath.