An assembly of huge stone slabs found in Egypt's Sahara Desert that date from about 6,500 years to 6,000 years ago has been confirmed by scientists to be the oldest known astronomical alignment of megaliths in the world.
     Known as Nabta, the site consists of a stone circle, a series of flat, tomb-like stone structures and five lines of standing and toppled megaliths. Located west of the Nile River in southern Egypt, Nabta predates Stonehenge and similar prehistoric sites around the world by about 1,000 years, said University of Colorado at Boulder astronomy Professor J. McKim Malville.
     A lot of effort went into the construction of a purely symbolic and ceremonial site. The stone slabs, some of which are nine feet high, were dragged to the site from a mile or more distant. The ruins lie on the shoreline of an ancient lake that began filling with water about 11,000 years ago when the African summer monsoon shifted north.
     Five megalithic alignments at Nabta radiate outward from a central collection of megalithic structures. Beneath one structure was a sculptured rock resembling a cow standing upright. No human remains have yet been found at Nabta. The 12-foot-in-diameter stone circle contains four sets of upright slabs. Two sets were aligned in a north-south direction while the second pair of slabs provides a line of sight toward the summer solstice horizon. Because of Nabta's proximity to the Tropic of Cancer, the noon sun is at its zenith about three weeks before and three weeks after the summer solstice, preventing upright objects from casting shadows. These vertical sighting stones in the circle corresp ond to the zenith sun during the summer solstice said Malville, an archeoastronomer. For many cultures in the tropics, the zenith sun has been a major event for millennia
     An east-west alignment also is present between one megalithic structure and two stone megaliths about a mile distant. There also are two other geometric lines involving about a dozen additional stone monuments that lead both northeast and southeast from the same megalith. We still don't understand the significance of these lines Malville said. During summer and fall, the individual stone monoliths would have been partially submerged in the lake and may have been ritual markers for the onset of the rainy season.Although some believe the high culture of subsequent Egyptian dynasties was borrowed from Mesopotamia and Syria, Malville and others believe the complex and symbolic Nabta culture may have stimulated the growth of the society that eventually constructed the first pyramids along the Nile about 4,500 years ago.
     The Nabta culture may have been a trigger for the development of social complexity in Egypt that later led to the Pharaonic dynasty he said. The Nabta project was funded primarily by the National Science.

Source: University of Colorado at Boulder Office of Public Relations