Ancient people probably assembled the massive sandstone horseshoe at Stonehenge more than 4,600 years ago, while the smaller bluestones were imported from Wales later, a new study suggests.
     Past researchers believed the bluestone oval and circle were erected earlier than the massive sandstone horseshoe. When study co-author Timothy Darvill, an archaeologist at Bournemouth University in England, and his colleagues began excavations in 2008, they found the previous chronology didn't add up. The team estimated the age of new artefacts from the site. Combining the new information with dating from past excavations, the team created a new timeline for Stonehenge's construction.
     The new analysis suggests around 2600 BCE the Neolithic people built the giant sandstone horseshoe, drawing the stone from nearby quarries. Only later did other builders arrange the much smaller bluestones. Those bluestones were then rearranged at various positions throughout the site over the next millennium, Darvill said.
     The builders of the larger sandstone structures were pig farmers found only in the British Isles. In contrast, the bluestone builders would have been the 'Beaker' people - sheep and cow herders who lived throughout Europe, known for the distinctive, bell-shape pottery.

Edited from LiveScience (30 November 2012)