article_snippet: This is the equivalent amount of rock as that used to build the Great Pyramid of Giza in Egypt.
article_snippet: The researchers, whose work is published in the journal Public Library of Science
article_snippet: One conducted a survey of the site in the Sahara in 2011 by randomly examining plots along the plateau of the Massak Settafet enscarpment.
article_snippet: The researchers, whose work is published in the journal Public Library of Science sifted through the sandstone rocks in each plot searching for those that showed signs that The researchers, whose work is published in the journal Public Library of Science had been worked by humans.
article_snippet: This is created by the angular blow from a human as The researchers attempted to knock flakes off larger pieces of rock.
article_snippet: The rocks above appear to have been broken off a larger boulder or had chunks bashed off The rocks above by humans .
article_snippet: The research team from the University of Cambridge studied the rocks in metre square plots on the groun .